Mercurial > cpython-lru_cache-weakref

annotate Doc/lib/libstdtypes.tex @ 32527:0da660e05e69 legacy-trunk

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
"#if WITH_THREAD" is incorrect; must be #ifdef instead; WITH_THREAD isn't always set to an integer value when it's defined.
author Tim Peters <tim.peters@gmail.com>
date Wed, 07 Jul 2004 20:42:07 +0000
parents 6b1ea5c07ff7
children 46e0431c9701
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
1 \section{Built-in Types \label{types}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
2
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
3 The following sections describe the standard types that are built into
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
4 the interpreter. Historically, Python's built-in types have differed
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
5 from user-defined types because it was not possible to use the built-in
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
6 types as the basis for object-oriented inheritance. With the 2.2
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
7 release this situation has started to change, although the intended
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
8 unification of user-defined and built-in types is as yet far from
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
9 complete.
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
10
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
11 The principal built-in types are numerics, sequences, mappings, files
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
12 classes, instances and exceptions.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
13 \indexii{built-in}{types}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
14
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
15 Some operations are supported by several object types; in particular,
31298
ad3faf52e19e Correct misrepresentation of print (it uses str(), not `...` for
Guido van Rossum <guido@python.org>
parents: 31286
diff changeset
16 practically all objects can be compared, tested for truth value,
ad3faf52e19e Correct misrepresentation of print (it uses str(), not `...` for
Guido van Rossum <guido@python.org>
parents: 31286
diff changeset
17 and converted to a string (with the \code{`\textrm{\ldots}`} notation,
ad3faf52e19e Correct misrepresentation of print (it uses str(), not `...` for
Guido van Rossum <guido@python.org>
parents: 31286
diff changeset
18 the equivalent \function{repr()} function, or the slightly different
ad3faf52e19e Correct misrepresentation of print (it uses str(), not `...` for
Guido van Rossum <guido@python.org>
parents: 31286
diff changeset
19 \function{str()} function). The latter
ad3faf52e19e Correct misrepresentation of print (it uses str(), not `...` for
Guido van Rossum <guido@python.org>
parents: 31286
diff changeset
20 function is implicitly used when an object is written by the
9558
fa867d8ee7eb Remove some remaining {\rm ...} constructs.
Fred Drake <fdrake@acm.org>
parents: 9523
diff changeset
21 \keyword{print}\stindex{print} statement.
28909
06abfc9c68e7 At the site of an indexed reference to print, point to the relevant
Fred Drake <fdrake@acm.org>
parents: 28606
diff changeset
22 (Information on \ulink{\keyword{print} statement}{../ref/print.html}
06abfc9c68e7 At the site of an indexed reference to print, point to the relevant
Fred Drake <fdrake@acm.org>
parents: 28606
diff changeset
23 and other language statements can be found in the
06abfc9c68e7 At the site of an indexed reference to print, point to the relevant
Fred Drake <fdrake@acm.org>
parents: 28606
diff changeset
24 \citetitle[../ref/ref.html]{Python Reference Manual} and the
06abfc9c68e7 At the site of an indexed reference to print, point to the relevant
Fred Drake <fdrake@acm.org>
parents: 28606
diff changeset
25 \citetitle[../tut/tut.html]{Python Tutorial}.)
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
26
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
27
28909
06abfc9c68e7 At the site of an indexed reference to print, point to the relevant
Fred Drake <fdrake@acm.org>
parents: 28606
diff changeset
28 \subsection{Truth Value Testing\label{truth}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
29
9558
fa867d8ee7eb Remove some remaining {\rm ...} constructs.
Fred Drake <fdrake@acm.org>
parents: 9523
diff changeset
30 Any object can be tested for truth value, for use in an \keyword{if} or
fa867d8ee7eb Remove some remaining {\rm ...} constructs.
Fred Drake <fdrake@acm.org>
parents: 9523
diff changeset
31 \keyword{while} condition or as operand of the Boolean operations below.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
32 The following values are considered false:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
33 \stindex{if}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
34 \stindex{while}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
35 \indexii{truth}{value}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
36 \indexii{Boolean}{operations}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
37 \index{false}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
38
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
39 \begin{itemize}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
40
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
41 \item \code{None}
24631
110c6edaf62f Clarify that the bool instances are acceptable return values from
Fred Drake <fdrake@acm.org>
parents: 24599
diff changeset
42 \withsubitem{(Built-in object)}{\ttindex{None}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
43
22785
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
44 \item \code{False}
24631
110c6edaf62f Clarify that the bool instances are acceptable return values from
Fred Drake <fdrake@acm.org>
parents: 24599
diff changeset
45 \withsubitem{(Built-in object)}{\ttindex{False}}
22785
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
46
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
47 \item zero of any numeric type, for example, \code{0}, \code{0L},
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
48 \code{0.0}, \code{0j}.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
49
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
50 \item any empty sequence, for example, \code{''}, \code{()}, \code{[]}.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
51
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
52 \item any empty mapping, for example, \code{\{\}}.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
53
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
54 \item instances of user-defined classes, if the class defines a
24631
110c6edaf62f Clarify that the bool instances are acceptable return values from
Fred Drake <fdrake@acm.org>
parents: 24599
diff changeset
55 \method{__nonzero__()} or \method{__len__()} method, when that
110c6edaf62f Clarify that the bool instances are acceptable return values from
Fred Drake <fdrake@acm.org>
parents: 24599
diff changeset
56 method returns the integer zero or \class{bool} value
110c6edaf62f Clarify that the bool instances are acceptable return values from
Fred Drake <fdrake@acm.org>
parents: 24599
diff changeset
57 \code{False}.\footnote{Additional
24227
8a67f28a42a5 Clarify the return value of __nonzero__(): It *must* be an integer.
Fred Drake <fdrake@acm.org>
parents: 23860
diff changeset
58 information on these special methods may be found in the
8a67f28a42a5 Clarify the return value of __nonzero__(): It *must* be an integer.
Fred Drake <fdrake@acm.org>
parents: 23860
diff changeset
59 \citetitle[../ref/ref.html]{Python Reference Manual}.}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
60
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
61 \end{itemize}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
62
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
63 All other values are considered true --- so objects of many types are
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
64 always true.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
65 \index{true}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
66
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
67 Operations and built-in functions that have a Boolean result always
22785
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
68 return \code{0} or \code{False} for false and \code{1} or \code{True}
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
69 for true, unless otherwise stated. (Important exception: the Boolean
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
70 operations \samp{or}\opindex{or} and \samp{and}\opindex{and} always
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
71 return one of their operands.)
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
72 \index{False}
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
73 \index{True}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
74
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
75 \subsection{Boolean Operations \label{boolean}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
76
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
77 These are the Boolean operations, ordered by ascending priority:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
78 \indexii{Boolean}{operations}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
79
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
80 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
81 \lineiii{\var{x} or \var{y}}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
82 {if \var{x} is false, then \var{y}, else \var{x}}{(1)}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
83 \lineiii{\var{x} and \var{y}}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
84 {if \var{x} is false, then \var{x}, else \var{y}}{(1)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
85 \hline
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
86 \lineiii{not \var{x}}
22785
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
87 {if \var{x} is false, then \code{True}, else \code{False}}{(2)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
88 \end{tableiii}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
89 \opindex{and}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
90 \opindex{or}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
91 \opindex{not}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
92
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
93 \noindent
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
94 Notes:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
95
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
96 \begin{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
97
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
98 \item[(1)]
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
99 These only evaluate their second argument if needed for their outcome.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
100
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
101 \item[(2)]
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
102 \samp{not} has a lower priority than non-Boolean operators, so
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
103 \code{not \var{a} == \var{b}} is interpreted as \code{not (\var{a} ==
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
104 \var{b})}, and \code{\var{a} == not \var{b}} is a syntax error.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
105
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
106 \end{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
107
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
108
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
109 \subsection{Comparisons \label{comparisons}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
110
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
111 Comparison operations are supported by all objects. They all have the
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
112 same priority (which is higher than that of the Boolean operations).
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
113 Comparisons can be chained arbitrarily; for example, \code{\var{x} <
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
114 \var{y} <= \var{z}} is equivalent to \code{\var{x} < \var{y} and
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
115 \var{y} <= \var{z}}, except that \var{y} is evaluated only once (but
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
116 in both cases \var{z} is not evaluated at all when \code{\var{x} <
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
117 \var{y}} is found to be false).
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
118 \indexii{chaining}{comparisons}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
119
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
120 This table summarizes the comparison operations:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
121
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
122 \begin{tableiii}{c|l|c}{code}{Operation}{Meaning}{Notes}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
123 \lineiii{<}{strictly less than}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
124 \lineiii{<=}{less than or equal}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
125 \lineiii{>}{strictly greater than}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
126 \lineiii{>=}{greater than or equal}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
127 \lineiii{==}{equal}{}
14044
a905c5aa0691 As pointed out by Denis S. Otkidach <den@analyt.chem.msu.ru>, xrange()
Fred Drake <fdrake@acm.org>
parents: 13967
diff changeset
128 \lineiii{!=}{not equal}{(1)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
129 \lineiii{<>}{not equal}{(1)}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
130 \lineiii{is}{object identity}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
131 \lineiii{is not}{negated object identity}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
132 \end{tableiii}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
133 \indexii{operator}{comparison}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
134 \opindex{==} % XXX *All* others have funny characters < ! >
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
135 \opindex{is}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
136 \opindex{is not}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
137
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
138 \noindent
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
139 Notes:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
140
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
141 \begin{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
142
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
143 \item[(1)]
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
144 \code{<>} and \code{!=} are alternate spellings for the same operator.
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
145 \code{!=} is the preferred spelling; \code{<>} is obsolescent.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
146
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
147 \end{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
148
29343
e4f70e602598 Patch #744238: Explain that different string types also may compare equal.
Martin v. Löwis <martin@v.loewis.de>
parents: 29067
diff changeset
149 Objects of different types, except different numeric types and different string types, never
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
150 compare equal; such objects are ordered consistently but arbitrarily
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
151 (so that sorting a heterogeneous array yields a consistent result).
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
152 Furthermore, some types (for example, file objects) support only a
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
153 degenerate notion of comparison where any two objects of that type are
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
154 unequal. Again, such objects are ordered arbitrarily but
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
155 consistently. The \code{<}, \code{<=}, \code{>} and \code{>=}
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
156 operators will raise a \exception{TypeError} exception when any operand
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
157 is a complex number.
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
158 \indexii{object}{numeric}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
159 \indexii{objects}{comparing}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
160
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
161 Instances of a class normally compare as non-equal unless the class
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
162 \withsubitem{(instance method)}{\ttindex{__cmp__()}}
14485
ac0246586d52 Improve a couple of references to the language reference, making them
Fred Drake <fdrake@acm.org>
parents: 14044
diff changeset
163 defines the \method{__cmp__()} method. Refer to the
ac0246586d52 Improve a couple of references to the language reference, making them
Fred Drake <fdrake@acm.org>
parents: 14044
diff changeset
164 \citetitle[../ref/customization.html]{Python Reference Manual} for
ac0246586d52 Improve a couple of references to the language reference, making them
Fred Drake <fdrake@acm.org>
parents: 14044
diff changeset
165 information on the use of this method to effect object comparisons.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
166
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
167 \strong{Implementation note:} Objects of different types except
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
168 numbers are ordered by their type names; objects of the same types
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
169 that don't support proper comparison are ordered by their address.
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
170
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
171 Two more operations with the same syntactic priority,
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
172 \samp{in}\opindex{in} and \samp{not in}\opindex{not in}, are supported
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
173 only by sequence types (below).
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
174
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
175
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
176 \subsection{Numeric Types \label{typesnumeric}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
177
22785
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
178 There are four distinct numeric types: \dfn{plain integers},
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
179 \dfn{long integers},
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
180 \dfn{floating point numbers}, and \dfn{complex numbers}.
22785
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
181 In addition, Booleans are a subtype of plain integers.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
182 Plain integers (also just called \dfn{integers})
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
183 are implemented using \ctype{long} in C, which gives them at least 32
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
184 bits of precision. Long integers have unlimited precision. Floating
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
185 point numbers are implemented using \ctype{double} in C. All bets on
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
186 their precision are off unless you happen to know the machine you are
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
187 working with.
15005
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
188 \obindex{numeric}
22785
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
189 \obindex{Boolean}
15005
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
190 \obindex{integer}
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
191 \obindex{long integer}
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
192 \obindex{floating point}
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
193 \obindex{complex number}
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
194 \indexii{C}{language}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
195
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
196 Complex numbers have a real and imaginary part, which are each
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
197 implemented using \ctype{double} in C. To extract these parts from
22241
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
198 a complex number \var{z}, use \code{\var{z}.real} and \code{\var{z}.imag}.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
199
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
200 Numbers are created by numeric literals or as the result of built-in
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
201 functions and operators. Unadorned integer literals (including hex
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
202 and octal numbers) yield plain integers unless the value they denote
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
203 is too large to be represented as a plain integer, in which case
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
204 they yield a long integer. Integer literals with an
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
205 \character{L} or \character{l} suffix yield long integers
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
206 (\character{L} is preferred because \samp{1l} looks too much like
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
207 eleven!). Numeric literals containing a decimal point or an exponent
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
208 sign yield floating point numbers. Appending \character{j} or
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
209 \character{J} to a numeric literal yields a complex number with a
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
210 zero real part. A complex numeric literal is the sum of a real and
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
211 an imaginary part.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
212 \indexii{numeric}{literals}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
213 \indexii{integer}{literals}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
214 \indexiii{long}{integer}{literals}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
215 \indexii{floating point}{literals}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
216 \indexii{complex number}{literals}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
217 \indexii{hexadecimal}{literals}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
218 \indexii{octal}{literals}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
219
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
220 Python fully supports mixed arithmetic: when a binary arithmetic
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
221 operator has operands of different numeric types, the operand with the
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
222 ``narrower'' type is widened to that of the other, where plain
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
223 integer is narrower than long integer is narrower than floating point is
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
224 narrower than complex.
10520
7ee1e3134147 Fixed latex2html weirdness with footnotes.
Fred Drake <fdrake@acm.org>
parents: 10241
diff changeset
225 Comparisons between numbers of mixed type use the same rule.\footnote{
7ee1e3134147 Fixed latex2html weirdness with footnotes.
Fred Drake <fdrake@acm.org>
parents: 10241
diff changeset
226 As a consequence, the list \code{[1, 2]} is considered equal
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
227 to \code{[1.0, 2.0]}, and similarly for tuples.
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
228 } The constructors \function{int()}, \function{long()}, \function{float()},
9558
fa867d8ee7eb Remove some remaining {\rm ...} constructs.
Fred Drake <fdrake@acm.org>
parents: 9523
diff changeset
229 and \function{complex()} can be used
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
230 to produce numbers of a specific type.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
231 \index{arithmetic}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
232 \bifuncindex{int}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
233 \bifuncindex{long}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
234 \bifuncindex{float}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
235 \bifuncindex{complex}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
236
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
237 All numeric types (except complex) support the following operations,
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
238 sorted by ascending priority (operations in the same box have the same
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
239 priority; all numeric operations have a higher priority than
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
240 comparison operations):
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
241
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
242 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
243 \lineiii{\var{x} + \var{y}}{sum of \var{x} and \var{y}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
244 \lineiii{\var{x} - \var{y}}{difference of \var{x} and \var{y}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
245 \hline
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
246 \lineiii{\var{x} * \var{y}}{product of \var{x} and \var{y}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
247 \lineiii{\var{x} / \var{y}}{quotient of \var{x} and \var{y}}{(1)}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
248 \lineiii{\var{x} \%{} \var{y}}{remainder of \code{\var{x} / \var{y}}}{(4)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
249 \hline
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
250 \lineiii{-\var{x}}{\var{x} negated}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
251 \lineiii{+\var{x}}{\var{x} unchanged}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
252 \hline
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
253 \lineiii{abs(\var{x})}{absolute value or magnitude of \var{x}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
254 \lineiii{int(\var{x})}{\var{x} converted to integer}{(2)}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
255 \lineiii{long(\var{x})}{\var{x} converted to long integer}{(2)}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
256 \lineiii{float(\var{x})}{\var{x} converted to floating point}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
257 \lineiii{complex(\var{re},\var{im})}{a complex number with real part \var{re}, imaginary part \var{im}. \var{im} defaults to zero.}{}
10147
3ac7f0066375 Document <complex #>.conjugate().
Fred Drake <fdrake@acm.org>
parents: 9558
diff changeset
258 \lineiii{\var{c}.conjugate()}{conjugate of the complex number \var{c}}{}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
259 \lineiii{divmod(\var{x}, \var{y})}{the pair \code{(\var{x} / \var{y}, \var{x} \%{} \var{y})}}{(3)(4)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
260 \lineiii{pow(\var{x}, \var{y})}{\var{x} to the power \var{y}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
261 \lineiii{\var{x} ** \var{y}}{\var{x} to the power \var{y}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
262 \end{tableiii}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
263 \indexiii{operations on}{numeric}{types}
10147
3ac7f0066375 Document <complex #>.conjugate().
Fred Drake <fdrake@acm.org>
parents: 9558
diff changeset
264 \withsubitem{(complex number method)}{\ttindex{conjugate()}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
265
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
266 \noindent
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
267 Notes:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
268 \begin{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
269
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
270 \item[(1)]
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
271 For (plain or long) integer division, the result is an integer.
22241
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
272 The result is always rounded towards minus infinity: 1/2 is 0,
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
273 (-1)/2 is -1, 1/(-2) is -1, and (-1)/(-2) is 0. Note that the result
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
274 is a long integer if either operand is a long integer, regardless of
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
275 the numeric value.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
276 \indexii{integer}{division}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
277 \indexiii{long}{integer}{division}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
278
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
279 \item[(2)]
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
280 Conversion from floating point to (long or plain) integer may round or
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
281 truncate as in C; see functions \function{floor()} and
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
282 \function{ceil()} in the \refmodule{math}\refbimodindex{math} module
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
283 for well-defined conversions.
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
284 \withsubitem{(in module math)}{\ttindex{floor()}\ttindex{ceil()}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
285 \indexii{numeric}{conversions}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
286 \indexii{C}{language}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
287
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
288 \item[(3)]
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
289 See section \ref{built-in-funcs}, ``Built-in Functions,'' for a full
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
290 description.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
291
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
292 \item[(4)]
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
293 Complex floor division operator, modulo operator, and \function{divmod()}.
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
294
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
295 \deprecated{2.3}{Instead convert to float using \function{abs()}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
296 if appropriate.}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
297
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
298 \end{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
299 % XXXJH exceptions: overflow (when? what operations?) zerodivision
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
300
10241
f138ba72bf2d Update description of what modules "look like" when printed.
Fred Drake <fdrake@acm.org>
parents: 10156
diff changeset
301 \subsubsection{Bit-string Operations on Integer Types \label{bitstring-ops}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
302 \nodename{Bit-string Operations}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
303
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
304 Plain and long integer types support additional operations that make
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
305 sense only for bit-strings. Negative numbers are treated as their 2's
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
306 complement value (for long integers, this assumes a sufficiently large
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
307 number of bits that no overflow occurs during the operation).
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
308
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
309 The priorities of the binary bit-wise operations are all lower than
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
310 the numeric operations and higher than the comparisons; the unary
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
311 operation \samp{\~} has the same priority as the other unary numeric
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
312 operations (\samp{+} and \samp{-}).
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
313
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
314 This table lists the bit-string operations sorted in ascending
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
315 priority (operations in the same box have the same priority):
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
316
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
317 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
318 \lineiii{\var{x} | \var{y}}{bitwise \dfn{or} of \var{x} and \var{y}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
319 \lineiii{\var{x} \^{} \var{y}}{bitwise \dfn{exclusive or} of \var{x} and \var{y}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
320 \lineiii{\var{x} \&{} \var{y}}{bitwise \dfn{and} of \var{x} and \var{y}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
321 \lineiii{\var{x} << \var{n}}{\var{x} shifted left by \var{n} bits}{(1), (2)}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
322 \lineiii{\var{x} >> \var{n}}{\var{x} shifted right by \var{n} bits}{(1), (3)}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
323 \hline
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
324 \lineiii{\~\var{x}}{the bits of \var{x} inverted}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
325 \end{tableiii}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
326 \indexiii{operations on}{integer}{types}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
327 \indexii{bit-string}{operations}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
328 \indexii{shifting}{operations}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
329 \indexii{masking}{operations}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
330
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
331 \noindent
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
332 Notes:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
333 \begin{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
334 \item[(1)] Negative shift counts are illegal and cause a
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
335 \exception{ValueError} to be raised.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
336 \item[(2)] A left shift by \var{n} bits is equivalent to
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
337 multiplication by \code{pow(2, \var{n})} without overflow check.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
338 \item[(3)] A right shift by \var{n} bits is equivalent to
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
339 division by \code{pow(2, \var{n})} without overflow check.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
340 \end{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
341
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
342
17658
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
343 \subsection{Iterator Types \label{typeiter}}
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
344
17663
d76649bd38d0 The general iteration support is part of 2.2, not 2.1 -- fixed the version
Fred Drake <fdrake@acm.org>
parents: 17658
diff changeset
345 \versionadded{2.2}
17658
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
346 \index{iterator protocol}
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
347 \index{protocol!iterator}
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
348 \index{sequence!iteration}
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
349 \index{container!iteration over}
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
350
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
351 Python supports a concept of iteration over containers. This is
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
352 implemented using two distinct methods; these are used to allow
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
353 user-defined classes to support iteration. Sequences, described below
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
354 in more detail, always support the iteration methods.
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
355
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
356 One method needs to be defined for container objects to provide
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
357 iteration support:
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
358
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
359 \begin{methoddesc}[container]{__iter__}{}
18839
ab8aa4302109 Typo fix.
Greg Ward <gward@python.net>
parents: 18829
diff changeset
360 Return an iterator object. The object is required to support the
17658
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
361 iterator protocol described below. If a container supports
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
362 different types of iteration, additional methods can be provided to
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
363 specifically request iterators for those iteration types. (An
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
364 example of an object supporting multiple forms of iteration would be
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
365 a tree structure which supports both breadth-first and depth-first
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
366 traversal.) This method corresponds to the \member{tp_iter} slot of
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
367 the type structure for Python objects in the Python/C API.
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
368 \end{methoddesc}
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
369
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
370 The iterator objects themselves are required to support the following
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
371 two methods, which together form the \dfn{iterator protocol}:
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
372
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
373 \begin{methoddesc}[iterator]{__iter__}{}
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
374 Return the iterator object itself. This is required to allow both
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
375 containers and iterators to be used with the \keyword{for} and
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
376 \keyword{in} statements. This method corresponds to the
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
377 \member{tp_iter} slot of the type structure for Python objects in
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
378 the Python/C API.
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
379 \end{methoddesc}
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
380
17663
d76649bd38d0 The general iteration support is part of 2.2, not 2.1 -- fixed the version
Fred Drake <fdrake@acm.org>
parents: 17658
diff changeset
381 \begin{methoddesc}[iterator]{next}{}
17658
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
382 Return the next item from the container. If there are no further
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
383 items, raise the \exception{StopIteration} exception. This method
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
384 corresponds to the \member{tp_iternext} slot of the type structure
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
385 for Python objects in the Python/C API.
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
386 \end{methoddesc}
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
387
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
388 Python defines several iterator objects to support iteration over
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
389 general and specific sequence types, dictionaries, and other more
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
390 specialized forms. The specific types are not important beyond their
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
391 implementation of the iterator protocol.
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
392
24253
62f4b45b05fd Record the decision that StopIteration is a sink state (see recent
Guido van Rossum <guido@python.org>
parents: 24227
diff changeset
393 The intention of the protocol is that once an iterator's
62f4b45b05fd Record the decision that StopIteration is a sink state (see recent
Guido van Rossum <guido@python.org>
parents: 24227
diff changeset
394 \method{next()} method raises \exception{StopIteration}, it will
62f4b45b05fd Record the decision that StopIteration is a sink state (see recent
Guido van Rossum <guido@python.org>
parents: 24227
diff changeset
395 continue to do so on subsequent calls. Implementations that
62f4b45b05fd Record the decision that StopIteration is a sink state (see recent
Guido van Rossum <guido@python.org>
parents: 24227
diff changeset
396 do not obey this property are deemed broken. (This constraint
62f4b45b05fd Record the decision that StopIteration is a sink state (see recent
Guido van Rossum <guido@python.org>
parents: 24227
diff changeset
397 was added in Python 2.3; in Python 2.2, various iterators are
62f4b45b05fd Record the decision that StopIteration is a sink state (see recent
Guido van Rossum <guido@python.org>
parents: 24227
diff changeset
398 broken according to this rule.)
62f4b45b05fd Record the decision that StopIteration is a sink state (see recent
Guido van Rossum <guido@python.org>
parents: 24227
diff changeset
399
29590
8807e901c526 SF bug #696777: How to make a class iterable using a member generator.
Raymond Hettinger <python@rcn.com>
parents: 29516
diff changeset
400 Python's generators provide a convenient way to implement the
8807e901c526 SF bug #696777: How to make a class iterable using a member generator.
Raymond Hettinger <python@rcn.com>
parents: 29516
diff changeset
401 iterator protocol. If a container object's \method{__iter__()}
8807e901c526 SF bug #696777: How to make a class iterable using a member generator.
Raymond Hettinger <python@rcn.com>
parents: 29516
diff changeset
402 method is implemented as a generator, it will automatically
8807e901c526 SF bug #696777: How to make a class iterable using a member generator.
Raymond Hettinger <python@rcn.com>
parents: 29516
diff changeset
403 return an iterator object (technically, a generator object)
8807e901c526 SF bug #696777: How to make a class iterable using a member generator.
Raymond Hettinger <python@rcn.com>
parents: 29516
diff changeset
404 supplying the \method{__iter__()} and \method{next()} methods.
8807e901c526 SF bug #696777: How to make a class iterable using a member generator.
Raymond Hettinger <python@rcn.com>
parents: 29516
diff changeset
405
17658
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
406
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
407 \subsection{Sequence Types \label{typesseq}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
408
13967
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
409 There are six sequence types: strings, Unicode strings, lists,
14044
a905c5aa0691 As pointed out by Denis S. Otkidach <den@analyt.chem.msu.ru>, xrange()
Fred Drake <fdrake@acm.org>
parents: 13967
diff changeset
410 tuples, buffers, and xrange objects.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
411
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
412 String literals are written in single or double quotes:
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
413 \code{'xyzzy'}, \code{"frobozz"}. See chapter 2 of the
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
414 \citetitle[../ref/strings.html]{Python Reference Manual} for more about
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
415 string literals. Unicode strings are much like strings, but are
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
416 specified in the syntax using a preceeding \character{u} character:
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
417 \code{u'abc'}, \code{u"def"}. Lists are constructed with square brackets,
11463
17e12305973e Use \citetitle and \programopt as appropriate.
Fred Drake <fdrake@acm.org>
parents: 11183
diff changeset
418 separating items with commas: \code{[a, b, c]}. Tuples are
17e12305973e Use \citetitle and \programopt as appropriate.
Fred Drake <fdrake@acm.org>
parents: 11183
diff changeset
419 constructed by the comma operator (not within square brackets), with
17e12305973e Use \citetitle and \programopt as appropriate.
Fred Drake <fdrake@acm.org>
parents: 11183
diff changeset
420 or without enclosing parentheses, but an empty tuple must have the
30375
4aa84a8b1fe4 Fix spacing markup and other sundries.
Raymond Hettinger <python@rcn.com>
parents: 30250
diff changeset
421 enclosing parentheses, such as \code{a, b, c} or \code{()}. A single
4aa84a8b1fe4 Fix spacing markup and other sundries.
Raymond Hettinger <python@rcn.com>
parents: 30250
diff changeset
422 item tuple must have a trailing comma, such as \code{(d,)}.
15005
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
423 \obindex{sequence}
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
424 \obindex{string}
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
425 \obindex{Unicode}
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
426 \obindex{tuple}
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
427 \obindex{list}
18395
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
428
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
429 Buffer objects are not directly supported by Python syntax, but can be
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
430 created by calling the builtin function
25393
f559e97a41be Remove spurious period.
Fred Drake <fdrake@acm.org>
parents: 24902
diff changeset
431 \function{buffer()}.\bifuncindex{buffer} They don't support
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
432 concatenation or repetition.
18395
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
433 \obindex{buffer}
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
434
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
435 Xrange objects are similar to buffers in that there is no specific
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
436 syntax to create them, but they are created using the \function{xrange()}
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
437 function.\bifuncindex{xrange} They don't support slicing,
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
438 concatenation or repetition, and using \code{in}, \code{not in},
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
439 \function{min()} or \function{max()} on them is inefficient.
15005
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
440 \obindex{xrange}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
441
18395
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
442 Most sequence types support the following operations. The \samp{in} and
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
443 \samp{not in} operations have the same priorities as the comparison
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
444 operations. The \samp{+} and \samp{*} operations have the same
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
445 priority as the corresponding numeric operations.\footnote{They must
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
446 have since the parser can't tell the type of the operands.}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
447
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
448 This table lists the sequence operations sorted in ascending priority
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
449 (operations in the same box have the same priority). In the table,
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
450 \var{s} and \var{t} are sequences of the same type; \var{n}, \var{i}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
451 and \var{j} are integers:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
452
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
453 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
24598
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
454 \lineiii{\var{x} in \var{s}}{\code{1} if an item of \var{s} is equal to \var{x}, else \code{0}}{(1)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
455 \lineiii{\var{x} not in \var{s}}{\code{0} if an item of \var{s} is
24598
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
456 equal to \var{x}, else \code{1}}{(1)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
457 \hline
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
458 \lineiii{\var{s} + \var{t}}{the concatenation of \var{s} and \var{t}}{}
24598
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
459 \lineiii{\var{s} * \var{n}\textrm{,} \var{n} * \var{s}}{\var{n} shallow copies of \var{s} concatenated}{(2)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
460 \hline
24598
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
461 \lineiii{\var{s}[\var{i}]}{\var{i}'th item of \var{s}, origin 0}{(3)}
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
462 \lineiii{\var{s}[\var{i}:\var{j}]}{slice of \var{s} from \var{i} to \var{j}}{(3), (4)}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
463 \lineiii{\var{s}[\var{i}:\var{j}:\var{k}]}{slice of \var{s} from \var{i} to \var{j} with step \var{k}}{(3), (5)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
464 \hline
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
465 \lineiii{len(\var{s})}{length of \var{s}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
466 \lineiii{min(\var{s})}{smallest item of \var{s}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
467 \lineiii{max(\var{s})}{largest item of \var{s}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
468 \end{tableiii}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
469 \indexiii{operations on}{sequence}{types}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
470 \bifuncindex{len}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
471 \bifuncindex{min}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
472 \bifuncindex{max}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
473 \indexii{concatenation}{operation}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
474 \indexii{repetition}{operation}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
475 \indexii{subscript}{operation}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
476 \indexii{slice}{operation}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
477 \indexii{extended slice}{operation}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
478 \opindex{in}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
479 \opindex{not in}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
480
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
481 \noindent
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
482 Notes:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
483
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
484 \begin{description}
24598
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
485 \item[(1)] When \var{s} is a string or Unicode string object the
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
486 \code{in} and \code{not in} operations act like a substring test. In
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
487 Python versions before 2.3, \var{x} had to be a string of length 1.
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
488 In Python 2.3 and beyond, \var{x} may be a string of any length.
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
489
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
490 \item[(2)] Values of \var{n} less than \code{0} are treated as
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
491 \code{0} (which yields an empty sequence of the same type as
19529
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
492 \var{s}). Note also that the copies are shallow; nested structures
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
493 are not copied. This often haunts new Python programmers; consider:
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
494
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
495 \begin{verbatim}
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
496 >>> lists = [[]] * 3
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
497 >>> lists
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
498 [[], [], []]
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
499 >>> lists[0].append(3)
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
500 >>> lists
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
501 [[3], [3], [3]]
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
502 \end{verbatim}
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
503
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
504 What has happened is that \code{lists} is a list containing three
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
505 copies of the list \code{[[]]} (a one-element list containing an
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
506 empty list), but the contained list is shared by each copy. You can
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
507 create a list of different lists this way:
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
508
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
509 \begin{verbatim}
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
510 >>> lists = [[] for i in range(3)]
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
511 >>> lists[0].append(3)
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
512 >>> lists[1].append(5)
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
513 >>> lists[2].append(7)
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
514 >>> lists
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
515 [[3], [5], [7]]
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
516 \end{verbatim}
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
517
24598
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
518 \item[(3)] If \var{i} or \var{j} is negative, the index is relative to
18416
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make
Fred Drake <fdrake@acm.org>
parents: 18395
diff changeset
519 the end of the string: \code{len(\var{s}) + \var{i}} or
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
520 \code{len(\var{s}) + \var{j}} is substituted. But note that \code{-0} is
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
521 still \code{0}.
22241
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
522
24598
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
523 \item[(4)] The slice of \var{s} from \var{i} to \var{j} is defined as
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
524 the sequence of items with index \var{k} such that \code{\var{i} <=
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
525 \var{k} < \var{j}}. If \var{i} or \var{j} is greater than
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
526 \code{len(\var{s})}, use \code{len(\var{s})}. If \var{i} is omitted,
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
527 use \code{0}. If \var{j} is omitted, use \code{len(\var{s})}. If
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
528 \var{i} is greater than or equal to \var{j}, the slice is empty.
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
529
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
530 \item[(5)] The slice of \var{s} from \var{i} to \var{j} with step
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
531 \var{k} is defined as the sequence of items with index
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
532 \code{\var{x} = \var{i} + \var{n}*\var{k}} such that \code{0}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
533 \code{<=} \var{n} \code{<} \code{abs(i-j)}. If \var{i} or \var{j}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
534 is greater than \code{len(\var{s})}, use \code{len(\var{s})}. If
30250
830c0cd8fdb2 SF patch #797180: Bug 792656: slicing explained
Raymond Hettinger <python@rcn.com>
parents: 30095
diff changeset
535 \var{i} or \var{j} are omitted then they become ``end'' values
830c0cd8fdb2 SF patch #797180: Bug 792656: slicing explained
Raymond Hettinger <python@rcn.com>
parents: 30095
diff changeset
536 (which end depends on the sign of \var{k}). Note, \var{k} cannot
830c0cd8fdb2 SF patch #797180: Bug 792656: slicing explained
Raymond Hettinger <python@rcn.com>
parents: 30095
diff changeset
537 be zero.
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
538
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
539 \end{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
540
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
541
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
542 \subsubsection{String Methods \label{string-methods}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
543
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
544 These are the string methods which both 8-bit strings and Unicode
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
545 objects support:
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
546
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
547 \begin{methoddesc}[string]{capitalize}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
548 Return a copy of the string with only its first character capitalized.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
549
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
550 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
551 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
552
31021
21a10c3600b5 Add optional fillchar argument to ljust(), rjust(), and center() string methods.
Raymond Hettinger <python@rcn.com>
parents: 31008
diff changeset
553 \begin{methoddesc}[string]{center}{width\optional{, fillchar}}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
554 Return centered in a string of length \var{width}. Padding is done
31021
21a10c3600b5 Add optional fillchar argument to ljust(), rjust(), and center() string methods.
Raymond Hettinger <python@rcn.com>
parents: 31008
diff changeset
555 using the specified \var{fillchar} (default is a space).
31022
845f19b145a8 Add version changed doc for addition of fillchar to ljust/rjust/center
Neal Norwitz <nnorwitz@gmail.com>
parents: 31021
diff changeset
556 \versionchanged[Support for the \var{fillchar} argument]{2.4}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
557 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
558
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
559 \begin{methoddesc}[string]{count}{sub\optional{, start\optional{, end}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
560 Return the number of occurrences of substring \var{sub} in string
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
561 S\code{[\var{start}:\var{end}]}. Optional arguments \var{start} and
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
562 \var{end} are interpreted as in slice notation.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
563 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
564
21332
fbbd8a4ca7a6 Added documentation for str.decode().
Fred Drake <fdrake@acm.org>
parents: 21177
diff changeset
565 \begin{methoddesc}[string]{decode}{\optional{encoding\optional{, errors}}}
fbbd8a4ca7a6 Added documentation for str.decode().
Fred Drake <fdrake@acm.org>
parents: 21177
diff changeset
566 Decodes the string using the codec registered for \var{encoding}.
fbbd8a4ca7a6 Added documentation for str.decode().
Fred Drake <fdrake@acm.org>
parents: 21177
diff changeset
567 \var{encoding} defaults to the default string encoding. \var{errors}
fbbd8a4ca7a6 Added documentation for str.decode().
Fred Drake <fdrake@acm.org>
parents: 21177
diff changeset
568 may be given to set a different error handling scheme. The default is
fbbd8a4ca7a6 Added documentation for str.decode().
Fred Drake <fdrake@acm.org>
parents: 21177
diff changeset
569 \code{'strict'}, meaning that encoding errors raise
32459
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
570 \exception{UnicodeError}. Other possible values are \code{'ignore'},
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
571 \code{'replace'} and any other name registered via
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
572 \function{codecs.register_error}.
21332
fbbd8a4ca7a6 Added documentation for str.decode().
Fred Drake <fdrake@acm.org>
parents: 21177
diff changeset
573 \versionadded{2.2}
32459
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
574 \versionchanged[Support for other error handling schemes added]{2.3}
21332
fbbd8a4ca7a6 Added documentation for str.decode().
Fred Drake <fdrake@acm.org>
parents: 21177
diff changeset
575 \end{methoddesc}
fbbd8a4ca7a6 Added documentation for str.decode().
Fred Drake <fdrake@acm.org>
parents: 21177
diff changeset
576
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
577 \begin{methoddesc}[string]{encode}{\optional{encoding\optional{,errors}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
578 Return an encoded version of the string. Default encoding is the current
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
579 default string encoding. \var{errors} may be given to set a different
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
580 error handling scheme. The default for \var{errors} is
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
581 \code{'strict'}, meaning that encoding errors raise a
32459
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
582 \exception{UnicodeError}. Other possible values are \code{'ignore'},
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
583 \code{'replace'}, \code{'xmlcharrefreplace'}, \code{'backslashreplace'}
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
584 and any other name registered via \function{codecs.register_error}.
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
585 For a list of possible encodings, see section~\ref{standard-encodings}.
15332
12aec3381c94 Marc-Andre Lemburg <mal@lemburg.com> noted that the encode() string method
Fred Drake <fdrake@acm.org>
parents: 15005
diff changeset
586 \versionadded{2.0}
32459
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
587 \versionchanged[Support for \code{'xmlcharrefreplace'} and
6b1ea5c07ff7 Document that encode() and decode() raise UnicodeError
Walter Dörwald <walter@livinglogic.de>
parents: 32458
diff changeset
588 \code{'backslashreplace'} and other error handling schemes added]{2.3}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
589 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
590
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
591 \begin{methoddesc}[string]{endswith}{suffix\optional{, start\optional{, end}}}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
592 Return \code{True} if the string ends with the specified \var{suffix},
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
593 otherwise return \code{False}. With optional \var{start}, test beginning at
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
594 that position. With optional \var{end}, stop comparing at that position.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
595 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
596
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
597 \begin{methoddesc}[string]{expandtabs}{\optional{tabsize}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
598 Return a copy of the string where all tab characters are expanded
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
599 using spaces. If \var{tabsize} is not given, a tab size of \code{8}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
600 characters is assumed.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
601 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
602
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
603 \begin{methoddesc}[string]{find}{sub\optional{, start\optional{, end}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
604 Return the lowest index in the string where substring \var{sub} is
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
605 found, such that \var{sub} is contained in the range [\var{start},
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
606 \var{end}). Optional arguments \var{start} and \var{end} are
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
607 interpreted as in slice notation. Return \code{-1} if \var{sub} is
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
608 not found.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
609 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
610
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
611 \begin{methoddesc}[string]{index}{sub\optional{, start\optional{, end}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
612 Like \method{find()}, but raise \exception{ValueError} when the
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
613 substring is not found.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
614 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
615
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
616 \begin{methoddesc}[string]{isalnum}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
617 Return true if all characters in the string are alphanumeric and there
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
618 is at least one character, false otherwise.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
619
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
620 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
621 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
622
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
623 \begin{methoddesc}[string]{isalpha}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
624 Return true if all characters in the string are alphabetic and there
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
625 is at least one character, false otherwise.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
626
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
627 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
628 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
629
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
630 \begin{methoddesc}[string]{isdigit}{}
30707
9e21e56bf5f3 Patch #825679: Clarify semantics of .isfoo on empty strings.
Martin v. Löwis <martin@v.loewis.de>
parents: 30705
diff changeset
631 Return true if all characters in the string are digits and there
9e21e56bf5f3 Patch #825679: Clarify semantics of .isfoo on empty strings.
Martin v. Löwis <martin@v.loewis.de>
parents: 30705
diff changeset
632 is at least one character, false otherwise.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
633
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
634 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
635 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
636
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
637 \begin{methoddesc}[string]{islower}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
638 Return true if all cased characters in the string are lowercase and
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
639 there is at least one cased character, false otherwise.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
640
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
641 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
642 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
643
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
644 \begin{methoddesc}[string]{isspace}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
645 Return true if there are only whitespace characters in the string and
30707
9e21e56bf5f3 Patch #825679: Clarify semantics of .isfoo on empty strings.
Martin v. Löwis <martin@v.loewis.de>
parents: 30705
diff changeset
646 there is at least one character, false otherwise.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
647
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
648 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
649 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
650
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
651 \begin{methoddesc}[string]{istitle}{}
30707
9e21e56bf5f3 Patch #825679: Clarify semantics of .isfoo on empty strings.
Martin v. Löwis <martin@v.loewis.de>
parents: 30705
diff changeset
652 Return true if the string is a titlecased string and there is at least one
30810
2cba0de70df6 Add list.sorted() classmethod.
Raymond Hettinger <python@rcn.com>
parents: 30750
diff changeset
653 character, for example uppercase characters may only follow uncased
30707
9e21e56bf5f3 Patch #825679: Clarify semantics of .isfoo on empty strings.
Martin v. Löwis <martin@v.loewis.de>
parents: 30705
diff changeset
654 characters and lowercase characters only cased ones. Return false
9e21e56bf5f3 Patch #825679: Clarify semantics of .isfoo on empty strings.
Martin v. Löwis <martin@v.loewis.de>
parents: 30705
diff changeset
655 otherwise.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
656
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
657 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
658 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
659
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
660 \begin{methoddesc}[string]{isupper}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
661 Return true if all cased characters in the string are uppercase and
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
662 there is at least one cased character, false otherwise.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
663
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
664 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
665 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
666
32197
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
667 \begin{methoddesc}[string]{iswide}{}
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
668 Return true if all characters in the string are wide or full width and
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
669 there is at least one wide or full width character, false otherwise.
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
670 This method is supported by unicode type only.
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
671 \end{methoddesc}
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
672
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
673 \begin{methoddesc}[string]{join}{seq}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
674 Return a string which is the concatenation of the strings in the
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
675 sequence \var{seq}. The separator between elements is the string
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
676 providing this method.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
677 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
678
31021
21a10c3600b5 Add optional fillchar argument to ljust(), rjust(), and center() string methods.
Raymond Hettinger <python@rcn.com>
parents: 31008
diff changeset
679 \begin{methoddesc}[string]{ljust}{width\optional{, fillchar}}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
680 Return the string left justified in a string of length \var{width}.
31021
21a10c3600b5 Add optional fillchar argument to ljust(), rjust(), and center() string methods.
Raymond Hettinger <python@rcn.com>
parents: 31008
diff changeset
681 Padding is done using the specified \var{fillchar} (default is a
21a10c3600b5 Add optional fillchar argument to ljust(), rjust(), and center() string methods.
Raymond Hettinger <python@rcn.com>
parents: 31008
diff changeset
682 space). The original string is returned if
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
683 \var{width} is less than \code{len(\var{s})}.
31022
845f19b145a8 Add version changed doc for addition of fillchar to ljust/rjust/center
Neal Norwitz <nnorwitz@gmail.com>
parents: 31021
diff changeset
684 \versionchanged[Support for the \var{fillchar} argument]{2.4}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
685 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
686
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
687 \begin{methoddesc}[string]{lower}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
688 Return a copy of the string converted to lowercase.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
689
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
690 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
691 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
692
23017
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
693 \begin{methoddesc}[string]{lstrip}{\optional{chars}}
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
694 Return a copy of the string with leading characters removed. If
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
695 \var{chars} is omitted or \code{None}, whitespace characters are
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
696 removed. If given and not \code{None}, \var{chars} must be a string;
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
697 the characters in the string will be stripped from the beginning of
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
698 the string this method is called on.
26259
60d809a25bae Document that a minor feature was added in 2.2.2. ;-(
Fred Drake <fdrake@acm.org>
parents: 26161
diff changeset
699 \versionchanged[Support for the \var{chars} argument]{2.2.2}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
700 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
701
30750
1d92ecdf2bb1 Avoid confusing name for the 3rd argument to str.replace().
Fred Drake <fdrake@acm.org>
parents: 30737
diff changeset
702 \begin{methoddesc}[string]{replace}{old, new\optional{, count}}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
703 Return a copy of the string with all occurrences of substring
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
704 \var{old} replaced by \var{new}. If the optional argument
30750
1d92ecdf2bb1 Avoid confusing name for the 3rd argument to str.replace().
Fred Drake <fdrake@acm.org>
parents: 30737
diff changeset
705 \var{count} is given, only the first \var{count} occurrences are
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
706 replaced.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
707 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
708
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
709 \begin{methoddesc}[string]{rfind}{sub \optional{,start \optional{,end}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
710 Return the highest index in the string where substring \var{sub} is
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
711 found, such that \var{sub} is contained within s[start,end]. Optional
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
712 arguments \var{start} and \var{end} are interpreted as in slice
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
713 notation. Return \code{-1} on failure.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
714 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
715
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
716 \begin{methoddesc}[string]{rindex}{sub\optional{, start\optional{, end}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
717 Like \method{rfind()} but raises \exception{ValueError} when the
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
718 substring \var{sub} is not found.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
719 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
720
31021
21a10c3600b5 Add optional fillchar argument to ljust(), rjust(), and center() string methods.
Raymond Hettinger <python@rcn.com>
parents: 31008
diff changeset
721 \begin{methoddesc}[string]{rjust}{width\optional{, fillchar}}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
722 Return the string right justified in a string of length \var{width}.
31021
21a10c3600b5 Add optional fillchar argument to ljust(), rjust(), and center() string methods.
Raymond Hettinger <python@rcn.com>
parents: 31008
diff changeset
723 Padding is done using the specified \var{fillchar} (default is a space).
21a10c3600b5 Add optional fillchar argument to ljust(), rjust(), and center() string methods.
Raymond Hettinger <python@rcn.com>
parents: 31008
diff changeset
724 The original string is returned if
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
725 \var{width} is less than \code{len(\var{s})}.
31022
845f19b145a8 Add version changed doc for addition of fillchar to ljust/rjust/center
Neal Norwitz <nnorwitz@gmail.com>
parents: 31021
diff changeset
726 \versionchanged[Support for the \var{fillchar} argument]{2.4}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
727 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
728
31206
3771ff99d5f2 Update documentations for str.rsplit() with Alex Martelli's rewrite.
Hye-Shik Chang <hyeshik@gmail.com>
parents: 31199
diff changeset
729 \begin{methoddesc}[string]{rsplit}{\optional{sep \optional{,maxsplit}}}
3771ff99d5f2 Update documentations for str.rsplit() with Alex Martelli's rewrite.
Hye-Shik Chang <hyeshik@gmail.com>
parents: 31199
diff changeset
730 Return a list of the words in the string, using \var{sep} as the
3771ff99d5f2 Update documentations for str.rsplit() with Alex Martelli's rewrite.
Hye-Shik Chang <hyeshik@gmail.com>
parents: 31199
diff changeset
731 delimiter string. If \var{maxsplit} is given, at most \var{maxsplit}
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
732 splits are done, the \emph{rightmost} ones. If \var{sep} is not specified
31206
3771ff99d5f2 Update documentations for str.rsplit() with Alex Martelli's rewrite.
Hye-Shik Chang <hyeshik@gmail.com>
parents: 31199
diff changeset
733 or \code{None}, any whitespace string is a separator.
31199
504943c89193 Add rsplit method for str and unicode builtin types.
Hye-Shik Chang <hyeshik@gmail.com>
parents: 31022
diff changeset
734 \versionadded{2.4}
504943c89193 Add rsplit method for str and unicode builtin types.
Hye-Shik Chang <hyeshik@gmail.com>
parents: 31022
diff changeset
735 \end{methoddesc}
504943c89193 Add rsplit method for str and unicode builtin types.
Hye-Shik Chang <hyeshik@gmail.com>
parents: 31022
diff changeset
736
23017
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
737 \begin{methoddesc}[string]{rstrip}{\optional{chars}}
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
738 Return a copy of the string with trailing characters removed. If
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
739 \var{chars} is omitted or \code{None}, whitespace characters are
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
740 removed. If given and not \code{None}, \var{chars} must be a string;
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
741 the characters in the string will be stripped from the end of the
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
742 string this method is called on.
26259
60d809a25bae Document that a minor feature was added in 2.2.2. ;-(
Fred Drake <fdrake@acm.org>
parents: 26161
diff changeset
743 \versionchanged[Support for the \var{chars} argument]{2.2.2}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
744 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
745
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
746 \begin{methoddesc}[string]{split}{\optional{sep \optional{,maxsplit}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
747 Return a list of the words in the string, using \var{sep} as the
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
748 delimiter string. If \var{maxsplit} is given, at most \var{maxsplit}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
749 splits are done. If \var{sep} is not specified or \code{None}, any
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
750 whitespace string is a separator.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
751 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
752
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
753 \begin{methoddesc}[string]{splitlines}{\optional{keepends}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
754 Return a list of the lines in the string, breaking at line
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
755 boundaries. Line breaks are not included in the resulting list unless
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
756 \var{keepends} is given and true.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
757 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
758
23017
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
759 \begin{methoddesc}[string]{startswith}{prefix\optional{,
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
760 start\optional{, end}}}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
761 Return \code{True} if string starts with the \var{prefix}, otherwise
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
762 return \code{False}. With optional \var{start}, test string beginning at
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
763 that position. With optional \var{end}, stop comparing string at that
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
764 position.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
765 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
766
23017
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
767 \begin{methoddesc}[string]{strip}{\optional{chars}}
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
768 Return a copy of the string with leading and trailing characters
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
769 removed. If \var{chars} is omitted or \code{None}, whitespace
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
770 characters are removed. If given and not \code{None}, \var{chars}
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
771 must be a string; the characters in the string will be stripped from
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
772 the both ends of the string this method is called on.
26259
60d809a25bae Document that a minor feature was added in 2.2.2. ;-(
Fred Drake <fdrake@acm.org>
parents: 26161
diff changeset
773 \versionchanged[Support for the \var{chars} argument]{2.2.2}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
774 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
775
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
776 \begin{methoddesc}[string]{swapcase}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
777 Return a copy of the string with uppercase characters converted to
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
778 lowercase and vice versa.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
779
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
780 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
781 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
782
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
783 \begin{methoddesc}[string]{title}{}
18416
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make
Fred Drake <fdrake@acm.org>
parents: 18395
diff changeset
784 Return a titlecased version of the string: words start with uppercase
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
785 characters, all remaining cased characters are lowercase.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
786
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
787 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
788 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
789
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
790 \begin{methoddesc}[string]{translate}{table\optional{, deletechars}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
791 Return a copy of the string where all characters occurring in the
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
792 optional argument \var{deletechars} are removed, and the remaining
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
793 characters have been mapped through the given translation table, which
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
794 must be a string of length 256.
29893
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
795
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
796 For Unicode objects, the \method{translate()} method does not
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
797 accept the optional \var{deletechars} argument. Instead, it
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
798 returns a copy of the \var{s} where all characters have been mapped
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
799 through the given translation table which must be a mapping of
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
800 Unicode ordinals to Unicode ordinals, Unicode strings or \code{None}.
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
801 Unmapped characters are left untouched. Characters mapped to \code{None}
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
802 are deleted. Note, a more flexible approach is to create a custom
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
803 character mapping codec using the \refmodule{codecs} module (see
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
804 \module{encodings.cp1251} for an example).
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
805 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
806
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
807 \begin{methoddesc}[string]{upper}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
808 Return a copy of the string converted to uppercase.
32214
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
809
6478eb6ae3c0 Document string methods that are locale-dependent. Fixes #935749.
Martin v. Löwis <martin@v.loewis.de>
parents: 32197
diff changeset
810 For 8-bit strings, this method is locale-dependent.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
811 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
812
32197
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
813 \begin{methoddesc}[string]{width}{}
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
814 Return length of fixed-width representation of the string. This method
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
815 is supported by unicode type only.
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
816 \end{methoddesc}
3a84e23b042f - SF #962502: Add two more methods for unicode type; width() and
Hye-Shik Chang <hyeshik@gmail.com>
parents: 32070
diff changeset
817
23045
8b1268bc371a Apply the second version of SF patch http://www.python.org/sf/536241
Walter Dörwald <walter@livinglogic.de>
parents: 23017
diff changeset
818 \begin{methoddesc}[string]{zfill}{width}
8b1268bc371a Apply the second version of SF patch http://www.python.org/sf/536241
Walter Dörwald <walter@livinglogic.de>
parents: 23017
diff changeset
819 Return the numeric string left filled with zeros in a string
8b1268bc371a Apply the second version of SF patch http://www.python.org/sf/536241
Walter Dörwald <walter@livinglogic.de>
parents: 23017
diff changeset
820 of length \var{width}. The original string is returned if
8b1268bc371a Apply the second version of SF patch http://www.python.org/sf/536241
Walter Dörwald <walter@livinglogic.de>
parents: 23017
diff changeset
821 \var{width} is less than \code{len(\var{s})}.
26260
b327ffcfe9b7 Better note that str.zfill() was added in 2.2.2 as well. ;-(
Fred Drake <fdrake@acm.org>
parents: 26259
diff changeset
822 \versionadded{2.2.2}
23045
8b1268bc371a Apply the second version of SF patch http://www.python.org/sf/536241
Walter Dörwald <walter@livinglogic.de>
parents: 23017
diff changeset
823 \end{methoddesc}
8b1268bc371a Apply the second version of SF patch http://www.python.org/sf/536241
Walter Dörwald <walter@livinglogic.de>
parents: 23017
diff changeset
824
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
825
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
826 \subsubsection{String Formatting Operations \label{typesseq-strings}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
827
21177
7d1eac41ce3e Slightly improved indexing for the string-% operator, thanks to comments
Fred Drake <fdrake@acm.org>
parents: 21163
diff changeset
828 \index{formatting, string (\%{})}
21542
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
829 \index{interpolation, string (\%{})}
14552
a8d1c030b19f Add some index entries to make it easier to find information on
Fred Drake <fdrake@acm.org>
parents: 14520
diff changeset
830 \index{string!formatting}
21542
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
831 \index{string!interpolation}
14552
a8d1c030b19f Add some index entries to make it easier to find information on
Fred Drake <fdrake@acm.org>
parents: 14520
diff changeset
832 \index{printf-style formatting}
a8d1c030b19f Add some index entries to make it easier to find information on
Fred Drake <fdrake@acm.org>
parents: 14520
diff changeset
833 \index{sprintf-style formatting}
21177
7d1eac41ce3e Slightly improved indexing for the string-% operator, thanks to comments
Fred Drake <fdrake@acm.org>
parents: 21163
diff changeset
834 \index{\protect\%{} formatting}
21542
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
835 \index{\protect\%{} interpolation}
14552
a8d1c030b19f Add some index entries to make it easier to find information on
Fred Drake <fdrake@acm.org>
parents: 14520
diff changeset
836
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
837 String and Unicode objects have one unique built-in operation: the
21542
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
838 \code{\%} operator (modulo). This is also known as the string
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
839 \emph{formatting} or \emph{interpolation} operator. Given
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
840 \code{\var{format} \% \var{values}} (where \var{format} is a string or
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
841 Unicode object), \code{\%} conversion specifications in \var{format}
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
842 are replaced with zero or more elements of \var{values}. The effect
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
843 is similar to the using \cfunction{sprintf()} in the C language. If
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
844 \var{format} is a Unicode object, or if any of the objects being
5d4135609efc Added index entries similar to some recommended by Skip, and used the word
Fred Drake <fdrake@acm.org>
parents: 21332
diff changeset
845 converted using the \code{\%s} conversion are Unicode objects, the
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
846 result will also be a Unicode object.
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
847
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
848 If \var{format} requires a single argument, \var{values} may be a
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
849 single non-tuple object.\footnote{To format only a tuple you
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
850 should therefore provide a singleton tuple whose only element
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
851 is the tuple to be formatted.} Otherwise, \var{values} must be a tuple with
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
852 exactly the number of items specified by the format string, or a
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
853 single mapping object (for example, a dictionary).
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
854
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
855 A conversion specifier contains two or more characters and has the
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
856 following components, which must occur in this order:
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
857
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
858 \begin{enumerate}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
859 \item The \character{\%} character, which marks the start of the
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
860 specifier.
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
861 \item Mapping key (optional), consisting of a parenthesised sequence
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
862 of characters (for example, \code{(somename)}).
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
863 \item Conversion flags (optional), which affect the result of some
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
864 conversion types.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
865 \item Minimum field width (optional). If specified as an
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
866 \character{*} (asterisk), the actual width is read from the
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
867 next element of the tuple in \var{values}, and the object to
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
868 convert comes after the minimum field width and optional
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
869 precision.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
870 \item Precision (optional), given as a \character{.} (dot) followed
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
871 by the precision. If specified as \character{*} (an
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
872 asterisk), the actual width is read from the next element of
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
873 the tuple in \var{values}, and the value to convert comes after
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
874 the precision.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
875 \item Length modifier (optional).
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
876 \item Conversion type.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
877 \end{enumerate}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
878
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
879 When the right argument is a dictionary (or other mapping type), then
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
880 the formats in the string \emph{must} include a parenthesised mapping key into
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
881 that dictionary inserted immediately after the \character{\%}
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
882 character. The mapping key selects the value to be formatted from the
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
883 mapping. For example:
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
884
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
885 \begin{verbatim}
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
886 >>> print '%(language)s has %(#)03d quote types.' % \
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
887 {'language': "Python", "#": 2}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
888 Python has 002 quote types.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
889 \end{verbatim}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
890
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
891 In this case no \code{*} specifiers may occur in a format (since they
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
892 require a sequential parameter list).
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
893
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
894 The conversion flag characters are:
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
895
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
896 \begin{tableii}{c|l}{character}{Flag}{Meaning}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
897 \lineii{\#}{The value conversion will use the ``alternate form''
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
898 (where defined below).}
27919
4b5c2e025c5e Fix SF bug #687655, String formatting conversions misleading
Neal Norwitz <nnorwitz@gmail.com>
parents: 27225
diff changeset
899 \lineii{0}{The conversion will be zero padded for numeric values.}
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
900 \lineii{-}{The converted value is left adjusted (overrides
25906
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
901 the \character{0} conversion if both are given).}
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
902 \lineii{{~}}{(a space) A blank should be left before a positive number
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
903 (or empty string) produced by a signed conversion.}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
904 \lineii{+}{A sign character (\character{+} or \character{-}) will
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
905 precede the conversion (overrides a "space" flag).}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
906 \end{tableii}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
907
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
908 The length modifier may be \code{h}, \code{l}, and \code{L} may be
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
909 present, but are ignored as they are not necessary for Python.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
910
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
911 The conversion types are:
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
912
25906
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
913 \begin{tableiii}{c|l|c}{character}{Conversion}{Meaning}{Notes}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
914 \lineiii{d}{Signed integer decimal.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
915 \lineiii{i}{Signed integer decimal.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
916 \lineiii{o}{Unsigned octal.}{(1)}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
917 \lineiii{u}{Unsigned decimal.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
918 \lineiii{x}{Unsigned hexidecimal (lowercase).}{(2)}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
919 \lineiii{X}{Unsigned hexidecimal (uppercase).}{(2)}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
920 \lineiii{e}{Floating point exponential format (lowercase).}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
921 \lineiii{E}{Floating point exponential format (uppercase).}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
922 \lineiii{f}{Floating point decimal format.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
923 \lineiii{F}{Floating point decimal format.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
924 \lineiii{g}{Same as \character{e} if exponent is greater than -4 or
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
925 less than precision, \character{f} otherwise.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
926 \lineiii{G}{Same as \character{E} if exponent is greater than -4 or
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
927 less than precision, \character{F} otherwise.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
928 \lineiii{c}{Single character (accepts integer or single character
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
929 string).}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
930 \lineiii{r}{String (converts any python object using
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
931 \function{repr()}).}{(3)}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
932 \lineiii{s}{String (converts any python object using
27225
5d42dba49fe5 SF patch 664183 and SF bug 664044: Note that both u'%s' % 'x' and
Raymond Hettinger <python@rcn.com>
parents: 27036
diff changeset
933 \function{str()}).}{(4)}
25906
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
934 \lineiii{\%}{No argument is converted, results in a \character{\%}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
935 character in the result.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
936 \end{tableiii}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
937
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
938 \noindent
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
939 Notes:
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
940 \begin{description}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
941 \item[(1)]
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
942 The alternate form causes a leading zero (\character{0}) to be
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
943 inserted between left-hand padding and the formatting of the
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
944 number if the leading character of the result is not already a
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
945 zero.
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
946 \item[(2)]
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
947 The alternate form causes a leading \code{'0x'} or \code{'0X'}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
948 (depending on whether the \character{x} or \character{X} format
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
949 was used) to be inserted between left-hand padding and the
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
950 formatting of the number if the leading character of the result is
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
951 not already a zero.
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
952 \item[(3)]
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
953 The \code{\%r} conversion was added in Python 2.0.
27225
5d42dba49fe5 SF patch 664183 and SF bug 664044: Note that both u'%s' % 'x' and
Raymond Hettinger <python@rcn.com>
parents: 27036
diff changeset
954 \item[(4)]
5d42dba49fe5 SF patch 664183 and SF bug 664044: Note that both u'%s' % 'x' and
Raymond Hettinger <python@rcn.com>
parents: 27036
diff changeset
955 If the object or format provided is a \class{unicode} string,
5d42dba49fe5 SF patch 664183 and SF bug 664044: Note that both u'%s' % 'x' and
Raymond Hettinger <python@rcn.com>
parents: 27036
diff changeset
956 the resulting string will also be \class{unicode}.
25906
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
957 \end{description}
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
958
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
959 % XXX Examples?
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
960
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
961 Since Python strings have an explicit length, \code{\%s} conversions
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
962 do not assume that \code{'\e0'} is the end of the string.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
963
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
964 For safety reasons, floating point precisions are clipped to 50;
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
965 \code{\%f} conversions for numbers whose absolute value is over 1e25
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
966 are replaced by \code{\%g} conversions.\footnote{
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
967 These numbers are fairly arbitrary. They are intended to
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
968 avoid printing endless strings of meaningless digits without hampering
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
969 correct use and without having to know the exact precision of floating
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
970 point values on a particular machine.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
971 } All other errors raise exceptions.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
972
21163
7b6879714b74 Make no assumption about how modules are built when referring to them; this
Fred Drake <fdrake@acm.org>
parents: 21159
diff changeset
973 Additional string operations are defined in standard modules
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
974 \refmodule{string}\refstmodindex{string}\ and
22241
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
975 \refmodule{re}.\refstmodindex{re}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
976
13967
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
977
14044
a905c5aa0691 As pointed out by Denis S. Otkidach <den@analyt.chem.msu.ru>, xrange()
Fred Drake <fdrake@acm.org>
parents: 13967
diff changeset
978 \subsubsection{XRange Type \label{typesseq-xrange}}
13967
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
979
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
980 The \class{xrange}\obindex{xrange} type is an immutable sequence which
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
981 is commonly used for looping. The advantage of the \class{xrange}
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
982 type is that an \class{xrange} object will always take the same amount
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
983 of memory, no matter the size of the range it represents. There are
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
984 no consistent performance advantages.
13967
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
985
26592
0c646baeec58 Update comments about the performance of xrange().
Raymond Hettinger <python@rcn.com>
parents: 26514
diff changeset
986 XRange objects have very little behavior: they only support indexing,
0c646baeec58 Update comments about the performance of xrange().
Raymond Hettinger <python@rcn.com>
parents: 26514
diff changeset
987 iteration, and the \function{len()} function.
13967
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
988
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
989
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
990 \subsubsection{Mutable Sequence Types \label{typesseq-mutable}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
991
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
992 List objects support additional operations that allow in-place
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
993 modification of the object.
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
994 Other mutable sequence types (when added to the language) should
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
995 also support these operations.
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
996 Strings and tuples are immutable sequence types: such objects cannot
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
997 be modified once created.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
998 The following operations are defined on mutable sequence types (where
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
999 \var{x} is an arbitrary object):
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1000 \indexiii{mutable}{sequence}{types}
15005
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
1001 \obindex{list}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1002
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1003 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1004 \lineiii{\var{s}[\var{i}] = \var{x}}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1005 {item \var{i} of \var{s} is replaced by \var{x}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1006 \lineiii{\var{s}[\var{i}:\var{j}] = \var{t}}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1007 {slice of \var{s} from \var{i} to \var{j} is replaced by \var{t}}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1008 \lineiii{del \var{s}[\var{i}:\var{j}]}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1009 {same as \code{\var{s}[\var{i}:\var{j}] = []}}{}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1010 \lineiii{\var{s}[\var{i}:\var{j}:\var{k}] = \var{t}}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1011 {the elements of \code{\var{s}[\var{i}:\var{j}:\var{k}]} are replaced by those of \var{t}}{(1)}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1012 \lineiii{del \var{s}[\var{i}:\var{j}:\var{k}]}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1013 {removes the elements of \code{\var{s}[\var{i}:\var{j}:\var{k}]} from the list}{}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1014 \lineiii{\var{s}.append(\var{x})}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1015 {same as \code{\var{s}[len(\var{s}):len(\var{s})] = [\var{x}]}}{(2)}
9318
8a26e55e18b8 Document the new list.extend() method. Interesting enough, the
Barry Warsaw <barry@python.org>
parents: 9083
diff changeset
1016 \lineiii{\var{s}.extend(\var{x})}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1017 {same as \code{\var{s}[len(\var{s}):len(\var{s})] = \var{x}}}{(3)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1018 \lineiii{\var{s}.count(\var{x})}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1019 {return number of \var{i}'s for which \code{\var{s}[\var{i}] == \var{x}}}{}
29516
d761ff55b3be Updated documentation for the new slice arguments for list.index().
Walter Dörwald <walter@livinglogic.de>
parents: 29343
diff changeset
1020 \lineiii{\var{s}.index(\var{x}\optional{, \var{i}\optional{, \var{j}}})}
d761ff55b3be Updated documentation for the new slice arguments for list.index().
Walter Dörwald <walter@livinglogic.de>
parents: 29343
diff changeset
1021 {return smallest \var{k} such that \code{\var{s}[\var{k}] == \var{x}} and
d761ff55b3be Updated documentation for the new slice arguments for list.index().
Walter Dörwald <walter@livinglogic.de>
parents: 29343
diff changeset
1022 \code{\var{i} <= \var{k} < \var{j}}}{(4)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1023 \lineiii{\var{s}.insert(\var{i}, \var{x})}
28606
436d812f2b94 - list.insert(i, x) now interprets negative i as it would be
Guido van Rossum <guido@python.org>
parents: 28337
diff changeset
1024 {same as \code{\var{s}[\var{i}:\var{i}] = [\var{x}]}}{(5)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1025 \lineiii{\var{s}.pop(\optional{\var{i}})}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1026 {same as \code{\var{x} = \var{s}[\var{i}]; del \var{s}[\var{i}]; return \var{x}}}{(6)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1027 \lineiii{\var{s}.remove(\var{x})}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1028 {same as \code{del \var{s}[\var{s}.index(\var{x})]}}{(4)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1029 \lineiii{\var{s}.reverse()}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1030 {reverses the items of \var{s} in place}{(7)}
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1031 \lineiii{\var{s}.sort(\optional{\var{cmp}\optional{,
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1032 \var{key}\optional{, \var{reverse}}}})}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1033 {sort the items of \var{s} in place}{(7), (8), (9), (10)}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1034 \end{tableiii}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1035 \indexiv{operations on}{mutable}{sequence}{types}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1036 \indexiii{operations on}{sequence}{types}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1037 \indexiii{operations on}{list}{type}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1038 \indexii{subscript}{assignment}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1039 \indexii{slice}{assignment}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1040 \indexii{extended slice}{assignment}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1041 \stindex{del}
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1042 \withsubitem{(list method)}{
11183
1e0b1967be7f In note mentioning [].remove()'s exception, tell what exception is
Fred Drake <fdrake@acm.org>
parents: 11100
diff changeset
1043 \ttindex{append()}\ttindex{extend()}\ttindex{count()}\ttindex{index()}
1e0b1967be7f In note mentioning [].remove()'s exception, tell what exception is
Fred Drake <fdrake@acm.org>
parents: 11100
diff changeset
1044 \ttindex{insert()}\ttindex{pop()}\ttindex{remove()}\ttindex{reverse()}
9523
ed6cacddc6c6 Fix indexing of func_code attribute; this is on a function, not a code
Fred Drake <fdrake@acm.org>
parents: 9461
diff changeset
1045 \ttindex{sort()}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1046 \noindent
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1047 Notes:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1048 \begin{description}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1049 \item[(1)] \var{t} must have the same length as the slice it is
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1050 replacing.
23778
245224d1b8c9 This is my nearly two year old patch
Michael W. Hudson <mwh@python.net>
parents: 23515
diff changeset
1051
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1052 \item[(2)] The C implementation of Python has historically accepted
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1053 multiple parameters and implicitly joined them into a tuple; this
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1054 no longer works in Python 2.0. Use of this misfeature has been
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1055 deprecated since Python 1.4.
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
1056
31357
c088584f5533 SF bug #872461: list.extend() described as experimental
Raymond Hettinger <python@rcn.com>
parents: 31298
diff changeset
1057 \item[(3)] Raises an exception when \var{x} is not a list object.
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1058
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1059 \item[(4)] Raises \exception{ValueError} when \var{x} is not found in
29516
d761ff55b3be Updated documentation for the new slice arguments for list.index().
Walter Dörwald <walter@livinglogic.de>
parents: 29343
diff changeset
1060 \var{s}. When a negative index is passed as the second or third parameter
d761ff55b3be Updated documentation for the new slice arguments for list.index().
Walter Dörwald <walter@livinglogic.de>
parents: 29343
diff changeset
1061 to the \method{index()} method, the list length is added, as for slice
d761ff55b3be Updated documentation for the new slice arguments for list.index().
Walter Dörwald <walter@livinglogic.de>
parents: 29343
diff changeset
1062 indices. If it is still negative, it is truncated to zero, as for
d761ff55b3be Updated documentation for the new slice arguments for list.index().
Walter Dörwald <walter@livinglogic.de>
parents: 29343
diff changeset
1063 slice indices. \versionchanged[Previously, \method{index()} didn't
d761ff55b3be Updated documentation for the new slice arguments for list.index().
Walter Dörwald <walter@livinglogic.de>
parents: 29343
diff changeset
1064 have arguments for specifying start and stop positions]{2.3}
11183
1e0b1967be7f In note mentioning [].remove()'s exception, tell what exception is
Fred Drake <fdrake@acm.org>
parents: 11100
diff changeset
1065
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1066 \item[(5)] When a negative index is passed as the first parameter to
28606
436d812f2b94 - list.insert(i, x) now interprets negative i as it would be
Guido van Rossum <guido@python.org>
parents: 28337
diff changeset
1067 the \method{insert()} method, the list length is added, as for slice
436d812f2b94 - list.insert(i, x) now interprets negative i as it would be
Guido van Rossum <guido@python.org>
parents: 28337
diff changeset
1068 indices. If it is still negative, it is truncated to zero, as for
436d812f2b94 - list.insert(i, x) now interprets negative i as it would be
Guido van Rossum <guido@python.org>
parents: 28337
diff changeset
1069 slice indices. \versionchanged[Previously, all negative indices
436d812f2b94 - list.insert(i, x) now interprets negative i as it would be
Guido van Rossum <guido@python.org>
parents: 28337
diff changeset
1070 were truncated to zero]{2.3}
20701
5f6850d1f9e8 Explain what [].insert() does when the target index is negative.
Fred Drake <fdrake@acm.org>
parents: 20580
diff changeset
1071
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1072 \item[(6)] The \method{pop()} method is only supported by the list and
13777
b3903e05017f Stop lying about [].pop() being experimental! There is no backing it out
Fred Drake <fdrake@acm.org>
parents: 13772
diff changeset
1073 array types. The optional argument \var{i} defaults to \code{-1},
b3903e05017f Stop lying about [].pop() being experimental! There is no backing it out
Fred Drake <fdrake@acm.org>
parents: 13772
diff changeset
1074 so that by default the last item is removed and returned.
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
1075
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1076 \item[(7)] The \method{sort()} and \method{reverse()} methods modify the
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
1077 list in place for economy of space when sorting or reversing a large
18829
1bc1fdf1482b trivial rewording in footnote 5.
Skip Montanaro <skip@pobox.com>
parents: 18416
diff changeset
1078 list. To remind you that they operate by side effect, they don't return
1bc1fdf1482b trivial rewording in footnote 5.
Skip Montanaro <skip@pobox.com>
parents: 18416
diff changeset
1079 the sorted or reversed list.
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
1080
31210
c06b570adf12 Guido grants a Christmas wish:
Raymond Hettinger <python@rcn.com>
parents: 31206
diff changeset
1081 \item[(8)] The \method{sort()} method takes optional arguments for
c06b570adf12 Guido grants a Christmas wish:
Raymond Hettinger <python@rcn.com>
parents: 31206
diff changeset
1082 controlling the comparisions.
30697
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1083
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1084 \var{cmp} specifies a custom comparison function of two arguments
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1085 (list items) which should return a negative, zero or positive number
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1086 depending on whether the first argument is considered smaller than,
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1087 equal to, or larger than the second argument:
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1088 \samp{\var{cmp}=\keyword{lambda} \var{x},\var{y}:
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1089 \function{cmp}(x.lower(), y.lower())}
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1090
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1091 \var{key} specifies a function of one argument that is used to
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1092 extract a comparison key from each list element:
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1093 \samp{\var{cmp}=\function{str.lower}}
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1094
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1095 \var{reverse} is a boolean value. If set to \code{True}, then the
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1096 list elements are sorted as if each comparison were reversed.
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1097
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1098 In general, the \var{key} and \var{reverse} conversion processes are
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1099 much faster than specifying an equivalent \var{cmp} function. This is
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1100 because \var{cmp} is called multiple times for each list element while
30737
38b0b7d41936 markup fixes; this would not format
Fred Drake <fdrake@acm.org>
parents: 30707
diff changeset
1101 \var{key} and \var{reverse} touch each element only once.
30697
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1102
28337
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1103 \versionchanged[Support for \code{None} as an equivalent to omitting
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1104 \var{cmp} was added]{2.3}
28337
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1105
30737
38b0b7d41936 markup fixes; this would not format
Fred Drake <fdrake@acm.org>
parents: 30707
diff changeset
1106 \versionchanged[Support for \var{key} and \var{reverse} was added]{2.4}
28337
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1107
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1108 \item[(9)] Starting with Python 2.3, the \method{sort()} method is
31210
c06b570adf12 Guido grants a Christmas wish:
Raymond Hettinger <python@rcn.com>
parents: 31206
diff changeset
1109 guaranteed to be stable. A sort is stable if it guarantees not to
30697
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1110 change the relative order of elements that compare equal --- this is
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1111 helpful for sorting in multiple passes (for example, sort by
1345c23a0591 * list.sort() now supports three keyword arguments: cmp, key, and reverse.
Raymond Hettinger <python@rcn.com>
parents: 30413
diff changeset
1112 department, then by salary grade).
26161
dd10d97d329a SF patch 637176: list.sort crasher
Tim Peters <tim.peters@gmail.com>
parents: 25906
diff changeset
1113
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1114 \item[(10)] While a list is being sorted, the effect of attempting to
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1115 mutate, or even inspect, the list is undefined. The C
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1116 implementation of Python 2.3 and newer makes the list appear empty
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1117 for the duration, and raises \exception{ValueError} if it can detect
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1118 that the list has been mutated during a sort.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1119 \end{description}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1120
31008
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1121 \subsection{Set Types \label{types-set}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1122 \obindex{set}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1123
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1124 A \dfn{set} object is an unordered collection of immutable values.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1125 Common uses include membership testing, removing duplicates from a sequence,
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1126 and computing mathematical operations such as intersection, union, difference,
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1127 and symmetric difference.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1128 \versionadded{2.4}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1129
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1130 Like other collections, sets support \code{\var{x} in \var{set}},
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1131 \code{len(\var{set})}, and \code{for \var{x} in \var{set}}. Being an
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1132 unordered collection, sets do not record element position or order of
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1133 insertion. Accordingly, sets do not support indexing, slicing, or
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1134 other sequence-like behavior.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1135
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1136 There are currently two builtin set types, \class{set} and \class{frozenset}.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1137 The \class{set} type is mutable --- the contents can be changed using methods
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1138 like \method{add()} and \method{remove()}. Since it is mutable, it has no
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1139 hash value and cannot be used as either a dictionary key or as an element of
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1140 another set. The \class{frozenset} type is immutable and hashable --- its
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1141 contents cannot be altered after is created; however, it can be used as
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1142 a dictionary key or as an element of another set.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1143
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1144 Instances of \class{set} and \class{frozenset} provide the following operations:
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1145
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1146 \begin{tableiii}{c|c|l}{code}{Operation}{Equivalent}{Result}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1147 \lineiii{len(\var{s})}{}{cardinality of set \var{s}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1148
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1149 \hline
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1150 \lineiii{\var{x} in \var{s}}{}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1151 {test \var{x} for membership in \var{s}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1152 \lineiii{\var{x} not in \var{s}}{}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1153 {test \var{x} for non-membership in \var{s}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1154 \lineiii{\var{s}.issubset(\var{t})}{\code{\var{s} <= \var{t}}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1155 {test whether every element in \var{s} is in \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1156 \lineiii{\var{s}.issuperset(\var{t})}{\code{\var{s} >= \var{t}}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1157 {test whether every element in \var{t} is in \var{s}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1158
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1159 \hline
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1160 \lineiii{\var{s}.union(\var{t})}{\var{s} | \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1161 {new set with elements from both \var{s} and \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1162 \lineiii{\var{s}.intersection(\var{t})}{\var{s} \&\ \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1163 {new set with elements common to \var{s} and \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1164 \lineiii{\var{s}.difference(\var{t})}{\var{s} - \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1165 {new set with elements in \var{s} but not in \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1166 \lineiii{\var{s}.symmetric_difference(\var{t})}{\var{s} \^\ \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1167 {new set with elements in either \var{s} or \var{t} but not both}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1168 \lineiii{\var{s}.copy()}{}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1169 {new set with a shallow copy of \var{s}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1170 \end{tableiii}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1171
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1172 Note, the non-operator versions of \method{union()}, \method{intersection()},
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1173 \method{difference()}, and \method{symmetric_difference()},
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1174 \method{issubset()}, and \method{issuperset()} methods will accept any
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1175 iterable as an argument. In contrast, their operator based counterparts
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1176 require their arguments to be sets. This precludes error-prone constructions
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1177 like \code{set('abc') \&\ 'cbs'} in favor of the more readable
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1178 \code{set('abc').intersection('cbs')}.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1179
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1180 Both \class{set} and \class{frozenset} support set to set comparisons.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1181 Two sets are equal if and only if every element of each set is contained in
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1182 the other (each is a subset of the other).
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1183 A set is less than another set if and only if the first set is a proper
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1184 subset of the second set (is a subset, but is not equal).
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1185 A set is greater than another set if and only if the first set is a proper
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1186 superset of the second set (is a superset, but is not equal).
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1187
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1188 The subset and equality comparisons do not generalize to a complete
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1189 ordering function. For example, any two disjoint sets are not equal and
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1190 are not subsets of each other, so \emph{all} of the following return
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1191 \code{False}: \code{\var{a}<\var{b}}, \code{\var{a}==\var{b}}, or
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1192 \code{\var{a}>\var{b}}.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1193 Accordingly, sets do not implement the \method{__cmp__} method.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1194
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1195 Since sets only define partial ordering (subset relationships), the output
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1196 of the \method{list.sort()} method is undefined for lists of sets.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1197
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1198 For convenience in implementing sets of sets, the \method{__contains__()},
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1199 \method{remove()}, and \method{discard()} methods automatically match
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1200 instances of the \class{set} class their \class{frozenset} counterparts
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1201 inside a set. For example, \code{set('abc') in set([frozenset('abc')])}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1202 returns \code{True}.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1203
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1204 The following table lists operations available for \class{set}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1205 that do not apply to immutable instances of \class{frozenset}:
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1206
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1207 \begin{tableiii}{c|c|l}{code}{Operation}{Equivalent}{Result}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1208 \lineiii{\var{s}.update(\var{t})}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1209 {\var{s} |= \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1210 {return set \var{s} with elements added from \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1211 \lineiii{\var{s}.intersection_update(\var{t})}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1212 {\var{s} \&= \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1213 {return set \var{s} keeping only elements also found in \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1214 \lineiii{\var{s}.difference_update(\var{t})}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1215 {\var{s} -= \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1216 {return set \var{s} after removing elements found in \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1217 \lineiii{\var{s}.symmetric_difference_update(\var{t})}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1218 {\var{s} \textasciicircum= \var{t}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1219 {return set \var{s} with elements from \var{s} or \var{t}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1220 but not both}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1221
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1222 \hline
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1223 \lineiii{\var{s}.add(\var{x})}{}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1224 {add element \var{x} to set \var{s}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1225 \lineiii{\var{s}.remove(\var{x})}{}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1226 {remove \var{x} from set \var{s}; raises KeyError if not present}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1227 \lineiii{\var{s}.discard(\var{x})}{}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1228 {removes \var{x} from set \var{s} if present}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1229 \lineiii{\var{s}.pop()}{}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1230 {remove and return an arbitrary element from \var{s}; raises
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1231 \exception{KeyError} if empty}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1232 \lineiii{\var{s}.clear()}{}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1233 {remove all elements from set \var{s}}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1234 \end{tableiii}
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1235
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1236 Note, the non-operator versions of the \method{update()},
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1237 \method{intersection_update()}, \method{difference_update()}, and
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1238 \method{symmetric_difference_update()} methods will accept any iterable
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1239 as an argument.
4224d807911c * Checkin remaining documentation
Raymond Hettinger <python@rcn.com>
parents: 30813
diff changeset
1240
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1241
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
1242 \subsection{Mapping Types \label{typesmapping}}
15005
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
1243 \obindex{mapping}
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
1244 \obindex{dictionary}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1245
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1246 A \dfn{mapping} object maps immutable values to
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1247 arbitrary objects. Mappings are mutable objects. There is currently
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1248 only one standard mapping type, the \dfn{dictionary}. A dictionary's keys are
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1249 almost arbitrary values. Only values containing lists, dictionaries
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1250 or other mutable types (that are compared by value rather than by
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1251 object identity) may not be used as keys.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1252 Numeric types used for keys obey the normal rules for numeric
30413
53f1c32ee69d SF bug #804280: fromkeys is not listed in index
Raymond Hettinger <python@rcn.com>
parents: 30375
diff changeset
1253 comparison: if two numbers compare equal (such as \code{1} and
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1254 \code{1.0}) then they can be used interchangeably to index the same
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1255 dictionary entry.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1256
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1257 Dictionaries are created by placing a comma-separated list of
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1258 \code{\var{key}: \var{value}} pairs within braces, for example:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1259 \code{\{'jack': 4098, 'sjoerd': 4127\}} or
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1260 \code{\{4098: 'jack', 4127: 'sjoerd'\}}.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1261
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1262 The following operations are defined on mappings (where \var{a} and
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1263 \var{b} are mappings, \var{k} is a key, and \var{v} and \var{x} are
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1264 arbitrary objects):
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1265 \indexiii{operations on}{mapping}{types}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1266 \indexiii{operations on}{dictionary}{type}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1267 \stindex{del}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1268 \bifuncindex{len}
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1269 \withsubitem{(dictionary method)}{
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1270 \ttindex{clear()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1271 \ttindex{copy()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1272 \ttindex{has_key()}
30413
53f1c32ee69d SF bug #804280: fromkeys is not listed in index
Raymond Hettinger <python@rcn.com>
parents: 30375
diff changeset
1273 \ttindex{fromkeys()}
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1274 \ttindex{items()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1275 \ttindex{keys()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1276 \ttindex{update()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1277 \ttindex{values()}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1278 \ttindex{get()}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1279 \ttindex{setdefault()}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1280 \ttindex{pop()}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1281 \ttindex{popitem()}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1282 \ttindex{iteritems()}
29067
04065c4a1c6b Missing parenthesis found by texcheck.py
Raymond Hettinger <python@rcn.com>
parents: 29065
diff changeset
1283 \ttindex{iterkeys()}
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1284 \ttindex{itervalues()}}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1285
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1286 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1287 \lineiii{len(\var{a})}{the number of items in \var{a}}{}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1288 \lineiii{\var{a}[\var{k}]}{the item of \var{a} with key \var{k}}{(1)}
13764
fdbc8730d356 Two minor nits from Gerry Weiner (no working email address) about
Fred Drake <fdrake@acm.org>
parents: 13222
diff changeset
1289 \lineiii{\var{a}[\var{k}] = \var{v}}
fdbc8730d356 Two minor nits from Gerry Weiner (no working email address) about
Fred Drake <fdrake@acm.org>
parents: 13222
diff changeset
1290 {set \code{\var{a}[\var{k}]} to \var{v}}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1291 {}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1292 \lineiii{del \var{a}[\var{k}]}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1293 {remove \code{\var{a}[\var{k}]} from \var{a}}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1294 {(1)}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1295 \lineiii{\var{a}.clear()}{remove all items from \code{a}}{}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1296 \lineiii{\var{a}.copy()}{a (shallow) copy of \code{a}}{}
17616
7acba78e1e09 At the suggestion of Peter Funk, document 'key in dict' and 'key not
Guido van Rossum <guido@python.org>
parents: 17612
diff changeset
1297 \lineiii{\var{a}.has_key(\var{k})}
30095
e3c9b48de60a SF bug #775836: change 0,1 to False,True in dict.has_key doc
Raymond Hettinger <python@rcn.com>
parents: 29893
diff changeset
1298 {\code{True} if \var{a} has a key \var{k}, else \code{False}}
17594
bf94af396b1e Implement, test and document "key in dict" and "key not in dict".
Guido van Rossum <guido@python.org>
parents: 16778
diff changeset
1299 {}
17616
7acba78e1e09 At the suggestion of Peter Funk, document 'key in dict' and 'key not
Guido van Rossum <guido@python.org>
parents: 17612
diff changeset
1300 \lineiii{\var{k} \code{in} \var{a}}
7acba78e1e09 At the suggestion of Peter Funk, document 'key in dict' and 'key not
Guido van Rossum <guido@python.org>
parents: 17612
diff changeset
1301 {Equivalent to \var{a}.has_key(\var{k})}
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1302 {(2)}
17594
bf94af396b1e Implement, test and document "key in dict" and "key not in dict".
Guido van Rossum <guido@python.org>
parents: 16778
diff changeset
1303 \lineiii{\var{k} not in \var{a}}
17616
7acba78e1e09 At the suggestion of Peter Funk, document 'key in dict' and 'key not
Guido van Rossum <guido@python.org>
parents: 17612
diff changeset
1304 {Equivalent to \code{not} \var{a}.has_key(\var{k})}
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1305 {(2)}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1306 \lineiii{\var{a}.items()}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1307 {a copy of \var{a}'s list of (\var{key}, \var{value}) pairs}
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1308 {(3)}
18085
7e459fb3c332 Fixed reference to table notes for {}.keys() and {}.items() -- these
Fred Drake <fdrake@acm.org>
parents: 17966
diff changeset
1309 \lineiii{\var{a}.keys()}{a copy of \var{a}'s list of keys}{(3)}
31616
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1310 \lineiii{\var{a}.update(\optional{\var{b}})}
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1311 {updates (and overwrites) key/value pairs from \var{b}}
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1312 {(9)}
26437
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1313 \lineiii{\var{a}.fromkeys(\var{seq}\optional{, \var{value}})}
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1314 {Creates a new dictionary with keys from \var{seq} and values set to \var{value}}
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1315 {(7)}
18085
7e459fb3c332 Fixed reference to table notes for {}.keys() and {}.items() -- these
Fred Drake <fdrake@acm.org>
parents: 17966
diff changeset
1316 \lineiii{\var{a}.values()}{a copy of \var{a}'s list of values}{(3)}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1317 \lineiii{\var{a}.get(\var{k}\optional{, \var{x}})}
17603
d638e419c304 Fix a number of minor markup errors.
Fred Drake <fdrake@acm.org>
parents: 17594
diff changeset
1318 {\code{\var{a}[\var{k}]} if \code{\var{k} in \var{a}},
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1319 else \var{x}}
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1320 {(4)}
13894
77b9e041b595 Barry's patch to document the new setdefault() method. Slightly
Guido van Rossum <guido@python.org>
parents: 13780
diff changeset
1321 \lineiii{\var{a}.setdefault(\var{k}\optional{, \var{x}})}
17603
d638e419c304 Fix a number of minor markup errors.
Fred Drake <fdrake@acm.org>
parents: 17594
diff changeset
1322 {\code{\var{a}[\var{k}]} if \code{\var{k} in \var{a}},
13894
77b9e041b595 Barry's patch to document the new setdefault() method. Slightly
Guido van Rossum <guido@python.org>
parents: 13780
diff changeset
1323 else \var{x} (also setting it)}
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1324 {(5)}
28211
92e3b611dc9f SF patch #693753: fix for bug 639806: default for dict.pop
Raymond Hettinger <python@rcn.com>
parents: 28171
diff changeset
1325 \lineiii{\var{a}.pop(\var{k}\optional{, \var{x}})}
92e3b611dc9f SF patch #693753: fix for bug 639806: default for dict.pop
Raymond Hettinger <python@rcn.com>
parents: 28171
diff changeset
1326 {\code{\var{a}[\var{k}]} if \code{\var{k} in \var{a}},
92e3b611dc9f SF patch #693753: fix for bug 639806: default for dict.pop
Raymond Hettinger <python@rcn.com>
parents: 28171
diff changeset
1327 else \var{x} (and remove k)}
92e3b611dc9f SF patch #693753: fix for bug 639806: default for dict.pop
Raymond Hettinger <python@rcn.com>
parents: 28171
diff changeset
1328 {(8)}
15522
aaa54752e4ba "Documentation" for {}.popitem().
Guido van Rossum <guido@python.org>
parents: 15463
diff changeset
1329 \lineiii{\var{a}.popitem()}
aaa54752e4ba "Documentation" for {}.popitem().
Guido van Rossum <guido@python.org>
parents: 15463
diff changeset
1330 {remove and return an arbitrary (\var{key}, \var{value}) pair}
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1331 {(6)}
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1332 \lineiii{\var{a}.iteritems()}
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1333 {return an iterator over (\var{key}, \var{value}) pairs}
24902
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1334 {(2), (3)}
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1335 \lineiii{\var{a}.iterkeys()}
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1336 {return an iterator over the mapping's keys}
24902
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1337 {(2), (3)}
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1338 \lineiii{\var{a}.itervalues()}
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1339 {return an iterator over the mapping's values}
24902
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1340 {(2), (3)}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1341 \end{tableiii}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1342
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1343 \noindent
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1344 Notes:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1345 \begin{description}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1346 \item[(1)] Raises a \exception{KeyError} exception if \var{k} is not
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1347 in the map.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1348
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1349 \item[(2)] \versionadded{2.2}
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1350
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1351 \item[(3)] Keys and values are listed in random order. If
24902
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1352 \method{items()}, \method{keys()}, \method{values()},
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1353 \method{iteritems()}, \method{iterkeys()}, and \method{itervalues()}
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1354 are called with no intervening modifications to the dictionary, the
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1355 lists will directly correspond. This allows the creation of
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1356 \code{(\var{value}, \var{key})} pairs using \function{zip()}:
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1357 \samp{pairs = zip(\var{a}.values(), \var{a}.keys())}. The same
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1358 relationship holds for the \method{iterkeys()} and
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1359 \method{itervalues()} methods: \samp{pairs = zip(\var{a}.itervalues(),
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1360 \var{a}.iterkeys())} provides the same value for \code{pairs}.
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1361 Another way to create the same list is \samp{pairs = [(v, k) for (k,
f57d6db423f2 Extend some comments on the order of values in the returns from
Fred Drake <fdrake@acm.org>
parents: 24631
diff changeset
1362 v) in \var{a}.iteritems()]}.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1363
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1364 \item[(4)] Never raises an exception if \var{k} is not in the map,
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
1365 instead it returns \var{x}. \var{x} is optional; when \var{x} is not
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1366 provided and \var{k} is not in the map, \code{None} is returned.
13894
77b9e041b595 Barry's patch to document the new setdefault() method. Slightly
Guido van Rossum <guido@python.org>
parents: 13780
diff changeset
1367
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1368 \item[(5)] \function{setdefault()} is like \function{get()}, except
13894
77b9e041b595 Barry's patch to document the new setdefault() method. Slightly
Guido van Rossum <guido@python.org>
parents: 13780
diff changeset
1369 that if \var{k} is missing, \var{x} is both returned and inserted into
77b9e041b595 Barry's patch to document the new setdefault() method. Slightly
Guido van Rossum <guido@python.org>
parents: 13780
diff changeset
1370 the dictionary as the value of \var{k}.
15522
aaa54752e4ba "Documentation" for {}.popitem().
Guido van Rossum <guido@python.org>
parents: 15463
diff changeset
1371
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1372 \item[(6)] \function{popitem()} is useful to destructively iterate
15522
aaa54752e4ba "Documentation" for {}.popitem().
Guido van Rossum <guido@python.org>
parents: 15463
diff changeset
1373 over a dictionary, as often used in set algorithms.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1374
26437
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1375 \item[(7)] \function{fromkeys()} is a class method that returns a
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1376 new dictionary. \var{value} defaults to \code{None}. \versionadded{2.3}
28211
92e3b611dc9f SF patch #693753: fix for bug 639806: default for dict.pop
Raymond Hettinger <python@rcn.com>
parents: 28171
diff changeset
1377
92e3b611dc9f SF patch #693753: fix for bug 639806: default for dict.pop
Raymond Hettinger <python@rcn.com>
parents: 28171
diff changeset
1378 \item[(8)] \function{pop()} raises a \exception{KeyError} when no default
92e3b611dc9f SF patch #693753: fix for bug 639806: default for dict.pop
Raymond Hettinger <python@rcn.com>
parents: 28171
diff changeset
1379 value is given and the key is not found. \versionadded{2.3}
26437
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1380
31616
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1381 \item[(9)] \function{update()} accepts either another mapping object
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1382 or an iterable of key/value pairs (as a tuple or other iterable of
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1383 length two). If keyword arguments are specified, the mapping is
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1384 then is updated with those key/value pairs:
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1385 \samp{d.update(red=1, blue=2)}.
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1386 \versionchanged[Allowed the argument to be an iterable of key/value
5b3898d9ba59 SF #904720: dict.update should take a 2-tuple sequence like dict.__init_
Raymond Hettinger <python@rcn.com>
parents: 31357
diff changeset
1387 pairs and allowed keyword arguments]{2.4}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1388
31631
228d264c5fbb SF Patch #912462: Relocate \end tag to the right place.
Hye-Shik Chang <hyeshik@gmail.com>
parents: 31616
diff changeset
1389 \end{description}
228d264c5fbb SF Patch #912462: Relocate \end tag to the right place.
Hye-Shik Chang <hyeshik@gmail.com>
parents: 31616
diff changeset
1390
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1391 \subsection{File Objects
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1392 \label{bltin-file-objects}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1393
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1394 File objects\obindex{file} are implemented using C's \code{stdio}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1395 package and can be created with the built-in constructor
22241
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
1396 \function{file()}\bifuncindex{file} described in section
20764
37b8d92e12f5 Mention the new file() builtin in the section on file objects.
Tim Peters <tim.peters@gmail.com>
parents: 20701
diff changeset
1397 \ref{built-in-funcs}, ``Built-in Functions.''\footnote{\function{file()}
37b8d92e12f5 Mention the new file() builtin in the section on file objects.
Tim Peters <tim.peters@gmail.com>
parents: 20701
diff changeset
1398 is new in Python 2.2. The older built-in \function{open()} is an
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1399 alias for \function{file()}.} File objects are also returned
18416
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make
Fred Drake <fdrake@acm.org>
parents: 18395
diff changeset
1400 by some other built-in functions and methods, such as
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
1401 \function{os.popen()} and \function{os.fdopen()} and the
9461
9ffd604807c2 Don't describe something as "below"; that won't make sense for the
Fred Drake <fdrake@acm.org>
parents: 9318
diff changeset
1402 \method{makefile()} method of socket objects.
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
1403 \refstmodindex{os}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1404 \refbimodindex{socket}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1405
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1406 When a file operation fails for an I/O-related reason, the exception
9558
fa867d8ee7eb Remove some remaining {\rm ...} constructs.
Fred Drake <fdrake@acm.org>
parents: 9523
diff changeset
1407 \exception{IOError} is raised. This includes situations where the
fa867d8ee7eb Remove some remaining {\rm ...} constructs.
Fred Drake <fdrake@acm.org>
parents: 9523
diff changeset
1408 operation is not defined for some reason, like \method{seek()} on a tty
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1409 device or writing a file opened for reading.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1410
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1411 Files have the following methods:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1412
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1413
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1414 \begin{methoddesc}[file]{close}{}
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1415 Close the file. A closed file cannot be read or written any more.
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1416 Any operation which requires that the file be open will raise a
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1417 \exception{ValueError} after the file has been closed. Calling
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1418 \method{close()} more than once is allowed.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1419 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1420
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1421 \begin{methoddesc}[file]{flush}{}
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1422 Flush the internal buffer, like \code{stdio}'s
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1423 \cfunction{fflush()}. This may be a no-op on some file-like
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1424 objects.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1425 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1426
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1427 \begin{methoddesc}[file]{fileno}{}
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1428 \index{file descriptor}
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1429 \index{descriptor, file}
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1430 Return the integer ``file descriptor'' that is used by the
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1431 underlying implementation to request I/O operations from the
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1432 operating system. This can be useful for other, lower level
18416
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make
Fred Drake <fdrake@acm.org>
parents: 18395
diff changeset
1433 interfaces that use file descriptors, such as the
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make
Fred Drake <fdrake@acm.org>
parents: 18395
diff changeset
1434 \refmodule{fcntl}\refbimodindex{fcntl} module or
20580
376ee174ecd0 Use the \note and \warning macros where appropriate.
Fred Drake <fdrake@acm.org>
parents: 20173
diff changeset
1435 \function{os.read()} and friends. \note{File-like objects
18416
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make
Fred Drake <fdrake@acm.org>
parents: 18395
diff changeset
1436 which do not have a real file descriptor should \emph{not} provide
20580
376ee174ecd0 Use the \note and \warning macros where appropriate.
Fred Drake <fdrake@acm.org>
parents: 20173
diff changeset
1437 this method!}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1438 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1439
24599
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1440 \begin{methoddesc}[file]{isatty}{}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1441 Return \code{True} if the file is connected to a tty(-like) device, else
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1442 \code{False}. \note{If a file-like object is not associated
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1443 with a real file, this method should \emph{not} be implemented.}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1444 \end{methoddesc}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1445
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1446 \begin{methoddesc}[file]{next}{}
30413
53f1c32ee69d SF bug #804280: fromkeys is not listed in index
Raymond Hettinger <python@rcn.com>
parents: 30375
diff changeset
1447 A file object is its own iterator, for example \code{iter(\var{f})} returns
24599
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1448 \var{f} (unless \var{f} is closed). When a file is used as an
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1449 iterator, typically in a \keyword{for} loop (for example,
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1450 \code{for line in f: print line}), the \method{next()} method is
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1451 called repeatedly. This method returns the next input line, or raises
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1452 \exception{StopIteration} when \EOF{} is hit. In order to make a
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1453 \keyword{for} loop the most efficient way of looping over the lines of
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1454 a file (a very common operation), the \method{next()} method uses a
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1455 hidden read-ahead buffer. As a consequence of using a read-ahead
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1456 buffer, combining \method{next()} with other file methods (like
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1457 \method{readline()}) does not work right. However, using
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1458 \method{seek()} to reposition the file to an absolute position will
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1459 flush the read-ahead buffer.
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1460 \versionadded{2.3}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1461 \end{methoddesc}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1462
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1463 \begin{methoddesc}[file]{read}{\optional{size}}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1464 Read at most \var{size} bytes from the file (less if the read hits
10606
fe5fcb7e73f7 Correct documentation for <file>.read(); Python makes a serious
Fred Drake <fdrake@acm.org>
parents: 10520
diff changeset
1465 \EOF{} before obtaining \var{size} bytes). If the \var{size}
fe5fcb7e73f7 Correct documentation for <file>.read(); Python makes a serious
Fred Drake <fdrake@acm.org>
parents: 10520
diff changeset
1466 argument is negative or omitted, read all data until \EOF{} is
fe5fcb7e73f7 Correct documentation for <file>.read(); Python makes a serious
Fred Drake <fdrake@acm.org>
parents: 10520
diff changeset
1467 reached. The bytes are returned as a string object. An empty
fe5fcb7e73f7 Correct documentation for <file>.read(); Python makes a serious
Fred Drake <fdrake@acm.org>
parents: 10520
diff changeset
1468 string is returned when \EOF{} is encountered immediately. (For
fe5fcb7e73f7 Correct documentation for <file>.read(); Python makes a serious
Fred Drake <fdrake@acm.org>
parents: 10520
diff changeset
1469 certain files, like ttys, it makes sense to continue reading after
fe5fcb7e73f7 Correct documentation for <file>.read(); Python makes a serious
Fred Drake <fdrake@acm.org>
parents: 10520
diff changeset
1470 an \EOF{} is hit.) Note that this method may call the underlying
fe5fcb7e73f7 Correct documentation for <file>.read(); Python makes a serious
Fred Drake <fdrake@acm.org>
parents: 10520
diff changeset
1471 C function \cfunction{fread()} more than once in an effort to
26672
8dd25a6f5913 Fixed bug
Gustavo Niemeyer <gustavo@niemeyer.net>
parents: 26592
diff changeset
1472 acquire as close to \var{size} bytes as possible. Also note that
8dd25a6f5913 Fixed bug
Gustavo Niemeyer <gustavo@niemeyer.net>
parents: 26592
diff changeset
1473 when in non-blocking mode, less data than what was requested may
8dd25a6f5913 Fixed bug
Gustavo Niemeyer <gustavo@niemeyer.net>
parents: 26592
diff changeset
1474 be returned, even if no \var{size} parameter was given.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1475 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1476
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1477 \begin{methoddesc}[file]{readline}{\optional{size}}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1478 Read one entire line from the file. A trailing newline character is
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1479 kept in the string (but may be absent when a file ends with an
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1480 incomplete line).\footnote{
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1481 The advantage of leaving the newline on is that
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1482 returning an empty string is then an unambiguous \EOF{}
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1483 indication. It is also possible (in cases where it might
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1484 matter, for example, if you
22241
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
1485 want to make an exact copy of a file while scanning its lines)
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1486 to tell whether the last line of a file ended in a newline
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
1487 or not (yes this happens!).
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1488 } If the \var{size} argument is present and
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1489 non-negative, it is a maximum byte count (including the trailing
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1490 newline) and an incomplete line may be returned.
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1491 An empty string is returned \emph{only} when \EOF{} is encountered
20580
376ee174ecd0 Use the \note and \warning macros where appropriate.
Fred Drake <fdrake@acm.org>
parents: 20173
diff changeset
1492 immediately. \note{Unlike \code{stdio}'s \cfunction{fgets()}, the
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1493 returned string contains null characters (\code{'\e 0'}) if they
20580
376ee174ecd0 Use the \note and \warning macros where appropriate.
Fred Drake <fdrake@acm.org>
parents: 20173
diff changeset
1494 occurred in the input.}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1495 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1496
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1497 \begin{methoddesc}[file]{readlines}{\optional{sizehint}}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1498 Read until \EOF{} using \method{readline()} and return a list containing
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1499 the lines thus read. If the optional \var{sizehint} argument is
21062
bc02c3b09626 Clean up some markup cruft. A number of the macros that take no
Fred Drake <fdrake@acm.org>
parents: 20767
diff changeset
1500 present, instead of reading up to \EOF, whole lines totalling
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1501 approximately \var{sizehint} bytes (possibly after rounding up to an
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1502 internal buffer size) are read. Objects implementing a file-like
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1503 interface may choose to ignore \var{sizehint} if it cannot be
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1504 implemented, or cannot be implemented efficiently.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1505 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1506
15926
ac13cef423c8 Document xreadlines() method. (Forgot to check this in before!)
Guido van Rossum <guido@python.org>
parents: 15896
diff changeset
1507 \begin{methoddesc}[file]{xreadlines}{}
24599
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1508 This method returns the same thing as \code{iter(f)}.
17612
c19d6db6e99b Only document <file>.xreadlines() once; added version annotation.
Fred Drake <fdrake@acm.org>
parents: 17603
diff changeset
1509 \versionadded{2.1}
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1510 \deprecated{2.3}{Use \samp{for \var{line} in \var{file}} instead.}
15926
ac13cef423c8 Document xreadlines() method. (Forgot to check this in before!)
Guido van Rossum <guido@python.org>
parents: 15896
diff changeset
1511 \end{methoddesc}
ac13cef423c8 Document xreadlines() method. (Forgot to check this in before!)
Guido van Rossum <guido@python.org>
parents: 15896
diff changeset
1512
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1513 \begin{methoddesc}[file]{seek}{offset\optional{, whence}}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1514 Set the file's current position, like \code{stdio}'s \cfunction{fseek()}.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1515 The \var{whence} argument is optional and defaults to \code{0}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1516 (absolute file positioning); other values are \code{1} (seek
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1517 relative to the current position) and \code{2} (seek relative to the
15731
a06415994cb5 Added information about the interaction of opening a file in append mode
Fred Drake <fdrake@acm.org>
parents: 15522
diff changeset
1518 file's end). There is no return value. Note that if the file is
a06415994cb5 Added information about the interaction of opening a file in append mode
Fred Drake <fdrake@acm.org>
parents: 15522
diff changeset
1519 opened for appending (mode \code{'a'} or \code{'a+'}), any
a06415994cb5 Added information about the interaction of opening a file in append mode
Fred Drake <fdrake@acm.org>
parents: 15522
diff changeset
1520 \method{seek()} operations will be undone at the next write. If the
a06415994cb5 Added information about the interaction of opening a file in append mode
Fred Drake <fdrake@acm.org>
parents: 15522
diff changeset
1521 file is only opened for writing in append mode (mode \code{'a'}),
a06415994cb5 Added information about the interaction of opening a file in append mode
Fred Drake <fdrake@acm.org>
parents: 15522
diff changeset
1522 this method is essentially a no-op, but it remains useful for files
30705
3ff03446f362 Patch #809535: Mention behaviour of seek on text files. Backported to 2.3.
Martin v. Löwis <martin@v.loewis.de>
parents: 30697
diff changeset
1523 opened in append mode with reading enabled (mode \code{'a+'}). If the
3ff03446f362 Patch #809535: Mention behaviour of seek on text files. Backported to 2.3.
Martin v. Löwis <martin@v.loewis.de>
parents: 30697
diff changeset
1524 file is opened in text mode (mode \code{'t'}), only offsets returned
3ff03446f362 Patch #809535: Mention behaviour of seek on text files. Backported to 2.3.
Martin v. Löwis <martin@v.loewis.de>
parents: 30697
diff changeset
1525 by \method{tell()} are legal. Use of other offsets causes undefined
3ff03446f362 Patch #809535: Mention behaviour of seek on text files. Backported to 2.3.
Martin v. Löwis <martin@v.loewis.de>
parents: 30697
diff changeset
1526 behavior.
3ff03446f362 Patch #809535: Mention behaviour of seek on text files. Backported to 2.3.
Martin v. Löwis <martin@v.loewis.de>
parents: 30697
diff changeset
1527
3ff03446f362 Patch #809535: Mention behaviour of seek on text files. Backported to 2.3.
Martin v. Löwis <martin@v.loewis.de>
parents: 30697
diff changeset
1528 Note that not all file objects are seekable.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1529 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1530
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1531 \begin{methoddesc}[file]{tell}{}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1532 Return the file's current position, like \code{stdio}'s
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1533 \cfunction{ftell()}.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1534 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1535
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1536 \begin{methoddesc}[file]{truncate}{\optional{size}}
22241
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
1537 Truncate the file's size. If the optional \var{size} argument is
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1538 present, the file is truncated to (at most) that size. The size
22241
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
1539 defaults to the current position. The current file position is
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
1540 not changed. Note that if a specified size exceeds the file's
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
1541 current size, the result is platform-dependent: possibilities
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
1542 include that file may remain unchanged, increase to the specified
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
1543 size as if zero-filled, or increase to the specified size with
7584b6f1afde Change Windows file.truncate() to (a) restore the original file position,
Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
1544 undefined new content.
30375
4aa84a8b1fe4 Fix spacing markup and other sundries.
Raymond Hettinger <python@rcn.com>
parents: 30250
diff changeset
1545 Availability: Windows, many \UNIX{} variants.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1546 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1547
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1548 \begin{methoddesc}[file]{write}{str}
20580
376ee174ecd0 Use the \note and \warning macros where appropriate.
Fred Drake <fdrake@acm.org>
parents: 20173
diff changeset
1549 Write a string to the file. There is no return value. Due to
15789
9e9556924b0a Added documentation for the xreadlines module & related changes. The
Fred Drake <fdrake@acm.org>
parents: 15731
diff changeset
1550 buffering, the string may not actually show up in the file until
9e9556924b0a Added documentation for the xreadlines module & related changes. The
Fred Drake <fdrake@acm.org>
parents: 15731
diff changeset
1551 the \method{flush()} or \method{close()} method is called.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1552 \end{methoddesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1553
20045
7b8c11739714 Generalize file.writelines() to allow iterable objects.
Tim Peters <tim.peters@gmail.com>
parents: 20031
diff changeset
1554 \begin{methoddesc}[file]{writelines}{sequence}
7b8c11739714 Generalize file.writelines() to allow iterable objects.
Tim Peters <tim.peters@gmail.com>
parents: 20031
diff changeset
1555 Write a sequence of strings to the file. The sequence can be any
7b8c11739714 Generalize file.writelines() to allow iterable objects.
Tim Peters <tim.peters@gmail.com>
parents: 20031
diff changeset
1556 iterable object producing strings, typically a list of strings.
7b8c11739714 Generalize file.writelines() to allow iterable objects.
Tim Peters <tim.peters@gmail.com>
parents: 20031
diff changeset
1557 There is no return value.
15789
9e9556924b0a Added documentation for the xreadlines module & related changes. The
Fred Drake <fdrake@acm.org>
parents: 15731
diff changeset
1558 (The name is intended to match \method{readlines()};
9e9556924b0a Added documentation for the xreadlines module & related changes. The
Fred Drake <fdrake@acm.org>
parents: 15731
diff changeset
1559 \method{writelines()} does not add line separators.)
9e9556924b0a Added documentation for the xreadlines module & related changes. The
Fred Drake <fdrake@acm.org>
parents: 15731
diff changeset
1560 \end{methoddesc}
9e9556924b0a Added documentation for the xreadlines module & related changes. The
Fred Drake <fdrake@acm.org>
parents: 15731
diff changeset
1561
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1562
20031
e5a3f9d7766b Note that files are iterable; describe what the iterator returns.
Fred Drake <fdrake@acm.org>
parents: 19529
diff changeset
1563 Files support the iterator protocol. Each iteration returns the same
e5a3f9d7766b Note that files are iterable; describe what the iterator returns.
Fred Drake <fdrake@acm.org>
parents: 19529
diff changeset
1564 result as \code{\var{file}.readline()}, and iteration ends when the
e5a3f9d7766b Note that files are iterable; describe what the iterator returns.
Fred Drake <fdrake@acm.org>
parents: 19529
diff changeset
1565 \method{readline()} method returns an empty string.
e5a3f9d7766b Note that files are iterable; describe what the iterator returns.
Fred Drake <fdrake@acm.org>
parents: 19529
diff changeset
1566
e5a3f9d7766b Note that files are iterable; describe what the iterator returns.
Fred Drake <fdrake@acm.org>
parents: 19529
diff changeset
1567
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1568 File objects also offer a number of other interesting attributes.
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1569 These are not required for file-like objects, but should be
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1570 implemented if they make sense for the particular object.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1571
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1572 \begin{memberdesc}[file]{closed}
22920
2392af05f052 Update docs for bool changes by Guido around April 6
Neal Norwitz <nnorwitz@gmail.com>
parents: 22785
diff changeset
1573 bool indicating the current state of the file object. This is a
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1574 read-only attribute; the \method{close()} method changes the value.
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1575 It may not be available on all file-like objects.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1576 \end{memberdesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1577
29065
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1578 \begin{memberdesc}[file]{encoding}
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1579 The encoding that this file uses. When Unicode strings are written
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1580 to a file, they will be converted to byte strings using this encoding.
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1581 In addition, when the file is connected to a terminal, the attribute
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1582 gives the encoding that the terminal is likely to use (that
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1583 information might be incorrect if the user has misconfigured the
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1584 terminal). The attribute is read-only and may not be present on
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1585 all file-like objects. It may also be \code{None}, in which case
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1586 the file uses the system default encoding for converting Unicode
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1587 strings.
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1588
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1589 \versionadded{2.3}
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1590 \end{memberdesc}
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1591
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1592 \begin{memberdesc}[file]{mode}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1593 The I/O mode for the file. If the file was created using the
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1594 \function{open()} built-in function, this will be the value of the
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1595 \var{mode} parameter. This is a read-only attribute and may not be
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1596 present on all file-like objects.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1597 \end{memberdesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1598
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1599 \begin{memberdesc}[file]{name}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1600 If the file object was created using \function{open()}, the name of
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1601 the file. Otherwise, some string that indicates the source of the
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1602 file object, of the form \samp{<\mbox{\ldots}>}. This is a read-only
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1603 attribute and may not be present on all file-like objects.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1604 \end{memberdesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1605
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1606 \begin{memberdesc}[file]{newlines}
31282
8b62f4194a7e markup fix
Fred Drake <fdrake@acm.org>
parents: 31210
diff changeset
1607 If Python was built with the \longprogramopt{with-universal-newlines}
8b62f4194a7e markup fix
Fred Drake <fdrake@acm.org>
parents: 31210
diff changeset
1608 option to \program{configure} (the default) this read-only attribute
8b62f4194a7e markup fix
Fred Drake <fdrake@acm.org>
parents: 31210
diff changeset
1609 exists, and for files opened in
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1610 universal newline read mode it keeps track of the types of newlines
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1611 encountered while reading the file. The values it can take are
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1612 \code{'\e r'}, \code{'\e n'}, \code{'\e r\e n'}, \code{None} (unknown,
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1613 no newlines read yet) or a tuple containing all the newline
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1614 types seen, to indicate that multiple
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1615 newline conventions were encountered. For files not opened in universal
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1616 newline read mode the value of this attribute will be \code{None}.
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1617 \end{memberdesc}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1618
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1619 \begin{memberdesc}[file]{softspace}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1620 Boolean that indicates whether a space character needs to be printed
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1621 before another value when using the \keyword{print} statement.
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1622 Classes that are trying to simulate a file object should also have a
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1623 writable \member{softspace} attribute, which should be initialized to
14485
ac0246586d52 Improve a couple of references to the language reference, making them
Fred Drake <fdrake@acm.org>
parents: 14044
diff changeset
1624 zero. This will be automatic for most classes implemented in Python
ac0246586d52 Improve a couple of references to the language reference, making them
Fred Drake <fdrake@acm.org>
parents: 14044
diff changeset
1625 (care may be needed for objects that override attribute access); types
ac0246586d52 Improve a couple of references to the language reference, making them
Fred Drake <fdrake@acm.org>
parents: 14044
diff changeset
1626 implemented in C will have to provide a writable
ac0246586d52 Improve a couple of references to the language reference, making them
Fred Drake <fdrake@acm.org>
parents: 14044
diff changeset
1627 \member{softspace} attribute.
20580
376ee174ecd0 Use the \note and \warning macros where appropriate.
Fred Drake <fdrake@acm.org>
parents: 20173
diff changeset
1628 \note{This attribute is not used to control the
14705
4712f5b8f279 Clarify that the softspace attribute is used by print for state management,
Fred Drake <fdrake@acm.org>
parents: 14685
diff changeset
1629 \keyword{print} statement, but to allow the implementation of
20580
376ee174ecd0 Use the \note and \warning macros where appropriate.
Fred Drake <fdrake@acm.org>
parents: 20173
diff changeset
1630 \keyword{print} to keep track of its internal state.}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1631 \end{memberdesc}
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1632
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1633
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1634 \subsection{Other Built-in Types \label{typesother}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1635
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1636 The interpreter supports several other kinds of objects.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1637 Most of these support only one or two operations.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1638
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1639
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1640 \subsubsection{Modules \label{typesmodules}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1641
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1642 The only special operation on a module is attribute access:
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1643 \code{\var{m}.\var{name}}, where \var{m} is a module and \var{name}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1644 accesses a name defined in \var{m}'s symbol table. Module attributes
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1645 can be assigned to. (Note that the \keyword{import} statement is not,
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1646 strictly speaking, an operation on a module object; \code{import
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1647 \var{foo}} does not require a module object named \var{foo} to exist,
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1648 rather it requires an (external) \emph{definition} for a module named
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1649 \var{foo} somewhere.)
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1650
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1651 A special member of every module is \member{__dict__}.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1652 This is the dictionary containing the module's symbol table.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1653 Modifying this dictionary will actually change the module's symbol
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1654 table, but direct assignment to the \member{__dict__} attribute is not
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1655 possible (you can write \code{\var{m}.__dict__['a'] = 1}, which
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1656 defines \code{\var{m}.a} to be \code{1}, but you can't write
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1657 \code{\var{m}.__dict__ = \{\}}). Modifying \member{__dict__} directly
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1658 is not recommended.
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1659
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1660 Modules built into the interpreter are written like this:
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1661 \code{<module 'sys' (built-in)>}. If loaded from a file, they are
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1662 written as \code{<module 'os' from
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1663 '/usr/local/lib/python\shortversion/os.pyc'>}.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1664
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1665
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1666 \subsubsection{Classes and Class Instances \label{typesobjects}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1667 \nodename{Classes and Instances}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1668
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1669 See chapters 3 and 7 of the \citetitle[../ref/ref.html]{Python
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1670 Reference Manual} for these.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1671
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1672
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1673 \subsubsection{Functions \label{typesfunctions}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1674
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1675 Function objects are created by function definitions. The only
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1676 operation on a function object is to call it:
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1677 \code{\var{func}(\var{argument-list})}.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1678
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1679 There are really two flavors of function objects: built-in functions
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1680 and user-defined functions. Both support the same operation (to call
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1681 the function), but the implementation is different, hence the
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1682 different object types.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1683
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1684 The implementation adds two special read-only attributes:
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1685 \code{\var{f}.func_code} is a function's \dfn{code
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1686 object}\obindex{code} (see below) and \code{\var{f}.func_globals} is
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1687 the dictionary used as the function's global namespace (this is the
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1688 same as \code{\var{m}.__dict__} where \var{m} is the module in which
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1689 the function \var{f} was defined).
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1690
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1691 Function objects also support getting and setting arbitrary
30413
53f1c32ee69d SF bug #804280: fromkeys is not listed in index
Raymond Hettinger <python@rcn.com>
parents: 30375
diff changeset
1692 attributes, which can be used, for example, to attach metadata to
53f1c32ee69d SF bug #804280: fromkeys is not listed in index
Raymond Hettinger <python@rcn.com>
parents: 30375
diff changeset
1693 functions. Regular attribute dot-notation is used to get and set such
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1694 attributes. \emph{Note that the current implementation only supports
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1695 function attributes on user-defined functions. Function attributes on
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1696 built-in functions may be supported in the future.}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1697
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1698 Functions have another special attribute \code{\var{f}.__dict__}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1699 (a.k.a. \code{\var{f}.func_dict}) which contains the namespace used to
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1700 support function attributes. \code{__dict__} and \code{func_dict} can
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1701 be accessed directly or set to a dictionary object. A function's
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1702 dictionary cannot be deleted.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1703
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1704 \subsubsection{Methods \label{typesmethods}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1705 \obindex{method}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1706
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1707 Methods are functions that are called using the attribute notation.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1708 There are two flavors: built-in methods (such as \method{append()} on
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1709 lists) and class instance methods. Built-in methods are described
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1710 with the types that support them.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1711
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1712 The implementation adds two special read-only attributes to class
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1713 instance methods: \code{\var{m}.im_self} is the object on which the
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1714 method operates, and \code{\var{m}.im_func} is the function
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1715 implementing the method. Calling \code{\var{m}(\var{arg-1},
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1716 \var{arg-2}, \textrm{\ldots}, \var{arg-n})} is completely equivalent to
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1717 calling \code{\var{m}.im_func(\var{m}.im_self, \var{arg-1},
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1718 \var{arg-2}, \textrm{\ldots}, \var{arg-n})}.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1719
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1720 Class instance methods are either \emph{bound} or \emph{unbound},
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1721 referring to whether the method was accessed through an instance or a
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1722 class, respectively. When a method is unbound, its \code{im_self}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1723 attribute will be \code{None} and if called, an explicit \code{self}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1724 object must be passed as the first argument. In this case,
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1725 \code{self} must be an instance of the unbound method's class (or a
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1726 subclass of that class), otherwise a \code{TypeError} is raised.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1727
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1728 Like function objects, methods objects support getting
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1729 arbitrary attributes. However, since method attributes are actually
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1730 stored on the underlying function object (\code{meth.im_func}),
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1731 setting method attributes on either bound or unbound methods is
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1732 disallowed. Attempting to set a method attribute results in a
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1733 \code{TypeError} being raised. In order to set a method attribute,
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1734 you need to explicitly set it on the underlying function object:
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1735
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1736 \begin{verbatim}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1737 class C:
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1738 def method(self):
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1739 pass
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1740
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1741 c = C()
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1742 c.method.im_func.whoami = 'my name is c'
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1743 \end{verbatim}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1744
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1745 See the \citetitle[../ref/ref.html]{Python Reference Manual} for more
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1746 information.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1747
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1748
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1749 \subsubsection{Code Objects \label{bltin-code-objects}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1750 \obindex{code}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1751
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1752 Code objects are used by the implementation to represent
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1753 ``pseudo-compiled'' executable Python code such as a function body.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1754 They differ from function objects because they don't contain a
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1755 reference to their global execution environment. Code objects are
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1756 returned by the built-in \function{compile()} function and can be
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1757 extracted from function objects through their \member{func_code}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1758 attribute.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1759 \bifuncindex{compile}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1760 \withsubitem{(function object attribute)}{\ttindex{func_code}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1761
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1762 A code object can be executed or evaluated by passing it (instead of a
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1763 source string) to the \keyword{exec} statement or the built-in
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1764 \function{eval()} function.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1765 \stindex{exec}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1766 \bifuncindex{eval}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1768 See the \citetitle[../ref/ref.html]{Python Reference Manual} for more
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1769 information.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1770
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1771
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1772 \subsubsection{Type Objects \label{bltin-type-objects}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1773
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1774 Type objects represent the various object types. An object's type is
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1775 accessed by the built-in function \function{type()}. There are no special
31286
3894654b4848 fix a variety of markup bugs
Fred Drake <fdrake@acm.org>
parents: 31282
diff changeset
1776 operations on types. The standard module \refmodule{types} defines names
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1777 for all standard built-in types.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1778 \bifuncindex{type}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1779 \refstmodindex{types}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1780
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1781 Types are written like this: \code{<type 'int'>}.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1782
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1783
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1784 \subsubsection{The Null Object \label{bltin-null-object}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1785
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1786 This object is returned by functions that don't explicitly return a
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1787 value. It supports no special operations. There is exactly one null
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1788 object, named \code{None} (a built-in name).
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1789
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1790 It is written as \code{None}.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1791
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1792
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1793 \subsubsection{The Ellipsis Object \label{bltin-ellipsis-object}}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1794
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1795 This object is used by extended slice notation (see the
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1796 \citetitle[../ref/ref.html]{Python Reference Manual}). It supports no
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1797 special operations. There is exactly one ellipsis object, named
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1798 \constant{Ellipsis} (a built-in name).
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1799
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1800 It is written as \code{Ellipsis}.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1801
22785
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1802 \subsubsection{Boolean Values}
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1803
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1804 Boolean values are the two constant objects \code{False} and
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1805 \code{True}. They are used to represent truth values (although other
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1806 values can also be considered false or true). In numeric contexts
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1807 (for example when used as the argument to an arithmetic operator),
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1808 they behave like the integers 0 and 1, respectively. The built-in
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1809 function \function{bool()} can be used to cast any value to a Boolean,
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1810 if the value can be interpreted as a truth value (see section Truth
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1811 Value Testing above).
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1812
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1813 They are written as \code{False} and \code{True}, respectively.
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1814 \index{False}
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1815 \index{True}
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1816 \indexii{Boolean}{values}
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1817
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1818
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1819 \subsubsection{Internal Objects \label{typesinternal}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1820
11463
17e12305973e Use \citetitle and \programopt as appropriate.
Fred Drake <fdrake@acm.org>
parents: 11183
diff changeset
1821 See the \citetitle[../ref/ref.html]{Python Reference Manual} for this
14044
a905c5aa0691 As pointed out by Denis S. Otkidach <den@analyt.chem.msu.ru>, xrange()
Fred Drake <fdrake@acm.org>
parents: 13967
diff changeset
1822 information. It describes stack frame objects, traceback objects, and
a905c5aa0691 As pointed out by Denis S. Otkidach <den@analyt.chem.msu.ru>, xrange()
Fred Drake <fdrake@acm.org>
parents: 13967
diff changeset
1823 slice objects.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1824
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1825
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
1826 \subsection{Special Attributes \label{specialattrs}}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1827
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1828 The implementation adds a few special read-only attributes to several
32070
b319db3869d8 add note about the __name__ read-only attribute
Fred Drake <fdrake@acm.org>
parents: 31631
diff changeset
1829 object types, where they are relevant. Some of these are not reported
b319db3869d8 add note about the __name__ read-only attribute
Fred Drake <fdrake@acm.org>
parents: 31631
diff changeset
1830 by the \function{dir()} built-in function.
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1831
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1832 \begin{memberdesc}[object]{__dict__}
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1833 A dictionary or other mapping object used to store an
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
1834 object's (writable) attributes.
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1835 \end{memberdesc}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1836
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1837 \begin{memberdesc}[object]{__methods__}
21159
6fa96b329e15 Remove most references to __members__ and __methods__, leaving only one pair
Fred Drake <fdrake@acm.org>
parents: 21062
diff changeset
1838 \deprecated{2.2}{Use the built-in function \function{dir()} to get a
6fa96b329e15 Remove most references to __members__ and __methods__, leaving only one pair
Fred Drake <fdrake@acm.org>
parents: 21062
diff changeset
1839 list of an object's attributes. This attribute is no longer available.}
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1840 \end{memberdesc}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1841
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1842 \begin{memberdesc}[object]{__members__}
21159
6fa96b329e15 Remove most references to __members__ and __methods__, leaving only one pair
Fred Drake <fdrake@acm.org>
parents: 21062
diff changeset
1843 \deprecated{2.2}{Use the built-in function \function{dir()} to get a
6fa96b329e15 Remove most references to __members__ and __methods__, leaving only one pair
Fred Drake <fdrake@acm.org>
parents: 21062
diff changeset
1844 list of an object's attributes. This attribute is no longer available.}
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1845 \end{memberdesc}
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1846
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1847 \begin{memberdesc}[instance]{__class__}
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1848 The class to which a class instance belongs.
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1849 \end{memberdesc}
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1850
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1851 \begin{memberdesc}[class]{__bases__}
18416
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make
Fred Drake <fdrake@acm.org>
parents: 18395
diff changeset
1852 The tuple of base classes of a class object. If there are no base
33b4357aebb8 Fix up a few style nits -- avoid "e.g." and "i.e." -- these make
Fred Drake <fdrake@acm.org>
parents: 18395
diff changeset
1853 classes, this will be an empty tuple.
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1854 \end{memberdesc}
32070
b319db3869d8 add note about the __name__ read-only attribute
Fred Drake <fdrake@acm.org>
parents: 31631
diff changeset
1855
b319db3869d8 add note about the __name__ read-only attribute
Fred Drake <fdrake@acm.org>
parents: 31631
diff changeset
1856 \begin{memberdesc}[class]{__name__}
b319db3869d8 add note about the __name__ read-only attribute
Fred Drake <fdrake@acm.org>
parents: 31631
diff changeset
1857 The name of the class or type.
b319db3869d8 add note about the __name__ read-only attribute
Fred Drake <fdrake@acm.org>
parents: 31631
diff changeset
1858 \end{memberdesc}