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Discussion of signatures for unicode.translate() and str.translate() were in the wrong file. Moved out of libstring.tex and into libstdtypes.tex.
author Raymond Hettinger <python@rcn.com>
date Wed, 16 Jul 2003 05:11:27 +0000
parents 8807e901c526
children e3c9b48de60a
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1 \section{Built-in Types \label{types}}
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2
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3 The following sections describe the standard types that are built into
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4 the interpreter. Historically, Python's built-in types have differed
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5 from user-defined types because it was not possible to use the built-in
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6 types as the basis for object-oriented inheritance. With the 2.2
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7 release this situation has started to change, although the intended
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8 unification of user-defined and built-in types is as yet far from
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9 complete.
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10
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11 The principal built-in types are numerics, sequences, mappings, files
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12 classes, instances and exceptions.
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13 \indexii{built-in}{types}
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14
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15 Some operations are supported by several object types; in particular,
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16 all objects can be compared, tested for truth value, and converted to
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17 a string (with the \code{`\textrm{\ldots}`} notation). The latter
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18 conversion is implicitly used when an object is written by the
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19 \keyword{print}\stindex{print} statement.
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20 (Information on \ulink{\keyword{print} statement}{../ref/print.html}
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21 and other language statements can be found in the
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22 \citetitle[../ref/ref.html]{Python Reference Manual} and the
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23 \citetitle[../tut/tut.html]{Python Tutorial}.)
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24
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25
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26 \subsection{Truth Value Testing\label{truth}}
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27
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28 Any object can be tested for truth value, for use in an \keyword{if} or
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29 \keyword{while} condition or as operand of the Boolean operations below.
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30 The following values are considered false:
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31 \stindex{if}
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32 \stindex{while}
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33 \indexii{truth}{value}
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34 \indexii{Boolean}{operations}
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35 \index{false}
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36
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37 \begin{itemize}
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38
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39 \item \code{None}
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40 \withsubitem{(Built-in object)}{\ttindex{None}}
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41
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42 \item \code{False}
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43 \withsubitem{(Built-in object)}{\ttindex{False}}
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44
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45 \item zero of any numeric type, for example, \code{0}, \code{0L},
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46 \code{0.0}, \code{0j}.
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47
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48 \item any empty sequence, for example, \code{''}, \code{()}, \code{[]}.
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49
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50 \item any empty mapping, for example, \code{\{\}}.
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51
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52 \item instances of user-defined classes, if the class defines a
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53 \method{__nonzero__()} or \method{__len__()} method, when that
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54 method returns the integer zero or \class{bool} value
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55 \code{False}.\footnote{Additional
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56 information on these special methods may be found in the
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57 \citetitle[../ref/ref.html]{Python Reference Manual}.}
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58
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59 \end{itemize}
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60
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61 All other values are considered true --- so objects of many types are
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62 always true.
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63 \index{true}
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64
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65 Operations and built-in functions that have a Boolean result always
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66 return \code{0} or \code{False} for false and \code{1} or \code{True}
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67 for true, unless otherwise stated. (Important exception: the Boolean
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68 operations \samp{or}\opindex{or} and \samp{and}\opindex{and} always
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69 return one of their operands.)
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70 \index{False}
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71 \index{True}
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72
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73 \subsection{Boolean Operations \label{boolean}}
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74
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75 These are the Boolean operations, ordered by ascending priority:
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76 \indexii{Boolean}{operations}
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77
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78 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
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79 \lineiii{\var{x} or \var{y}}
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80 {if \var{x} is false, then \var{y}, else \var{x}}{(1)}
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81 \lineiii{\var{x} and \var{y}}
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82 {if \var{x} is false, then \var{x}, else \var{y}}{(1)}
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83 \hline
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84 \lineiii{not \var{x}}
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85 {if \var{x} is false, then \code{True}, else \code{False}}{(2)}
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86 \end{tableiii}
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87 \opindex{and}
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88 \opindex{or}
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89 \opindex{not}
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90
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91 \noindent
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92 Notes:
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93
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94 \begin{description}
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95
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96 \item[(1)]
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97 These only evaluate their second argument if needed for their outcome.
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98
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99 \item[(2)]
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100 \samp{not} has a lower priority than non-Boolean operators, so
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101 \code{not \var{a} == \var{b}} is interpreted as \code{not (\var{a} ==
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102 \var{b})}, and \code{\var{a} == not \var{b}} is a syntax error.
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103
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104 \end{description}
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105
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106
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107 \subsection{Comparisons \label{comparisons}}
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108
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109 Comparison operations are supported by all objects. They all have the
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110 same priority (which is higher than that of the Boolean operations).
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111 Comparisons can be chained arbitrarily; for example, \code{\var{x} <
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112 \var{y} <= \var{z}} is equivalent to \code{\var{x} < \var{y} and
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113 \var{y} <= \var{z}}, except that \var{y} is evaluated only once (but
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114 in both cases \var{z} is not evaluated at all when \code{\var{x} <
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115 \var{y}} is found to be false).
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116 \indexii{chaining}{comparisons}
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117
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118 This table summarizes the comparison operations:
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119
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120 \begin{tableiii}{c|l|c}{code}{Operation}{Meaning}{Notes}
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121 \lineiii{<}{strictly less than}{}
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122 \lineiii{<=}{less than or equal}{}
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123 \lineiii{>}{strictly greater than}{}
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124 \lineiii{>=}{greater than or equal}{}
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125 \lineiii{==}{equal}{}
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126 \lineiii{!=}{not equal}{(1)}
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127 \lineiii{<>}{not equal}{(1)}
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128 \lineiii{is}{object identity}{}
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129 \lineiii{is not}{negated object identity}{}
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130 \end{tableiii}
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131 \indexii{operator}{comparison}
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132 \opindex{==} % XXX *All* others have funny characters < ! >
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133 \opindex{is}
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134 \opindex{is not}
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135
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136 \noindent
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137 Notes:
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138
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139 \begin{description}
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140
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141 \item[(1)]
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142 \code{<>} and \code{!=} are alternate spellings for the same operator.
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143 \code{!=} is the preferred spelling; \code{<>} is obsolescent.
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144
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145 \end{description}
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146
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147 Objects of different types, except different numeric types and different string types, never
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148 compare equal; such objects are ordered consistently but arbitrarily
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149 (so that sorting a heterogeneous array yields a consistent result).
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150 Furthermore, some types (for example, file objects) support only a
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151 degenerate notion of comparison where any two objects of that type are
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152 unequal. Again, such objects are ordered arbitrarily but
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153 consistently. The \code{<}, \code{<=}, \code{>} and \code{>=}
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154 operators will raise a \exception{TypeError} exception when any operand
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155 is a complex number.
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156 \indexii{object}{numeric}
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157 \indexii{objects}{comparing}
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158
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159 Instances of a class normally compare as non-equal unless the class
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160 \withsubitem{(instance method)}{\ttindex{__cmp__()}}
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161 defines the \method{__cmp__()} method. Refer to the
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162 \citetitle[../ref/customization.html]{Python Reference Manual} for
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163 information on the use of this method to effect object comparisons.
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164
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165 \strong{Implementation note:} Objects of different types except
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166 numbers are ordered by their type names; objects of the same types
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167 that don't support proper comparison are ordered by their address.
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168
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169 Two more operations with the same syntactic priority,
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170 \samp{in}\opindex{in} and \samp{not in}\opindex{not in}, are supported
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171 only by sequence types (below).
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172
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173
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174 \subsection{Numeric Types \label{typesnumeric}}
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175
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176 There are four distinct numeric types: \dfn{plain integers},
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177 \dfn{long integers},
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178 \dfn{floating point numbers}, and \dfn{complex numbers}.
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179 In addition, Booleans are a subtype of plain integers.
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180 Plain integers (also just called \dfn{integers})
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181 are implemented using \ctype{long} in C, which gives them at least 32
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182 bits of precision. Long integers have unlimited precision. Floating
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183 point numbers are implemented using \ctype{double} in C. All bets on
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184 their precision are off unless you happen to know the machine you are
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185 working with.
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186 \obindex{numeric}
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187 \obindex{Boolean}
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188 \obindex{integer}
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189 \obindex{long integer}
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190 \obindex{floating point}
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191 \obindex{complex number}
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192 \indexii{C}{language}
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193
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194 Complex numbers have a real and imaginary part, which are each
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195 implemented using \ctype{double} in C. To extract these parts from
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196 a complex number \var{z}, use \code{\var{z}.real} and \code{\var{z}.imag}.
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197
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198 Numbers are created by numeric literals or as the result of built-in
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199 functions and operators. Unadorned integer literals (including hex
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200 and octal numbers) yield plain integers unless the value they denote
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201 is too large to be represented as a plain integer, in which case
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202 they yield a long integer. Integer literals with an
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203 \character{L} or \character{l} suffix yield long integers
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204 (\character{L} is preferred because \samp{1l} looks too much like
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205 eleven!). Numeric literals containing a decimal point or an exponent
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206 sign yield floating point numbers. Appending \character{j} or
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207 \character{J} to a numeric literal yields a complex number with a
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208 zero real part. A complex numeric literal is the sum of a real and
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209 an imaginary part.
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210 \indexii{numeric}{literals}
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211 \indexii{integer}{literals}
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212 \indexiii{long}{integer}{literals}
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213 \indexii{floating point}{literals}
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214 \indexii{complex number}{literals}
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215 \indexii{hexadecimal}{literals}
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216 \indexii{octal}{literals}
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217
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218 Python fully supports mixed arithmetic: when a binary arithmetic
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219 operator has operands of different numeric types, the operand with the
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220 ``narrower'' type is widened to that of the other, where plain
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221 integer is narrower than long integer is narrower than floating point is
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222 narrower than complex.
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223 Comparisons between numbers of mixed type use the same rule.\footnote{
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224 As a consequence, the list \code{[1, 2]} is considered equal
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225 to \code{[1.0, 2.0]}, and similarly for tuples.
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226 } The constructors \function{int()}, \function{long()}, \function{float()},
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227 and \function{complex()} can be used
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228 to produce numbers of a specific type.
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229 \index{arithmetic}
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230 \bifuncindex{int}
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231 \bifuncindex{long}
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232 \bifuncindex{float}
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233 \bifuncindex{complex}
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234
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235 All numeric types (except complex) support the following operations,
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236 sorted by ascending priority (operations in the same box have the same
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237 priority; all numeric operations have a higher priority than
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238 comparison operations):
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239
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240 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
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241 \lineiii{\var{x} + \var{y}}{sum of \var{x} and \var{y}}{}
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242 \lineiii{\var{x} - \var{y}}{difference of \var{x} and \var{y}}{}
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243 \hline
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244 \lineiii{\var{x} * \var{y}}{product of \var{x} and \var{y}}{}
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245 \lineiii{\var{x} / \var{y}}{quotient of \var{x} and \var{y}}{(1)}
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246 \lineiii{\var{x} \%{} \var{y}}{remainder of \code{\var{x} / \var{y}}}{(4)}
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247 \hline
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248 \lineiii{-\var{x}}{\var{x} negated}{}
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249 \lineiii{+\var{x}}{\var{x} unchanged}{}
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250 \hline
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251 \lineiii{abs(\var{x})}{absolute value or magnitude of \var{x}}{}
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252 \lineiii{int(\var{x})}{\var{x} converted to integer}{(2)}
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253 \lineiii{long(\var{x})}{\var{x} converted to long integer}{(2)}
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254 \lineiii{float(\var{x})}{\var{x} converted to floating point}{}
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255 \lineiii{complex(\var{re},\var{im})}{a complex number with real part \var{re}, imaginary part \var{im}. \var{im} defaults to zero.}{}
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256 \lineiii{\var{c}.conjugate()}{conjugate of the complex number \var{c}}{}
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257 \lineiii{divmod(\var{x}, \var{y})}{the pair \code{(\var{x} / \var{y}, \var{x} \%{} \var{y})}}{(3)(4)}
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258 \lineiii{pow(\var{x}, \var{y})}{\var{x} to the power \var{y}}{}
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259 \lineiii{\var{x} ** \var{y}}{\var{x} to the power \var{y}}{}
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260 \end{tableiii}
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261 \indexiii{operations on}{numeric}{types}
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262 \withsubitem{(complex number method)}{\ttindex{conjugate()}}
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263
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264 \noindent
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265 Notes:
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266 \begin{description}
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267
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268 \item[(1)]
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269 For (plain or long) integer division, the result is an integer.
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270 The result is always rounded towards minus infinity: 1/2 is 0,
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271 (-1)/2 is -1, 1/(-2) is -1, and (-1)/(-2) is 0. Note that the result
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272 is a long integer if either operand is a long integer, regardless of
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273 the numeric value.
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274 \indexii{integer}{division}
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275 \indexiii{long}{integer}{division}
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276
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277 \item[(2)]
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278 Conversion from floating point to (long or plain) integer may round or
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279 truncate as in C; see functions \function{floor()} and
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280 \function{ceil()} in the \refmodule{math}\refbimodindex{math} module
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281 for well-defined conversions.
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282 \withsubitem{(in module math)}{\ttindex{floor()}\ttindex{ceil()}}
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283 \indexii{numeric}{conversions}
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284 \indexii{C}{language}
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285
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286 \item[(3)]
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287 See section \ref{built-in-funcs}, ``Built-in Functions,'' for a full
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288 description.
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289
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290 \item[(4)]
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291 Complex floor division operator, modulo operator, and \function{divmod()}.
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292
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293 \deprecated{2.3}{Instead convert to float using \function{abs()}
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294 if appropriate.}
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295
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296 \end{description}
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297 % XXXJH exceptions: overflow (when? what operations?) zerodivision
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298
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299 \subsubsection{Bit-string Operations on Integer Types \label{bitstring-ops}}
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300 \nodename{Bit-string Operations}
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301
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302 Plain and long integer types support additional operations that make
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303 sense only for bit-strings. Negative numbers are treated as their 2's
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304 complement value (for long integers, this assumes a sufficiently large
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305 number of bits that no overflow occurs during the operation).
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306
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307 The priorities of the binary bit-wise operations are all lower than
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308 the numeric operations and higher than the comparisons; the unary
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309 operation \samp{\~} has the same priority as the other unary numeric
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310 operations (\samp{+} and \samp{-}).
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311
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312 This table lists the bit-string operations sorted in ascending
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313 priority (operations in the same box have the same priority):
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314
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315 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
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316 \lineiii{\var{x} | \var{y}}{bitwise \dfn{or} of \var{x} and \var{y}}{}
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317 \lineiii{\var{x} \^{} \var{y}}{bitwise \dfn{exclusive or} of \var{x} and \var{y}}{}
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318 \lineiii{\var{x} \&{} \var{y}}{bitwise \dfn{and} of \var{x} and \var{y}}{}
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319 \lineiii{\var{x} << \var{n}}{\var{x} shifted left by \var{n} bits}{(1), (2)}
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320 \lineiii{\var{x} >> \var{n}}{\var{x} shifted right by \var{n} bits}{(1), (3)}
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321 \hline
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322 \lineiii{\~\var{x}}{the bits of \var{x} inverted}{}
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323 \end{tableiii}
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324 \indexiii{operations on}{integer}{types}
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325 \indexii{bit-string}{operations}
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326 \indexii{shifting}{operations}
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327 \indexii{masking}{operations}
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328
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329 \noindent
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330 Notes:
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331 \begin{description}
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332 \item[(1)] Negative shift counts are illegal and cause a
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333 \exception{ValueError} to be raised.
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334 \item[(2)] A left shift by \var{n} bits is equivalent to
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335 multiplication by \code{pow(2, \var{n})} without overflow check.
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336 \item[(3)] A right shift by \var{n} bits is equivalent to
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337 division by \code{pow(2, \var{n})} without overflow check.
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338 \end{description}
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339
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340
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341 \subsection{Iterator Types \label{typeiter}}
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342
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343 \versionadded{2.2}
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344 \index{iterator protocol}
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345 \index{protocol!iterator}
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346 \index{sequence!iteration}
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347 \index{container!iteration over}
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348
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349 Python supports a concept of iteration over containers. This is
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350 implemented using two distinct methods; these are used to allow
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351 user-defined classes to support iteration. Sequences, described below
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352 in more detail, always support the iteration methods.
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353
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354 One method needs to be defined for container objects to provide
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355 iteration support:
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356
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357 \begin{methoddesc}[container]{__iter__}{}
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358 Return an iterator object. The object is required to support the
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359 iterator protocol described below. If a container supports
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360 different types of iteration, additional methods can be provided to
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361 specifically request iterators for those iteration types. (An
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362 example of an object supporting multiple forms of iteration would be
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363 a tree structure which supports both breadth-first and depth-first
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364 traversal.) This method corresponds to the \member{tp_iter} slot of
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365 the type structure for Python objects in the Python/C API.
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366 \end{methoddesc}
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367
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368 The iterator objects themselves are required to support the following
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369 two methods, which together form the \dfn{iterator protocol}:
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370
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371 \begin{methoddesc}[iterator]{__iter__}{}
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372 Return the iterator object itself. This is required to allow both
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373 containers and iterators to be used with the \keyword{for} and
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374 \keyword{in} statements. This method corresponds to the
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375 \member{tp_iter} slot of the type structure for Python objects in
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376 the Python/C API.
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377 \end{methoddesc}
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378
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379 \begin{methoddesc}[iterator]{next}{}
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380 Return the next item from the container. If there are no further
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381 items, raise the \exception{StopIteration} exception. This method
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382 corresponds to the \member{tp_iternext} slot of the type structure
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383 for Python objects in the Python/C API.
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384 \end{methoddesc}
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385
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386 Python defines several iterator objects to support iteration over
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387 general and specific sequence types, dictionaries, and other more
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388 specialized forms. The specific types are not important beyond their
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389 implementation of the iterator protocol.
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390
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391 The intention of the protocol is that once an iterator's
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392 \method{next()} method raises \exception{StopIteration}, it will
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393 continue to do so on subsequent calls. Implementations that
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394 do not obey this property are deemed broken. (This constraint
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395 was added in Python 2.3; in Python 2.2, various iterators are
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396 broken according to this rule.)
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397
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398 Python's generators provide a convenient way to implement the
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399 iterator protocol. If a container object's \method{__iter__()}
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400 method is implemented as a generator, it will automatically
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401 return an iterator object (technically, a generator object)
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402 supplying the \method{__iter__()} and \method{next()} methods.
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Raymond Hettinger <python@rcn.com>
parents: 29516
diff changeset
403
17658
d6498b1ef50d Added section describing the iterator protocol.
Fred Drake <fdrake@acm.org>
parents: 17616
diff changeset
404
9083
bc41e86c938c Markup nits.
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parents: 9034
diff changeset
405 \subsection{Sequence Types \label{typesseq}}
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406
13967
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
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parents: 13933
diff changeset
407 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
408 tuples, buffers, and xrange objects.
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409
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parents: 23847
diff changeset
410 String literals are written in single or double quotes:
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Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
411 \code{'xyzzy'}, \code{"frobozz"}. See chapter 2 of the
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Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
412 \citetitle[../ref/strings.html]{Python Reference Manual} for more about
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
413 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
414 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
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415 \code{u'abc'}, \code{u"def"}. Lists are constructed with square brackets,
11463
17e12305973e Use \citetitle and \programopt as appropriate.
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parents: 11183
diff changeset
416 separating items with commas: \code{[a, b, c]}. Tuples are
17e12305973e Use \citetitle and \programopt as appropriate.
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diff changeset
417 constructed by the comma operator (not within square brackets), with
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Fred Drake <fdrake@acm.org>
parents: 11183
diff changeset
418 or without enclosing parentheses, but an empty tuple must have the
17e12305973e Use \citetitle and \programopt as appropriate.
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parents: 11183
diff changeset
419 enclosing parentheses, e.g., \code{a, b, c} or \code{()}. A single
18395
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
420 item tuple must have a trailing comma, e.g., \code{(d,)}.
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421 \obindex{sequence}
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422 \obindex{string}
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423 \obindex{Unicode}
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424 \obindex{tuple}
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425 \obindex{list}
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Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
426
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
427 Buffer objects are not directly supported by Python syntax, but can be
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
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diff changeset
428 created by calling the builtin function
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parents: 24902
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429 \function{buffer()}.\bifuncindex{buffer} They don't support
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Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
430 concatenation or repetition.
18395
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parents: 18391
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431 \obindex{buffer}
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Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
432
1d0d3e6a3201 List constraints on xrange() objects.
Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
433 Xrange objects are similar to buffers in that there is no specific
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parents: 23847
diff changeset
434 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
435 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
436 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
437 \function{min()} or \function{max()} on them is inefficient.
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parents: 14710
diff changeset
438 \obindex{xrange}
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439
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Guido van Rossum <guido@python.org>
parents: 18391
diff changeset
440 Most sequence types support the following operations. The \samp{in} and
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441 \samp{not in} operations have the same priorities as the comparison
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diff changeset
442 operations. The \samp{+} and \samp{*} operations have the same
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diff changeset
443 priority as the corresponding numeric operations.\footnote{They must
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parents:
diff changeset
444 have since the parser can't tell the type of the operands.}
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445
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diff changeset
446 This table lists the sequence operations sorted in ascending priority
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diff changeset
447 (operations in the same box have the same priority). In the table,
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diff changeset
448 \var{s} and \var{t} are sequences of the same type; \var{n}, \var{i}
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449 and \var{j} are integers:
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450
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451 \begin{tableiii}{c|l|c}{code}{Operation}{Result}{Notes}
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parents: 24459
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452 \lineiii{\var{x} in \var{s}}{\code{1} if an item of \var{s} is equal to \var{x}, else \code{0}}{(1)}
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453 \lineiii{\var{x} not in \var{s}}{\code{0} if an item of \var{s} is
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454 equal to \var{x}, else \code{1}}{(1)}
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455 \hline
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456 \lineiii{\var{s} + \var{t}}{the concatenation of \var{s} and \var{t}}{}
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457 \lineiii{\var{s} * \var{n}\textrm{,} \var{n} * \var{s}}{\var{n} shallow copies of \var{s} concatenated}{(2)}
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458 \hline
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parents: 24459
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459 \lineiii{\var{s}[\var{i}]}{\var{i}'th item of \var{s}, origin 0}{(3)}
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parents: 24459
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460 \lineiii{\var{s}[\var{i}:\var{j}]}{slice of \var{s} from \var{i} to \var{j}}{(3), (4)}
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Michael W. Hudson <mwh@python.net>
parents: 27919
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461 \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)}
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462 \hline
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463 \lineiii{len(\var{s})}{length of \var{s}}{}
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464 \lineiii{min(\var{s})}{smallest item of \var{s}}{}
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465 \lineiii{max(\var{s})}{largest item of \var{s}}{}
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466 \end{tableiii}
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467 \indexiii{operations on}{sequence}{types}
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diff changeset
468 \bifuncindex{len}
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diff changeset
469 \bifuncindex{min}
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diff changeset
470 \bifuncindex{max}
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471 \indexii{concatenation}{operation}
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472 \indexii{repetition}{operation}
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473 \indexii{subscript}{operation}
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474 \indexii{slice}{operation}
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475 \indexii{extended slice}{operation}
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diff changeset
476 \opindex{in}
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477 \opindex{not in}
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478
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479 \noindent
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480 Notes:
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481
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diff changeset
482 \begin{description}
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483 \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
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parents: 24459
diff changeset
484 \code{in} and \code{not in} operations act like a substring test. In
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Barry Warsaw <barry@python.org>
parents: 24459
diff changeset
485 Python versions before 2.3, \var{x} had to be a string of length 1.
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parents: 24459
diff changeset
486 In Python 2.3 and beyond, \var{x} may be a string of any length.
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parents: 24459
diff changeset
487
12e146171f3d Committing patch #591250 which provides "str1 in str2" when str1 is a
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parents: 24459
diff changeset
488 \item[(2)] Values of \var{n} less than \code{0} are treated as
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Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
489 \code{0} (which yields an empty sequence of the same type as
19529
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parents: 19243
diff changeset
490 \var{s}). Note also that the copies are shallow; nested structures
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parents: 19243
diff changeset
491 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
492
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
493 \begin{verbatim}
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
494 >>> lists = [[]] * 3
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
495 >>> lists
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
496 [[], [], []]
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
497 >>> lists[0].append(3)
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
498 >>> lists
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
499 [[3], [3], [3]]
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
500 \end{verbatim}
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
501
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
502 What has happened is that \code{lists} is a list containing three
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parents: 19243
diff changeset
503 copies of the list \code{[[]]} (a one-element list containing an
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
504 empty list), but the contained list is shared by each copy. You can
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diff changeset
505 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
506
dd8d6153a8c6 Added explanation that [...] * n generates shallow copies of [...], so
Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
507 \begin{verbatim}
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
508 >>> lists = [[] for i in range(3)]
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
509 >>> lists[0].append(3)
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
510 >>> lists[1].append(5)
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
511 >>> lists[2].append(7)
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Fred Drake <fdrake@acm.org>
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diff changeset
512 >>> lists
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Fred Drake <fdrake@acm.org>
parents: 19243
diff changeset
513 [[3], [5], [7]]
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parents: 19243
diff changeset
514 \end{verbatim}
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diff changeset
515
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diff changeset
516 \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
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parents: 18395
diff changeset
517 the end of the string: \code{len(\var{s}) + \var{i}} or
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518 \code{len(\var{s}) + \var{j}} is substituted. But note that \code{-0} is
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diff changeset
519 still \code{0}.
22241
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Tim Peters <tim.peters@gmail.com>
parents: 22214
diff changeset
520
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diff changeset
521 \item[(4)] The slice of \var{s} from \var{i} to \var{j} is defined as
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diff changeset
522 the sequence of items with index \var{k} such that \code{\var{i} <=
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diff changeset
523 \var{k} < \var{j}}. If \var{i} or \var{j} is greater than
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diff changeset
524 \code{len(\var{s})}, use \code{len(\var{s})}. If \var{i} is omitted,
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diff changeset
525 use \code{0}. If \var{j} is omitted, use \code{len(\var{s})}. If
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parents:
diff changeset
526 \var{i} is greater than or equal to \var{j}, the slice is empty.
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Michael W. Hudson <mwh@python.net>
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diff changeset
527
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
528 \item[(5)] The slice of \var{s} from \var{i} to \var{j} with step
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529 \var{k} is defined as the sequence of items with index
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diff changeset
530 \code{\var{x} = \var{i} + \var{n}*\var{k}} such that \code{0}
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diff changeset
531 \code{<=} \var{n} \code{<} \code{abs(i-j)}. If \var{i} or \var{j}
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532 is greater than \code{len(\var{s})}, use \code{len(\var{s})}. If
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diff changeset
533 \var{i} or \var{j} are ommitted then they become ``end'' values
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534 (which end depends on the sign of \var{k}).
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diff changeset
535
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
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diff changeset
536 \end{description}
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diff changeset
537
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
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diff changeset
538
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
539 \subsubsection{String Methods \label{string-methods}}
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diff changeset
540
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
541 These are the string methods which both 8-bit strings and Unicode
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
542 objects support:
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
543
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
544 \begin{methoddesc}[string]{capitalize}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
545 Return a copy of the string with only its first character capitalized.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
546 \end{methoddesc}
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diff changeset
547
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
548 \begin{methoddesc}[string]{center}{width}
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parents: 13894
diff changeset
549 Return centered in a string of length \var{width}. Padding is done
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
550 using spaces.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
551 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
552
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
553 \begin{methoddesc}[string]{count}{sub\optional{, start\optional{, end}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
554 Return the number of occurrences of substring \var{sub} in string
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diff changeset
555 S\code{[\var{start}:\var{end}]}. Optional arguments \var{start} and
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diff changeset
556 \var{end} are interpreted as in slice notation.
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diff changeset
557 \end{methoddesc}
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diff changeset
558
21332
fbbd8a4ca7a6 Added documentation for str.decode().
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diff changeset
559 \begin{methoddesc}[string]{decode}{\optional{encoding\optional{, errors}}}
fbbd8a4ca7a6 Added documentation for str.decode().
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parents: 21177
diff changeset
560 Decodes the string using the codec registered for \var{encoding}.
fbbd8a4ca7a6 Added documentation for str.decode().
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diff changeset
561 \var{encoding} defaults to the default string encoding. \var{errors}
fbbd8a4ca7a6 Added documentation for str.decode().
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diff changeset
562 may be given to set a different error handling scheme. The default is
fbbd8a4ca7a6 Added documentation for str.decode().
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diff changeset
563 \code{'strict'}, meaning that encoding errors raise
fbbd8a4ca7a6 Added documentation for str.decode().
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parents: 21177
diff changeset
564 \exception{ValueError}. Other possible values are \code{'ignore'} and
fbbd8a4ca7a6 Added documentation for str.decode().
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parents: 21177
diff changeset
565 \code{replace'}.
fbbd8a4ca7a6 Added documentation for str.decode().
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diff changeset
566 \versionadded{2.2}
fbbd8a4ca7a6 Added documentation for str.decode().
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parents: 21177
diff changeset
567 \end{methoddesc}
fbbd8a4ca7a6 Added documentation for str.decode().
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parents: 21177
diff changeset
568
13933
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diff changeset
569 \begin{methoddesc}[string]{encode}{\optional{encoding\optional{,errors}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
570 Return an encoded version of the string. Default encoding is the current
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diff changeset
571 default string encoding. \var{errors} may be given to set a different
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
572 error handling scheme. The default for \var{errors} is
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diff changeset
573 \code{'strict'}, meaning that encoding errors raise a
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
574 \exception{ValueError}. Other possible values are \code{'ignore'} and
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
575 \code{'replace'}.
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12aec3381c94 Marc-Andre Lemburg <mal@lemburg.com> noted that the encode() string method
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parents: 15005
diff changeset
576 \versionadded{2.0}
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
577 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
578
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
579 \begin{methoddesc}[string]{endswith}{suffix\optional{, start\optional{, end}}}
28171
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diff changeset
580 Return \code{True} if the string ends with the specified \var{suffix},
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diff changeset
581 otherwise return \code{False}. With optional \var{start}, test beginning at
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
582 that position. With optional \var{end}, stop comparing at that position.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
583 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
584
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
585 \begin{methoddesc}[string]{expandtabs}{\optional{tabsize}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
586 Return a copy of the string where all tab characters are expanded
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
587 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
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diff changeset
588 characters is assumed.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
589 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
590
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
591 \begin{methoddesc}[string]{find}{sub\optional{, start\optional{, end}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
592 Return the lowest index in the string where substring \var{sub} is
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
593 found, such that \var{sub} is contained in the range [\var{start},
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
594 \var{end}). Optional arguments \var{start} and \var{end} are
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
595 interpreted as in slice notation. Return \code{-1} if \var{sub} is
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
596 not found.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
597 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
598
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
599 \begin{methoddesc}[string]{index}{sub\optional{, start\optional{, end}}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
600 Like \method{find()}, but raise \exception{ValueError} when the
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diff changeset
601 substring is not found.
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diff changeset
602 \end{methoddesc}
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diff changeset
603
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
604 \begin{methoddesc}[string]{isalnum}{}
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parents: 13894
diff changeset
605 Return true if all characters in the string are alphanumeric and there
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
606 is at least one character, false otherwise.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
607 \end{methoddesc}
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parents: 13894
diff changeset
608
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
609 \begin{methoddesc}[string]{isalpha}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
610 Return true if all characters in the string are alphabetic and there
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
611 is at least one character, false otherwise.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
612 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
613
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
614 \begin{methoddesc}[string]{isdigit}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
615 Return true if there are only digit characters, false otherwise.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
616 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
617
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
618 \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
619 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
620 there is at least one cased character, false otherwise.
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]{isspace}{}
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 there are only whitespace characters in the string and
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
625 the string is not empty, false otherwise.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
626 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
627
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
628 \begin{methoddesc}[string]{istitle}{}
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
629 Return true if the string is a titlecased string: uppercase
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
630 characters may only follow uncased characters and lowercase characters
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
631 only cased ones. Return false otherwise.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
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diff changeset
632 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
633
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
634 \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
635 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
636 there is at least one cased character, false otherwise.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
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diff changeset
637 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
638
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
639 \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
640 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
641 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
642 providing this method.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
643 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
644
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
645 \begin{methoddesc}[string]{ljust}{width}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
646 Return the string left justified in a string of length \var{width}.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
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diff changeset
647 Padding is done using spaces. The original string is returned if
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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parents: 13894
diff changeset
648 \var{width} is less than \code{len(\var{s})}.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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diff changeset
649 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
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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]{lower}{}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
652 Return a copy of the string converted to lowercase.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
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diff changeset
653 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
654
23017
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
655 \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
656 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
657 \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
658 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
659 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
660 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
661 \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
662 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
663
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
664 \begin{methoddesc}[string]{replace}{old, new\optional{, maxsplit}}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
665 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
666 \var{old} replaced by \var{new}. If the optional argument
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
667 \var{maxsplit} is given, only the first \var{maxsplit} occurrences are
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
668 replaced.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
669 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
670
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
671 \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
672 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
673 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
674 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
675 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
676 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
677
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
678 \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
679 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
680 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
681 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
682
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
683 \begin{methoddesc}[string]{rjust}{width}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
684 Return the string right justified in a string of length \var{width}.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
685 Padding is done using spaces. The original string is returned if
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
686 \var{width} is less than \code{len(\var{s})}.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
687 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
688
23017
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
689 \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
690 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
691 \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
692 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
693 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
694 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
695 \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
696 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
697
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
698 \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
699 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
700 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
701 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
702 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
703 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
704
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
705 \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
706 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
707 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
708 \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
709 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
710
23017
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
711 \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
712 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
713 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
714 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
715 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
716 position.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
717 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
718
23017
44637bd7f59b Document the optional argument to the .strip(), .rstrip(), .strip() string
Fred Drake <fdrake@acm.org>
parents: 22994
diff changeset
719 \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
720 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
721 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
722 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
723 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
724 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
725 \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
726 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
727
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
728 \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
729 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
730 lowercase and vice versa.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
731 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
732
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
733 \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
734 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
735 characters, all remaining cased characters are lowercase.
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
736 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
737
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
738 \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
739 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
740 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
741 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
742 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
743
e9dddfd2a62f Discussion of signatures for unicode.translate() and str.translate()
Raymond Hettinger <python@rcn.com>
parents: 29590
diff changeset
744 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
745 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
746 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
747 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
748 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
749 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
750 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
751 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
752 \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
753 \end{methoddesc}
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
754
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
755 \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
756 Return a copy of the string converted to uppercase.
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
23045
8b1268bc371a Apply the second version of SF patch http://www.python.org/sf/536241
Walter Dörwald <walter@livinglogic.de>
parents: 23017
diff changeset
759 \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
760 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
761 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
762 \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
763 \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
764 \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
765
13933
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
766
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
767 \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
768
21177
7d1eac41ce3e Slightly improved indexing for the string-% operator, thanks to comments
Fred Drake <fdrake@acm.org>
parents: 21163
diff changeset
769 \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
770 \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
771 \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
772 \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
773 \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
774 \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
775 \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
776 \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
777
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
778 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
779 \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
780 \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
781 \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
782 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
783 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
784 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
785 \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
786 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
787 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
788
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
789 If \var{format} requires a single argument, \var{values} may be a
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
790 single non-tuple object. \footnote{To format only a tuple you
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
791 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
792 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
793 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
794 single mapping object (for example, a dictionary).
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
795
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
796 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
797 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
798
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
799 \begin{enumerate}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
800 \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
801 specifier.
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
802 \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
803 of characters (for example, \code{(somename)}).
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
804 \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
805 conversion types.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
806 \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
807 \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
808 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
809 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
810 precision.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
811 \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
812 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
813 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
814 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
815 the precision.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
816 \item Length modifier (optional).
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
817 \item Conversion type.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
818 \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
819
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
820 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
821 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
822 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
823 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
824 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
825
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
826 \begin{verbatim}
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
827 >>> 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
828 {'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
829 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
830 \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
831
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
832 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
833 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
834
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
835 The conversion flag characters are:
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
836
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
837 \begin{tableii}{c|l}{character}{Flag}{Meaning}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
838 \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
839 (where defined below).}
27919
4b5c2e025c5e Fix SF bug #687655, String formatting conversions misleading
Neal Norwitz <nnorwitz@gmail.com>
parents: 27225
diff changeset
840 \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
841 \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
842 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
843 \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
844 (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
845 \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
846 precede the conversion (overrides a "space" flag).}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
847 \end{tableii}
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
848
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
849 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
850 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
851
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
852 The conversion types are:
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
853
25906
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
854 \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
855 \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
856 \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
857 \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
858 \lineiii{u}{Unsigned decimal.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
859 \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
860 \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
861 \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
862 \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
863 \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
864 \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
865 \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
866 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
867 \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
868 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
869 \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
870 string).}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
871 \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
872 \function{repr()}).}{(3)}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
873 \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
874 \function{str()}).}{(4)}
25906
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
875 \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
876 character in the result.}{}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
877 \end{tableiii}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
878
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
879 \noindent
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
880 Notes:
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
881 \begin{description}
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
882 \item[(1)]
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
883 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
884 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
885 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
886 zero.
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
887 \item[(2)]
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
888 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
889 (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
890 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
891 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
892 not already a zero.
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
893 \item[(3)]
50905db35da5 - The "-" format flag overrides the "0" flag, not the "-" flag.
Fred Drake <fdrake@acm.org>
parents: 25393
diff changeset
894 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
895 \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
896 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
897 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
898 \end{description}
16285
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
899
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
900 % XXX Examples?
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
901
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
902 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
903 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
904
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
905 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
906 \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
907 are replaced by \code{\%g} conversions.\footnote{
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
908 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
909 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
910 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
911 point values on a particular machine.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
912 } All other errors raise exceptions.
15e0c10092bb Massively improved documentation for string formatting operations,
Fred Drake <fdrake@acm.org>
parents: 15926
diff changeset
913
21163
7b6879714b74 Make no assumption about how modules are built when referring to them; this
Fred Drake <fdrake@acm.org>
parents: 21159
diff changeset
914 Additional string operations are defined in standard modules
7b6879714b74 Make no assumption about how modules are built when referring to them; this
Fred Drake <fdrake@acm.org>
parents: 21159
diff changeset
915 \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
916 \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
917
13967
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
918
14044
a905c5aa0691 As pointed out by Denis S. Otkidach <den@analyt.chem.msu.ru>, xrange()
Fred Drake <fdrake@acm.org>
parents: 13967
diff changeset
919 \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
920
15005
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
921 The xrange\obindex{xrange} type is an immutable sequence which is
14044
a905c5aa0691 As pointed out by Denis S. Otkidach <den@analyt.chem.msu.ru>, xrange()
Fred Drake <fdrake@acm.org>
parents: 13967
diff changeset
922 commonly used for looping. The advantage of the xrange type is that an
a905c5aa0691 As pointed out by Denis S. Otkidach <den@analyt.chem.msu.ru>, xrange()
Fred Drake <fdrake@acm.org>
parents: 13967
diff changeset
923 xrange object will always take the same amount of memory, no matter the
13967
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
924 size of the range it represents. There are no consistent performance
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
925 advantages.
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
926
26592
0c646baeec58 Update comments about the performance of xrange().
Raymond Hettinger <python@rcn.com>
parents: 26514
diff changeset
927 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
928 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
929
7b7ee58901fb Document the range type, as suggested by Denis S. Otkidach
Fred Drake <fdrake@acm.org>
parents: 13933
diff changeset
930
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
931 \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
932
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
933 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
934 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
935 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
936 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
937 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
938 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
939 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
940 \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
941 \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
942 \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
943
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
944 \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
945 \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
946 {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
947 \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
948 {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
949 \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
950 {same as \code{\var{s}[\var{i}:\var{j}] = []}}{}
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
951 \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
952 {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
953 \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
954 {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
955 \lineiii{\var{s}.append(\var{x})}
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
956 {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
957 \lineiii{\var{s}.extend(\var{x})}
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
958 {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
959 \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
960 {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
961 \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
962 {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
963 \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
964 \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
965 {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
966 \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
967 {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
968 \lineiii{\var{s}.remove(\var{x})}
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
969 {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
970 \lineiii{\var{s}.reverse()}
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
971 {reverses the items of \var{s} in place}{(7)}
27036
41f7726e3e51 Allow list sort's comparison function to explicitly be None. See SF patch
Skip Montanaro <skip@pobox.com>
parents: 26816
diff changeset
972 \lineiii{\var{s}.sort(\optional{\var{cmpfunc=None}})}
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
973 {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
974 \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
975 \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
976 \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
977 \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
978 \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
979 \indexii{slice}{assignment}
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
980 \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
981 \stindex{del}
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
982 \withsubitem{(list method)}{
11183
1e0b1967be7f In note mentioning [].remove()'s exception, tell what exception is
Fred Drake <fdrake@acm.org>
parents: 11100
diff changeset
983 \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
984 \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
985 \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
986 \noindent
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
987 Notes:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
988 \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
989 \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
990 replacing.
23778
245224d1b8c9 This is my nearly two year old patch
Michael W. Hudson <mwh@python.net>
parents: 23515
diff changeset
991
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
992 \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
993 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
994 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
995 deprecated since Python 1.4.
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
996
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
997 \item[(3)] Raises an exception when \var{x} is not a list object. The
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
998 \method{extend()} method is experimental and not supported by
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
999 mutable sequence types other than lists.
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1000
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1001 \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
1002 \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
1003 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
1004 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
1005 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
1006 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
1007
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1008 \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
1009 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
1010 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
1011 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
1012 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
1013
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1014 \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
1015 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
1016 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
1017
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1018 \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
1019 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
1020 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
1021 the sorted or reversed list.
12223
e82e82b3b9ad Merged changes from the 1.5.2p2 release.
Fred Drake <fdrake@acm.org>
parents: 11463
diff changeset
1022
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1023 \item[(8)] The \method{sort()} method takes an optional argument
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1024 specifying a comparison function of two arguments (list items) which
20173
f100793ca9af The list.sort() docs require a function that returns -1, 0 or +1. That's
Tim Peters <tim.peters@gmail.com>
parents: 20045
diff changeset
1025 should return a negative, zero or positive number depending on whether
11183
1e0b1967be7f In note mentioning [].remove()'s exception, tell what exception is
Fred Drake <fdrake@acm.org>
parents: 11100
diff changeset
1026 the first argument is considered smaller than, equal to, or larger
1e0b1967be7f In note mentioning [].remove()'s exception, tell what exception is
Fred Drake <fdrake@acm.org>
parents: 11100
diff changeset
1027 than the second argument. Note that this slows the sorting process
28337
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1028 down considerably; for example to sort a list in reverse order it is much
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1029 faster to call \method{sort()} followed by \method{reverse()}
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1030 than to use \method{sort()} with a comparison function that
27036
41f7726e3e51 Allow list sort's comparison function to explicitly be None. See SF patch
Skip Montanaro <skip@pobox.com>
parents: 26816
diff changeset
1031 reverses the ordering of the elements. Passing \constant{None} as the
41f7726e3e51 Allow list sort's comparison function to explicitly be None. See SF patch
Skip Montanaro <skip@pobox.com>
parents: 26816
diff changeset
1032 comparison function is semantically equivalent to calling
41f7726e3e51 Allow list sort's comparison function to explicitly be None. See SF patch
Skip Montanaro <skip@pobox.com>
parents: 26816
diff changeset
1033 \method{sort()} with no comparison function.
28337
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1034 \versionchanged[Support for \code{None} as an equivalent to omitting
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1035 \var{cmpfunc} was added]{2.3}
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1036
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1037 As an example of using the \var{cmpfunc} argument to the
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1038 \method{sort()} method, consider sorting a list of sequences by the
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1039 second element of that list:
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1040
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1041 \begin{verbatim}
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1042 def mycmp(a, b):
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1043 return cmp(a[1], b[1])
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1044
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1045 mylist.sort(mycmp)
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1046 \end{verbatim}
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1047
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1048 A more time-efficient approach for reasonably-sized data structures can
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1049 often be used:
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1050
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1051 \begin{verbatim}
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1052 tmplist = [(x[1], x) for x in mylist]
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1053 tmplist.sort()
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1054 mylist = [x for (key, x) in tmplist]
90f17c374f59 - added example of using a comparison function with list.sort(), and
Fred Drake <fdrake@acm.org>
parents: 28211
diff changeset
1055 \end{verbatim}
24459
189eb6fa9ded Added new footnote about list.sort() stability. Repaired footnote about
Tim Peters <tim.peters@gmail.com>
parents: 24253
diff changeset
1056
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1057 \item[(9)] Whether the \method{sort()} method is stable is not defined by
24459
189eb6fa9ded Added new footnote about list.sort() stability. Repaired footnote about
Tim Peters <tim.peters@gmail.com>
parents: 24253
diff changeset
1058 the language (a sort is stable if it guarantees not to change the
189eb6fa9ded Added new footnote about list.sort() stability. Repaired footnote about
Tim Peters <tim.peters@gmail.com>
parents: 24253
diff changeset
1059 relative order of elements that compare equal). In the C
189eb6fa9ded Added new footnote about list.sort() stability. Repaired footnote about
Tim Peters <tim.peters@gmail.com>
parents: 24253
diff changeset
1060 implementation of Python, sorts were stable only by accident through
189eb6fa9ded Added new footnote about list.sort() stability. Repaired footnote about
Tim Peters <tim.peters@gmail.com>
parents: 24253
diff changeset
1061 Python 2.2. The C implementation of Python 2.3 introduced a stable
189eb6fa9ded Added new footnote about list.sort() stability. Repaired footnote about
Tim Peters <tim.peters@gmail.com>
parents: 24253
diff changeset
1062 \method{sort()} method, but code that intends to be portable across
189eb6fa9ded Added new footnote about list.sort() stability. Repaired footnote about
Tim Peters <tim.peters@gmail.com>
parents: 24253
diff changeset
1063 implementations and versions must not rely on stability.
26161
dd10d97d329a SF patch 637176: list.sort crasher
Tim Peters <tim.peters@gmail.com>
parents: 25906
diff changeset
1064
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1065 \item[(10)] While a list is being sorted, the effect of attempting to
26161
dd10d97d329a SF patch 637176: list.sort crasher
Tim Peters <tim.peters@gmail.com>
parents: 25906
diff changeset
1066 mutate, or even inspect, the list is undefined. The C implementation
dd10d97d329a SF patch 637176: list.sort crasher
Tim Peters <tim.peters@gmail.com>
parents: 25906
diff changeset
1067 of Python 2.3 makes the list appear empty for the duration, and raises
dd10d97d329a SF patch 637176: list.sort crasher
Tim Peters <tim.peters@gmail.com>
parents: 25906
diff changeset
1068 \exception{ValueError} if it can detect that the list has been
dd10d97d329a SF patch 637176: list.sort crasher
Tim Peters <tim.peters@gmail.com>
parents: 25906
diff changeset
1069 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
1070 \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
1071
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1072
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
1073 \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
1074 \obindex{mapping}
0cf5111bf09c Use \obindex{...} instead of \indexii{...}{type} in many places; this is
Fred Drake <fdrake@acm.org>
parents: 14710
diff changeset
1075 \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
1076
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1077 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
1078 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
1079 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
1080 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
1081 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
1082 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
1083 Numeric types used for keys obey the normal rules for numeric
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1084 comparison: if two numbers compare equal (e.g. \code{1} and
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1085 \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
1086 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
1087
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1088 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
1089 \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
1090 \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
1091 \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
1092
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1093 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
1094 \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
1095 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
1096 \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
1097 \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
1098 \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
1099 \bifuncindex{len}
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1100 \withsubitem{(dictionary method)}{
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1101 \ttindex{clear()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1102 \ttindex{copy()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1103 \ttindex{has_key()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1104 \ttindex{items()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1105 \ttindex{keys()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1106 \ttindex{update()}
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1107 \ttindex{values()}
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1108 \ttindex{get()}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1109 \ttindex{setdefault()}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1110 \ttindex{pop()}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1111 \ttindex{popitem()}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1112 \ttindex{iteritems()}
29067
04065c4a1c6b Missing parenthesis found by texcheck.py
Raymond Hettinger <python@rcn.com>
parents: 29065
diff changeset
1113 \ttindex{iterkeys()}
28171
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Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1114 \ttindex{itervalues()}}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1115
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1116 \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
1117 \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
1118 \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
1119 \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
1120 {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
1121 {}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1122 \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
1123 {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
1124 {(1)}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1125 \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
1126 \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
1127 \lineiii{\var{a}.has_key(\var{k})}
17594
bf94af396b1e Implement, test and document "key in dict" and "key not in dict".
Guido van Rossum <guido@python.org>
parents: 16778
diff changeset
1128 {\code{1} if \var{a} has a key \var{k}, else \code{0}}
bf94af396b1e Implement, test and document "key in dict" and "key not in dict".
Guido van Rossum <guido@python.org>
parents: 16778
diff changeset
1129 {}
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
1130 \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
1131 {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
1132 {(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
1133 \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
1134 {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
1135 {(2)}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1136 \lineiii{\var{a}.items()}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1137 {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
1138 {(3)}
18085
7e459fb3c332 Fixed reference to table notes for {}.keys() and {}.items() -- these
Fred Drake <fdrake@acm.org>
parents: 17966
diff changeset
1139 \lineiii{\var{a}.keys()}{a copy of \var{a}'s list of keys}{(3)}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1140 \lineiii{\var{a}.update(\var{b})}
26437
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1141 {\code{for \var{k} in \var{b}.keys(): \var{a}[\var{k}] = \var{b}[\var{k}]}}
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1142 {}
26437
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1143 \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
1144 {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
1145 {(7)}
18085
7e459fb3c332 Fixed reference to table notes for {}.keys() and {}.items() -- these
Fred Drake <fdrake@acm.org>
parents: 17966
diff changeset
1146 \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
1147 \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
1148 {\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
1149 else \var{x}}
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1150 {(4)}
13894
77b9e041b595 Barry's patch to document the new setdefault() method. Slightly
Guido van Rossum <guido@python.org>
parents: 13780
diff changeset
1151 \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
1152 {\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
1153 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
1154 {(5)}
28211
92e3b611dc9f SF patch #693753: fix for bug 639806: default for dict.pop
Raymond Hettinger <python@rcn.com>
parents: 28171
diff changeset
1155 \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
1156 {\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
1157 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
1158 {(8)}
15522
aaa54752e4ba "Documentation" for {}.popitem().
Guido van Rossum <guido@python.org>
parents: 15463
diff changeset
1159 \lineiii{\var{a}.popitem()}
aaa54752e4ba "Documentation" for {}.popitem().
Guido van Rossum <guido@python.org>
parents: 15463
diff changeset
1160 {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
1161 {(6)}
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1162 \lineiii{\var{a}.iteritems()}
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1163 {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
1164 {(2), (3)}
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1165 \lineiii{\var{a}.iterkeys()}
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1166 {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
1167 {(2), (3)}
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1168 \lineiii{\var{a}.itervalues()}
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1169 {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
1170 {(2), (3)}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1171 \end{tableiii}
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1172
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1173 \noindent
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1174 Notes:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1175 \begin{description}
10968
5ba2e4ce58cb Some clarifications on operations for mapping types, based on comments
Fred Drake <fdrake@acm.org>
parents: 10785
diff changeset
1176 \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
1177 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
1178
17966
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1179 \item[(2)] \versionadded{2.2}
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1180
178bedf9536d Add descriptions of {}.iteritems(), {}.iterkeys(), and {}.itervalues()
Fred Drake <fdrake@acm.org>
parents: 17663
diff changeset
1181 \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
1182 \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
1183 \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
1184 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
1185 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
1186 \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
1187 \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
1188 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
1189 \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
1190 \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
1191 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
1192 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
1193
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1194 \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
1195 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
1196 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
1197
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1198 \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
1199 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
1200 the dictionary as the value of \var{k}.
15522
aaa54752e4ba "Documentation" for {}.popitem().
Guido van Rossum <guido@python.org>
parents: 15463
diff changeset
1201
18286
bc05a95242a3 Remove the restriction on a mapping's .update() method.
Barry Warsaw <barry@python.org>
parents: 18085
diff changeset
1202 \item[(6)] \function{popitem()} is useful to destructively iterate
15522
aaa54752e4ba "Documentation" for {}.popitem().
Guido van Rossum <guido@python.org>
parents: 15463
diff changeset
1203 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
1204
26437
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1205 \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
1206 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
1207
92e3b611dc9f SF patch #693753: fix for bug 639806: default for dict.pop
Raymond Hettinger <python@rcn.com>
parents: 28171
diff changeset
1208 \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
1209 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
1210 \end{description}
57d03375aead SF Patch 643443. Added dict.fromkeys(iterable, value=None), a class
Raymond Hettinger <python@rcn.com>
parents: 26260
diff changeset
1211
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1212
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1213 \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
1214 \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
1215
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1216 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
1217 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
1218 \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
1219 \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
1220 is new in Python 2.2. The older built-in \function{open()} is an
37b8d92e12f5 Mention the new file() builtin in the section on file objects.
Tim Peters <tim.peters@gmail.com>
parents: 20701
diff changeset
1221 alias for \function{file()}.}
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1222 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
1223 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
1224 \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
1225 \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
1226 \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
1227 \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
1228
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1229 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
1230 \exception{IOError} is raised. This includes situations where the
fa867d8ee7eb Remove some remaining {\rm ...} constructs.
Fred Drake <fdrake@acm.org>
parents: 9523
diff changeset
1231 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
1232 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
1233
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1234 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
1235
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1236
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1237 \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
1238 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
1239 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
1240 \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
1241 \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
1242 \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
1243
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1244 \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
1245 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
1246 \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
1247 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
1248 \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
1249
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1250 \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
1251 \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
1252 \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
1253 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
1254 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
1255 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
1256 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
1257 \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
1258 \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
1259 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
1260 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
1261 \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
1262
24599
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1263 \begin{methoddesc}[file]{isatty}{}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1264 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
1265 \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
1266 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
1267 \end{methoddesc}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1268
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1269 \begin{methoddesc}[file]{next}{}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1270 A file object is its own iterator, i.e. \code{iter(\var{f})} returns
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1271 \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
1272 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
1273 \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
1274 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
1275 \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
1276 \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
1277 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
1278 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
1279 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
1280 \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
1281 \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
1282 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
1283 \versionadded{2.3}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1284 \end{methoddesc}
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1285
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1286 \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
1287 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
1288 \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
1289 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
1290 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
1291 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
1292 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
1293 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
1294 C function \cfunction{fread()} more than once in an effort to
26672
8dd25a6f5913 Fixed bug
Gustavo Niemeyer <gustavo@niemeyer.net>
parents: 26592
diff changeset
1295 acquire as close to \var{size} bytes as possible. Also note that
8dd25a6f5913 Fixed bug
Gustavo Niemeyer <gustavo@niemeyer.net>
parents: 26592
diff changeset
1296 when in non-blocking mode, less data than what was requested may
8dd25a6f5913 Fixed bug
Gustavo Niemeyer <gustavo@niemeyer.net>
parents: 26592
diff changeset
1297 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
1298 \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
1299
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1300 \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
1301 Read one entire line from the file. A trailing newline character is
10520
7ee1e3134147 Fixed latex2html weirdness with footnotes.
Fred Drake <fdrake@acm.org>
parents: 10241
diff changeset
1302 kept in the string\footnote{
23860
63ee31bb25f3 Make a start at describing the results of class/type unification
Steve Holden <steve@holdenweb.com>
parents: 23847
diff changeset
1303 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
1304 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
1305 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
1306 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
1307 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
1308 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
1309 or not (yes this happens!).
4d14eef8ea07 Added Marc-Andre Lemburg's documentation for string methods, with some
Fred Drake <fdrake@acm.org>
parents: 13894
diff changeset
1310 } (but may be absent when a file ends with an
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1311 incomplete line). If the \var{size} argument is present and
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1312 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
1313 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
1314 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
1315 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
1316 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
1317 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
1318 \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
1319
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1320 \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
1321 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
1322 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
1323 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
1324 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
1325 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
1326 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
1327 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
1328 \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
1329
15926
ac13cef423c8 Document xreadlines() method. (Forgot to check this in before!)
Guido van Rossum <guido@python.org>
parents: 15896
diff changeset
1330 \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
1331 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
1332 \versionadded{2.1}
24599
d7ca0a2ce074 Document file.next(). Mark xreadlines obsolete (both method and
Guido van Rossum <guido@python.org>
parents: 24598
diff changeset
1333 \deprecated{2.3}{Use \code{for line in file} instead.}
15926
ac13cef423c8 Document xreadlines() method. (Forgot to check this in before!)
Guido van Rossum <guido@python.org>
parents: 15896
diff changeset
1334 \end{methoddesc}
ac13cef423c8 Document xreadlines() method. (Forgot to check this in before!)
Guido van Rossum <guido@python.org>
parents: 15896
diff changeset
1335
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1336 \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
1337 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
1338 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
1339 (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
1340 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
1341 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
1342 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
1343 \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
1344 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
1345 this method is essentially a no-op, but it remains useful for files
a06415994cb5 Added information about the interaction of opening a file in append mode
Fred Drake <fdrake@acm.org>
parents: 15522
diff changeset
1346 opened in append mode with reading enabled (mode \code{'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
1347 \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
1348
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1349 \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
1350 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
1351 \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
1352 \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
1353
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1354 \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
1355 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
1356 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
1357 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
1358 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
1359 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
1360 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
1361 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
1362 undefined new content.
22214
e24ba04d01b0 file_truncate(): provide full "large file" support on Windows, by
Tim Peters <tim.peters@gmail.com>
parents: 21542
diff changeset
1363 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
1364 \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
1365
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1366 \begin{methoddesc}[file]{write}{str}
20580
376ee174ecd0 Use the \note and \warning macros where appropriate.
Fred Drake <fdrake@acm.org>
parents: 20173
diff changeset
1367 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
1368 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
1369 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
1370 \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
1371
20045
7b8c11739714 Generalize file.writelines() to allow iterable objects.
Tim Peters <tim.peters@gmail.com>
parents: 20031
diff changeset
1372 \begin{methoddesc}[file]{writelines}{sequence}
7b8c11739714 Generalize file.writelines() to allow iterable objects.
Tim Peters <tim.peters@gmail.com>
parents: 20031
diff changeset
1373 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
1374 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
1375 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
1376 (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
1377 \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
1378 \end{methoddesc}
9e9556924b0a Added documentation for the xreadlines module & related changes. The
Fred Drake <fdrake@acm.org>
parents: 15731
diff changeset
1379
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1380
20031
e5a3f9d7766b Note that files are iterable; describe what the iterator returns.
Fred Drake <fdrake@acm.org>
parents: 19529
diff changeset
1381 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
1382 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
1383 \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
1384
e5a3f9d7766b Note that files are iterable; describe what the iterator returns.
Fred Drake <fdrake@acm.org>
parents: 19529
diff changeset
1385
14685
faf3e734254d Clarify a number of issues about the file-like object API based on
Fred Drake <fdrake@acm.org>
parents: 14557
diff changeset
1386 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
1387 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
1388 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
1389
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1390 \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
1391 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
1392 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
1393 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
1394 \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
1395
29065
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1396 \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
1397 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
1398 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
1399 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
1400 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
1401 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
1402 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
1403 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
1404 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
1405 strings.
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1406
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1407 \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
1408 \end{memberdesc}
bf1634b023d5 Patch #612627: Add encoding attribute to file objects, and determine
Martin v. Löwis <martin@v.loewis.de>
parents: 28909
diff changeset
1409
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1410 \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
1411 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
1412 \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
1413 \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
1414 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
1415 \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
1416
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1417 \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
1418 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
1419 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
1420 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
1421 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
1422 \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
1423
28171
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1424 \begin{memberdesc}[file]{newlines}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1425 If Python was built with the \code{--with-universal-newlines} option
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1426 (the default) this read-only attribute exists, and for files opened in
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1427 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
1428 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
1429 \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
1430 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
1431 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
1432 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
1433 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
1434 \end{memberdesc}
24fe023901b0 Back in June in revision 1.98 Steve (accidentally, presumably) wiped
Michael W. Hudson <mwh@python.net>
parents: 27919
diff changeset
1435
8730
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1436 \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
1437 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
1438 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
1439 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
1440 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
1441 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
1442 (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
1443 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
1444 \member{softspace} attribute.
20580
376ee174ecd0 Use the \note and \warning macros where appropriate.
Fred Drake <fdrake@acm.org>
parents: 20173
diff changeset
1445 \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
1446 \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
1447 \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
1448 \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
1449
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1450
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1451 \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
1452
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1453 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
1454 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
1455
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1456
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1457 \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
1458
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1459 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
1460 \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
1461 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
1462 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
1463 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
1464 \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
1465 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
1466 \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
1467
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1468 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
1469 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
1470 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
1471 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
1472 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
1473 defines \code{\var{m}.a} to be \code{1}, but you can't write
29067
04065c4a1c6b Missing parenthesis found by texcheck.py
Raymond Hettinger <python@rcn.com>
parents: 29065
diff changeset
1474 \code{\var{m}.__dict__ = \{\}}).
20767
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1475
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1476 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
1477 \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
1478 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
1479 '/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
1480
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1481
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1482 \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
1483 \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
1484
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1485 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
1486 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
1487
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1488
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1489 \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
1490
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1491 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
1492 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
1493 \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
1494
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1495 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
1496 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
1497 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
1498 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
1499
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1500 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
1501 \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
1502 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
1503 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
1504 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
1505 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
1506
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1507 Function objects also support getting and setting arbitrary
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1508 attributes, which can be used to, e.g. attach metadata to functions.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1509 Regular attribute dot-notation is used to get and set such
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1510 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
1511 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
1512 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
1513
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1514 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
1515 (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
1516 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
1517 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
1518 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
1519
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1520 \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
1521 \obindex{method}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1522
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1523 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
1524 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
1525 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
1526 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
1527
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1528 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
1529 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
1530 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
1531 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
1532 \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
1533 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
1534 \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
1535
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1536 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
1537 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
1538 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
1539 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
1540 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
1541 \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
1542 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
1543
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1544 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
1545 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
1546 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
1547 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
1548 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
1549 \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
1550 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
1551
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1552 \begin{verbatim}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1553 class C:
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1554 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
1555 pass
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1556
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1557 c = C()
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1558 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
1559 \end{verbatim}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1560
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1561 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
1562 information.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1563
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1564
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1565 \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
1566 \obindex{code}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1567
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1568 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
1569 ``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
1570 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
1571 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
1572 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
1573 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
1574 attribute.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1575 \bifuncindex{compile}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1576 \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
1577
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1578 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
1579 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
1580 \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
1581 \stindex{exec}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1582 \bifuncindex{eval}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1583
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1584 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
1585 information.
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1586
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1587
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1588 \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
1589
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1590 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
1591 accessed by the built-in function \function{type()}. There are no special
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1592 operations on types. The standard module \module{types} defines names
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1593 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
1594 \bifuncindex{type}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1595 \refstmodindex{types}
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1596
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1597 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
1598
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1599
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1600 \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
1601
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1602 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
1603 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
1604 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
1605
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1606 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
1607
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1608
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1609 \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
1610
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1611 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
1612 \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
1613 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
1614 \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
1615
b3f48c5d6e16 Promote file objects out of the "Other Objects" category, so they become
Fred Drake <fdrake@acm.org>
parents: 20764
diff changeset
1616 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
1617
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
1618 \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
1619
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1620 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
1621 \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
1622 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
1623 (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
1624 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
1625 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
1626 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
1627 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
1628
aa8d59823add Add the 'bool' type and its values 'False' and 'True', as described in
Guido van Rossum <guido@python.org>
parents: 22241
diff changeset
1629 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
1630 \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
1631 \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
1632 \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
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
10156
0f7d694bc334 Make sure all HTML pages generated from this section have reasonable
Fred Drake <fdrake@acm.org>
parents: 10147
diff changeset
1635 \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
1636
11463
17e12305973e Use \citetitle and \programopt as appropriate.
Fred Drake <fdrake@acm.org>
parents: 11183
diff changeset
1637 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
1638 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
1639 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
1640
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1641
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
1642 \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
1643
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1644 The implementation adds a few special read-only attributes to several
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1645 object types, where they are relevant:
8a306dfd9f33 Move files around to get the names to match the module names except for
Fred Drake <fdrake@acm.org>
parents:
diff changeset
1646
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1647 \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
1648 A dictionary or other mapping object used to store an
9083
bc41e86c938c Markup nits.
Fred Drake <fdrake@acm.org>
parents: 9034
diff changeset
1649 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
1650 \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
1651
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1652 \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
1653 \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
1654 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
1655 \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
1656
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1657 \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
1658 \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
1659 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
1660 \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
1661
15383
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1662 \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
1663 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
1664 \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
1665
eeb7c8a5b79f Document the proper exception to be raised by I/O operations on closed
Fred Drake <fdrake@acm.org>
parents: 15332
diff changeset
1666 \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
1667 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
1668 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
1669 \end{memberdesc}