cpython-lru_cache-weakref: Doc/tutorial/inputoutput.rst annotate

annotate Doc/tutorial/inputoutput.rst @ 74006:88198b93ff2f

Issue #13560: Add PyUnicode_EncodeLocale() * Use PyUnicode_EncodeLocale() in time.strftime() if wcsftime() is not available * Document my last changes in Misc/NEWS

author	Victor Stinner <victor.stinner@haypocalc.com>
date	Sat, 17 Dec 2011 04:13:41 +0100
parents	4a68f4cfbdc8
children	7e56c46f5707

rev	line source
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	1 .. _tut-io:
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	2
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	3 ****************
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	4 Input and Output
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	5 ****************
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	6
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	7 There are several ways to present the output of a program; data can be printed
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	8 in a human-readable form, or written to a file for future use. This chapter will
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	9 discuss some of the possibilities.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	10
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	11
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	12 .. _tut-formatting:
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	13
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	14 Fancier Output Formatting
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	15 =========================
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	16
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	17 So far we've encountered two ways of writing values: expression statements and
43115 95d6fe2e8e0e Tutorial update for 3.0 by Paul Dubois. Guido van Rossum <guido@python.org> parents: 42604 diff changeset	18 the :func:`print` function. (A third way is using the :meth:`write` method
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	19 of file objects; the standard output file can be referenced as ``sys.stdout``.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	20 See the Library Reference for more information on this.)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	21
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	22 Often you'll want more control over the formatting of your output than simply
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	23 printing space-separated values. There are two ways to format your output; the
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	24 first way is to do all the string handling yourself; using string slicing and
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	25 concatenation operations you can create any layout you can imagine. The
68285 59e464a1bbf0 #11405: do not reference the string module again for its deprecated functions, only for Template class. Georg Brandl <georg@python.org> parents: 64763 diff changeset	26 string type has some methods that perform useful operations for padding
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	27 strings to a given column width; these will be discussed shortly. The second
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	28 way is to use the :meth:`str.format` method.
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	29
68285 59e464a1bbf0 #11405: do not reference the string module again for its deprecated functions, only for Template class. Georg Brandl <georg@python.org> parents: 64763 diff changeset	30 The :mod:`string` module contains a :class:`~string.Template` class which offers
59e464a1bbf0 #11405: do not reference the string module again for its deprecated functions, only for Template class. Georg Brandl <georg@python.org> parents: 64763 diff changeset	31 yet another way to substitute values into strings.
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	32
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	33 One question remains, of course: how do you convert values to strings? Luckily,
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	34 Python has ways to convert any value to a string: pass it to the :func:`repr`
48666 fd7b93a01c04 #3523: no backquotes any more. Georg Brandl <georg@python.org> parents: 48655 diff changeset	35 or :func:`str` functions.
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	36
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	37 The :func:`str` function is meant to return representations of values which are
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	38 fairly human-readable, while :func:`repr` is meant to generate representations
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	39 which can be read by the interpreter (or will force a :exc:`SyntaxError` if
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	40 there is not equivalent syntax). For objects which don't have a particular
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	41 representation for human consumption, :func:`str` will return the same value as
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	42 :func:`repr`. Many values, such as numbers or structures like lists and
68413 4a68f4cfbdc8 Merge with 3.1. Ezio Melotti <ezio.melotti@gmail.com> parents: 68291 68411 diff changeset	43 dictionaries, have the same representation using either function. Strings, in
4a68f4cfbdc8 Merge with 3.1. Ezio Melotti <ezio.melotti@gmail.com> parents: 68291 68411 diff changeset	44 particular, have two distinct representations.
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	45
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	46 Some examples::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	47
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	48 >>> s = 'Hello, world.'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	49 >>> str(s)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	50 'Hello, world.'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	51 >>> repr(s)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	52 "'Hello, world.'"
68413 4a68f4cfbdc8 Merge with 3.1. Ezio Melotti <ezio.melotti@gmail.com> parents: 68291 68411 diff changeset	53 >>> str(1/7)
54927 e3025a4c0ad7 Merged revisions 73636 via svnmerge from Mark Dickinson <dickinsm@gmail.com> parents: 51776 diff changeset	54 '0.14285714285714285'
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	55 >>> x = 10 * 3.25
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	56 >>> y = 200 * 200
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	57 >>> s = 'The value of x is ' + repr(x) + ', and y is ' + repr(y) + '...'
43115 95d6fe2e8e0e Tutorial update for 3.0 by Paul Dubois. Guido van Rossum <guido@python.org> parents: 42604 diff changeset	58 >>> print(s)
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	59 The value of x is 32.5, and y is 40000...
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	60 >>> # The repr() of a string adds string quotes and backslashes:
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	61 ... hello = 'hello, world\n'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	62 >>> hellos = repr(hello)
43115 95d6fe2e8e0e Tutorial update for 3.0 by Paul Dubois. Guido van Rossum <guido@python.org> parents: 42604 diff changeset	63 >>> print(hellos)
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	64 'hello, world\n'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	65 >>> # The argument to repr() may be any Python object:
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	66 ... repr((x, y, ('spam', 'eggs')))
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	67 "(32.5, 40000, ('spam', 'eggs'))"
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	68
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	69 Here are two ways to write a table of squares and cubes::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	70
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	71 >>> for x in range(1, 11):
43201 4902671dd678 Tutorial formatting patch by Robin Stocker. Georg Brandl <georg@python.org> parents: 43115 diff changeset	72 ... print(repr(x).rjust(2), repr(x*x).rjust(3), end=' ')
43115 95d6fe2e8e0e Tutorial update for 3.0 by Paul Dubois. Guido van Rossum <guido@python.org> parents: 42604 diff changeset	73 ... # Note use of 'end' on previous line
95d6fe2e8e0e Tutorial update for 3.0 by Paul Dubois. Guido van Rossum <guido@python.org> parents: 42604 diff changeset	74 ... print(repr(xxx).rjust(4))
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	75 ...
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	76 1 1 1
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	77 2 4 8
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	78 3 9 27
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	79 4 16 64
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	80 5 25 125
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	81 6 36 216
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	82 7 49 343
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	83 8 64 512
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	84 9 81 729
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	85 10 100 1000
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	86
43201 4902671dd678 Tutorial formatting patch by Robin Stocker. Georg Brandl <georg@python.org> parents: 43115 diff changeset	87 >>> for x in range(1, 11):
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	88 ... print('{0:2d} {1:3d} {2:4d}'.format(x, xx, xx*x))
50563 93cf3a6ead63 Merged revisions 68226 via svnmerge from Georg Brandl <georg@python.org> parents: 48668 diff changeset	89 ...
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	90 1 1 1
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	91 2 4 8
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	92 3 9 27
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	93 4 16 64
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	94 5 25 125
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	95 6 36 216
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	96 7 49 343
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	97 8 64 512
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	98 9 81 729
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	99 10 100 1000
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	100
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	101 (Note that in the first example, one space between each column was added by the
43115 95d6fe2e8e0e Tutorial update for 3.0 by Paul Dubois. Guido van Rossum <guido@python.org> parents: 42604 diff changeset	102 way :func:`print` works: it always adds spaces between its arguments.)
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	103
68411 87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	104 This example demonstrates the :meth:`str.rjust` method of string
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	105 objects, which right-justifies a string in a field of a given width by padding
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	106 it with spaces on the left. There are similar methods :meth:`str.ljust` and
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	107 :meth:`str.center`. These methods do not write anything, they just return a
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	108 new string. If the input string is too long, they don't truncate it, but
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	109 return it unchanged; this will mess up your column lay-out but that's usually
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	110 better than the alternative, which would be lying about a value. (If you
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	111 really want truncation you can always add a slice operation, as in
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	112 ``x.ljust(n)[:n]``.)
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	113
68411 87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	114 There is another method, :meth:`str.zfill`, which pads a numeric string on the
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	115 left with zeros. It understands about plus and minus signs::
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	116
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	117 >>> '12'.zfill(5)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	118 '00012'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	119 >>> '-3.14'.zfill(7)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	120 '-003.14'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	121 >>> '3.14159265359'.zfill(5)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	122 '3.14159265359'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	123
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	124 Basic usage of the :meth:`str.format` method looks like this::
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	125
55797 afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	126 >>> print('We are the {} who say "{}!"'.format('knights', 'Ni'))
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	127 We are the knights who say "Ni!"
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	128
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	129 The brackets and characters within them (called format fields) are replaced with
68411 87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	130 the objects passed into the :meth:`str.format` method. A number in the
55797 afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	131 brackets can be used to refer to the position of the object passed into the
68411 87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	132 :meth:`str.format` method. ::
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	133
48577 71532ad7f3ed fix print syntax in tutorial Benjamin Peterson <benjamin@python.org> parents: 48563 diff changeset	134 >>> print('{0} and {1}'.format('spam', 'eggs'))
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	135 spam and eggs
48577 71532ad7f3ed fix print syntax in tutorial Benjamin Peterson <benjamin@python.org> parents: 48563 diff changeset	136 >>> print('{1} and {0}'.format('spam', 'eggs'))
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	137 eggs and spam
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	138
68411 87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	139 If keyword arguments are used in the :meth:`str.format` method, their values
55580 7b495c8f2a24 Merged revisions 73941-73943,74076,74094,74186,74211-74214,74247,74254,74262,74311,74334,74368 via svnmerge from Georg Brandl <georg@python.org> parents: 54927 diff changeset	140 are referred to by using the name of the argument. ::
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	141
48578 b8d4dbb2938a Merged revisions 65253 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 48577 diff changeset	142 >>> print('This {food} is {adjective}.'.format(
b8d4dbb2938a Merged revisions 65253 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 48577 diff changeset	143 ... food='spam', adjective='absolutely horrible'))
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	144 This spam is absolutely horrible.
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	145
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	146 Positional and keyword arguments can be arbitrarily combined::
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	147
48578 b8d4dbb2938a Merged revisions 65253 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 48577 diff changeset	148 >>> print('The story of {0}, {1}, and {other}.'.format('Bill', 'Manfred',
b8d4dbb2938a Merged revisions 65253 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 48577 diff changeset	149 other='Georg'))
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	150 The story of Bill, Manfred, and Georg.
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	151
55797 afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	152 ``'!a'`` (apply :func:`ascii`), ``'!s'`` (apply :func:`str`) and ``'!r'``
afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	153 (apply :func:`repr`) can be used to convert the value before it is formatted::
afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	154
afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	155 >>> import math
afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	156 >>> print('The value of PI is approximately {}.'.format(math.pi))
afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	157 The value of PI is approximately 3.14159265359.
afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	158 >>> print('The value of PI is approximately {!r}.'.format(math.pi))
afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	159 The value of PI is approximately 3.141592653589793.
afbb2b2ff6f7 Merged revisions 74613,74615,74619-74620,74622 via svnmerge from Georg Brandl <georg@python.org> parents: 55584 diff changeset	160
55584 5fbac09c0e91 Merged revisions 74264 via svnmerge from Georg Brandl <georg@python.org> parents: 55580 diff changeset	161 An optional ``':'`` and format specifier can follow the field name. This allows
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	162 greater control over how the value is formatted. The following example
68121 9861dc118322 Issue #11304: Input/output tutorial - PI is rounded not truncated. Raymond Hettinger <python@rcn.com> parents: 65137 diff changeset	163 rounds Pi to three places after the decimal.
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	164
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	165 >>> import math
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	166 >>> print('The value of PI is approximately {0:.3f}.'.format(math.pi))
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	167 The value of PI is approximately 3.142.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	168
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	169 Passing an integer after the ``':'`` will cause that field to be a minimum
55580 7b495c8f2a24 Merged revisions 73941-73943,74076,74094,74186,74211-74214,74247,74254,74262,74311,74334,74368 via svnmerge from Georg Brandl <georg@python.org> parents: 54927 diff changeset	170 number of characters wide. This is useful for making tables pretty. ::
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	171
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	172 >>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 7678}
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	173 >>> for name, phone in table.items():
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	174 ... print('{0:10} ==> {1:10d}'.format(name, phone))
50563 93cf3a6ead63 Merged revisions 68226 via svnmerge from Georg Brandl <georg@python.org> parents: 48668 diff changeset	175 ...
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	176 Jack ==> 4098
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	177 Dcab ==> 7678
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	178 Sjoerd ==> 4127
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	179
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	180 If you have a really long format string that you don't want to split up, it
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	181 would be nice if you could reference the variables to be formatted by name
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	182 instead of by position. This can be done by simply passing the dict and using
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	183 square brackets ``'[]'`` to access the keys ::
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	184
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	185 >>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 8637678}
48578 b8d4dbb2938a Merged revisions 65253 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 48577 diff changeset	186 >>> print('Jack: {0[Jack]:d}; Sjoerd: {0[Sjoerd]:d}; '
b8d4dbb2938a Merged revisions 65253 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 48577 diff changeset	187 'Dcab: {0[Dcab]:d}'.format(table))
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	188 Jack: 4098; Sjoerd: 4127; Dcab: 8637678
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	189
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	190 This could also be done by passing the table as keyword arguments with the '**'
55580 7b495c8f2a24 Merged revisions 73941-73943,74076,74094,74186,74211-74214,74247,74254,74262,74311,74334,74368 via svnmerge from Georg Brandl <georg@python.org> parents: 54927 diff changeset	191 notation. ::
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	192
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	193 >>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 8637678}
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	194 >>> print('Jack: {Jack:d}; Sjoerd: {Sjoerd:d}; Dcab: {Dcab:d}'.format(**table))
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	195 Jack: 4098; Sjoerd: 4127; Dcab: 8637678
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	196
68411 87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	197 This is particularly useful in combination with the built-in function
87167b08312f Fix markup in inputoutput.rst. Ezio Melotti <ezio.melotti@gmail.com> parents: 68285 diff changeset	198 :func:`vars`, which returns a dictionary containing all local variables.
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	199
51776 d06a3ebf306f Merged revisions 69846 via svnmerge from Mark Dickinson <dickinsm@gmail.com> parents: 50569 diff changeset	200 For a complete overview of string formatting with :meth:`str.format`, see
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	201 :ref:`formatstrings`.
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	202
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	203
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	204 Old string formatting
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	205 ---------------------
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	206
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	207 The ``%`` operator can also be used for string formatting. It interprets the
65137 521eac31a893 Migrate to Sphinx 1.0 C language constructs. Georg Brandl <georg@python.org> parents: 64763 diff changeset	208 left argument much like a :c:func:`sprintf`\ -style format string to be applied
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	209 to the right argument, and returns the string resulting from this formatting
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	210 operation. For example::
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	211
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	212 >>> import math
48655 1635891b18e8 #3503: fix print statements in 3k doc. Georg Brandl <georg@python.org> parents: 48578 diff changeset	213 >>> print('The value of PI is approximately %5.3f.' % math.pi)
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	214 The value of PI is approximately 3.142.
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	215
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	216 Since :meth:`str.format` is quite new, a lot of Python code still uses the ``%``
55584 5fbac09c0e91 Merged revisions 74264 via svnmerge from Georg Brandl <georg@python.org> parents: 55580 diff changeset	217 operator. However, because this old style of formatting will eventually be
5fbac09c0e91 Merged revisions 74264 via svnmerge from Georg Brandl <georg@python.org> parents: 55580 diff changeset	218 removed from the language, :meth:`str.format` should generally be used.
47283 f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	219
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	220 More information can be found in the :ref:`old-string-formatting` section.
f28cbab11acd Merged revisions 63655 via svnmerge from Benjamin Peterson <benjamin@python.org> parents: 44999 diff changeset	221
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	222
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	223 .. _tut-files:
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	224
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	225 Reading and Writing Files
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	226 =========================
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	227
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	228 .. index::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	229 builtin: open
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	230 object: file
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	231
64763 bed950cbd0c0 Add cross-references to the glossary entry for file objects. Antoine Pitrou <solipsis@pitrou.net> parents: 55797 diff changeset	232 :func:`open` returns a :term:`file object`, and is most commonly used with
bed950cbd0c0 Add cross-references to the glossary entry for file objects. Antoine Pitrou <solipsis@pitrou.net> parents: 55797 diff changeset	233 two arguments: ``open(filename, mode)``.
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	234
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	235 ::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	236
44396 6556f3f22c19 Merged revisions 59605-59624 via svnmerge from Christian Heimes <christian@cheimes.de> parents: 43440 diff changeset	237 >>> f = open('/tmp/workfile', 'w')
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	238
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	239 .. XXX str(f) is <io.TextIOWrapper object at 0x82e8dc4>
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	240
43115 95d6fe2e8e0e Tutorial update for 3.0 by Paul Dubois. Guido van Rossum <guido@python.org> parents: 42604 diff changeset	241 >>> print(f)
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	242 <open file '/tmp/workfile', mode 'w' at 80a0960>
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	243
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	244 The first argument is a string containing the filename. The second argument is
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	245 another string containing a few characters describing the way in which the file
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	246 will be used. mode can be ``'r'`` when the file will only be read, ``'w'``
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	247 for only writing (an existing file with the same name will be erased), and
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	248 ``'a'`` opens the file for appending; any data written to the file is
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	249 automatically added to the end. ``'r+'`` opens the file for both reading and
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	250 writing. The mode argument is optional; ``'r'`` will be assumed if it's
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	251 omitted.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	252
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	253 Normally, files are opened in :dfn:`text mode`, that means, you read and write
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	254 strings from and to the file, which are encoded in a specific encoding (the
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	255 default being UTF-8). ``'b'`` appended to the mode opens the file in
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	256 :dfn:`binary mode`: now the data is read and written in the form of bytes
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	257 objects. This mode should be used for all files that don't contain text.
43440 8d7e93b47cab Clarify the difference between text and binary files. I'm not sure the Skip Montanaro <skip@pobox.com> parents: 43418 diff changeset	258
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	259 In text mode, the default is to convert platform-specific line endings (``\n``
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	260 on Unix, ``\r\n`` on Windows) to just ``\n`` on reading and ``\n`` back to
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	261 platform-specific line endings on writing. This behind-the-scenes modification
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	262 to file data is fine for text files, but will corrupt binary data like that in
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	263 :file:`JPEG` or :file:`EXE` files. Be very careful to use binary mode when
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	264 reading and writing such files.
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	265
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	266
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	267 .. _tut-filemethods:
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	268
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	269 Methods of File Objects
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	270 -----------------------
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	271
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	272 The rest of the examples in this section will assume that a file object called
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	273 ``f`` has already been created.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	274
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	275 To read a file's contents, call ``f.read(size)``, which reads some quantity of
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	276 data and returns it as a string or bytes object. size is an optional numeric
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	277 argument. When size is omitted or negative, the entire contents of the file
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	278 will be read and returned; it's your problem if the file is twice as large as
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	279 your machine's memory. Otherwise, at most size bytes are read and returned.
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	280 If the end of the file has been reached, ``f.read()`` will return an empty
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	281 string (``''``). ::
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	282
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	283 >>> f.read()
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	284 'This is the entire file.\n'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	285 >>> f.read()
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	286 ''
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	287
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	288 ``f.readline()`` reads a single line from the file; a newline character (``\n``)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	289 is left at the end of the string, and is only omitted on the last line of the
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	290 file if the file doesn't end in a newline. This makes the return value
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	291 unambiguous; if ``f.readline()`` returns an empty string, the end of the file
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	292 has been reached, while a blank line is represented by ``'\n'``, a string
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	293 containing only a single newline. ::
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	294
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	295 >>> f.readline()
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	296 'This is the first line of the file.\n'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	297 >>> f.readline()
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	298 'Second line of the file\n'
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	299 >>> f.readline()
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	300 ''
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	301
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	302 ``f.readlines()`` returns a list containing all the lines of data in the file.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	303 If given an optional parameter sizehint, it reads that many bytes from the
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	304 file and enough more to complete a line, and returns the lines from that. This
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	305 is often used to allow efficient reading of a large file by lines, but without
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	306 having to load the entire file in memory. Only complete lines will be returned.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	307 ::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	308
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	309 >>> f.readlines()
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	310 ['This is the first line of the file.\n', 'Second line of the file\n']
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	311
43418 0c8fec76111c Merged revisions 58211-58220 via svnmerge from Thomas Wouters <thomas@python.org> parents: 43219 diff changeset	312 An alternative approach to reading lines is to loop over the file object. This is
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	313 memory efficient, fast, and leads to simpler code::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	314
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	315 >>> for line in f:
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	316 ... print(line, end='')
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	317 ...
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	318 This is the first line of the file.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	319 Second line of the file
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	320
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	321 The alternative approach is simpler but does not provide as fine-grained
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	322 control. Since the two approaches manage line buffering differently, they
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	323 should not be mixed.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	324
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	325 ``f.write(string)`` writes the contents of string to the file, returning
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	326 the number of characters written. ::
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	327
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	328 >>> f.write('This is a test\n')
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	329 15
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	330
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	331 To write something other than a string, it needs to be converted to a string
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	332 first::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	333
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	334 >>> value = ('the answer', 42)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	335 >>> s = str(value)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	336 >>> f.write(s)
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	337 18
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	338
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	339 ``f.tell()`` returns an integer giving the file object's current position in the
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	340 file, measured in bytes from the beginning of the file. To change the file
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	341 object's position, use ``f.seek(offset, from_what)``. The position is computed
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	342 from adding offset to a reference point; the reference point is selected by
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	343 the from_what argument. A from_what value of 0 measures from the beginning
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	344 of the file, 1 uses the current file position, and 2 uses the end of the file as
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	345 the reference point. from_what can be omitted and defaults to 0, using the
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	346 beginning of the file as the reference point. ::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	347
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	348 >>> f = open('/tmp/workfile', 'rb+')
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	349 >>> f.write(b'0123456789abcdef')
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	350 16
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	351 >>> f.seek(5) # Go to the 6th byte in the file
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	352 5
50563 93cf3a6ead63 Merged revisions 68226 via svnmerge from Georg Brandl <georg@python.org> parents: 48668 diff changeset	353 >>> f.read(1)
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	354 b'5'
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	355 >>> f.seek(-3, 2) # Go to the 3rd byte before the end
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	356 13
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	357 >>> f.read(1)
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	358 b'd'
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	359
48668 e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	360 In text files (those opened without a ``b`` in the mode string), only seeks
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	361 relative to the beginning of the file are allowed (the exception being seeking
e2c706f9906c #3524: fix up some old-style IO descriptions. Georg Brandl <georg@python.org> parents: 48666 diff changeset	362 to the very file end with ``seek(0, 2)``).
50563 93cf3a6ead63 Merged revisions 68226 via svnmerge from Georg Brandl <georg@python.org> parents: 48668 diff changeset	363
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	364 When you're done with a file, call ``f.close()`` to close it and free up any
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	365 system resources taken up by the open file. After calling ``f.close()``,
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	366 attempts to use the file object will automatically fail. ::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	367
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	368 >>> f.close()
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	369 >>> f.read()
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	370 Traceback (most recent call last):
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	371 File "<stdin>", line 1, in ?
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	372 ValueError: I/O operation on closed file
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	373
48563 b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	374 It is good practice to use the :keyword:`with` keyword when dealing with file
b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	375 objects. This has the advantage that the file is properly closed after its
b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	376 suite finishes, even if an exception is raised on the way. It is also much
b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	377 shorter than writing equivalent :keyword:`try`\ -\ :keyword:`finally` blocks::
b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	378
b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	379 >>> with open('/tmp/workfile', 'r') as f:
b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	380 ... read_data = f.read()
b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	381 >>> f.closed
b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	382 True
b51cd5d3795c Merged revisions 65012,65035,65037-65040,65048,65057,65077,65091-65095,65097-65099,65127-65128,65131,65133-65136,65139,65149-65151,65155,65158-65159,65176-65178,65183-65184,65187-65190,65192,65194 via svnmerge from Georg Brandl <georg@python.org> parents: 47283 diff changeset	383
55580 7b495c8f2a24 Merged revisions 73941-73943,74076,74094,74186,74211-74214,74247,74254,74262,74311,74334,74368 via svnmerge from Georg Brandl <georg@python.org> parents: 54927 diff changeset	384 File objects have some additional methods, such as :meth:`~file.isatty` and
7b495c8f2a24 Merged revisions 73941-73943,74076,74094,74186,74211-74214,74247,74254,74262,74311,74334,74368 via svnmerge from Georg Brandl <georg@python.org> parents: 54927 diff changeset	385 :meth:`~file.truncate` which are less frequently used; consult the Library
7b495c8f2a24 Merged revisions 73941-73943,74076,74094,74186,74211-74214,74247,74254,74262,74311,74334,74368 via svnmerge from Georg Brandl <georg@python.org> parents: 54927 diff changeset	386 Reference for a complete guide to file objects.
42604 9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	387
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	388
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	389 .. _tut-pickle:
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	390
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	391 The :mod:`pickle` Module
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	392 ------------------------
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	393
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	394 .. index:: module: pickle
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	395
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	396 Strings can easily be written to and read from a file. Numbers take a bit more
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	397 effort, since the :meth:`read` method only returns strings, which will have to
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	398 be passed to a function like :func:`int`, which takes a string like ``'123'``
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	399 and returns its numeric value 123. However, when you want to save more complex
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	400 data types like lists, dictionaries, or class instances, things get a lot more
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	401 complicated.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	402
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	403 Rather than have users be constantly writing and debugging code to save
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	404 complicated data types, Python provides a standard module called :mod:`pickle`.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	405 This is an amazing module that can take almost any Python object (even some
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	406 forms of Python code!), and convert it to a string representation; this process
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	407 is called :dfn:`pickling`. Reconstructing the object from the string
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	408 representation is called :dfn:`unpickling`. Between pickling and unpickling,
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	409 the string representing the object may have been stored in a file or data, or
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	410 sent over a network connection to some distant machine.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	411
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	412 If you have an object ``x``, and a file object ``f`` that's been opened for
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	413 writing, the simplest way to pickle the object takes only one line of code::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	414
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	415 pickle.dump(x, f)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	416
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	417 To unpickle the object again, if ``f`` is a file object which has been opened
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	418 for reading::
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	419
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	420 x = pickle.load(f)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	421
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	422 (There are other variants of this, used when pickling many objects or when you
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	423 don't want to write the pickled data to a file; consult the complete
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	424 documentation for :mod:`pickle` in the Python Library Reference.)
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	425
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	426 :mod:`pickle` is the standard way to make Python objects which can be stored and
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	427 reused by other programs or by a future invocation of the same program; the
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	428 technical term for this is a :dfn:`persistent` object. Because :mod:`pickle` is
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	429 so widely used, many authors who write Python extensions take care to ensure
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	430 that new data types such as matrices can be properly pickled and unpickled.
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	431
9e1529bf0442 Move the 3k reST doc tree in place. Georg Brandl <georg@python.org> parents: diff changeset	432

Mercurial > cpython-lru_cache-weakref

annotate Doc/tutorial/inputoutput.rst @ 74006:88198b93ff2f