1 :mod:`textwrap` --- Text wrapping and filling 2 ============================================= 3 4 .. module:: textwrap 5 :synopsis: Text wrapping and filling 6 .. moduleauthor:: Greg Ward <gward (a] python.net> 7 .. sectionauthor:: Greg Ward <gward (a] python.net> 8 9 .. versionadded:: 2.3 10 11 **Source code:** :source:`Lib/textwrap.py` 12 13 -------------- 14 15 The :mod:`textwrap` module provides two convenience functions, :func:`wrap` and 16 :func:`fill`, as well as :class:`TextWrapper`, the class that does all the work, 17 and a utility function :func:`dedent`. If you're just wrapping or filling one 18 or two text strings, the convenience functions should be good enough; 19 otherwise, you should use an instance of :class:`TextWrapper` for efficiency. 20 21 .. function:: wrap(text[, width[, ...]]) 22 23 Wraps the single paragraph in *text* (a string) so every line is at most *width* 24 characters long. Returns a list of output lines, without final newlines. 25 26 Optional keyword arguments correspond to the instance attributes of 27 :class:`TextWrapper`, documented below. *width* defaults to ``70``. 28 29 See the :meth:`TextWrapper.wrap` method for additional details on how 30 :func:`wrap` behaves. 31 32 33 .. function:: fill(text[, width[, ...]]) 34 35 Wraps the single paragraph in *text*, and returns a single string containing the 36 wrapped paragraph. :func:`fill` is shorthand for :: 37 38 "\n".join(wrap(text, ...)) 39 40 In particular, :func:`fill` accepts exactly the same keyword arguments as 41 :func:`wrap`. 42 43 Both :func:`wrap` and :func:`fill` work by creating a :class:`TextWrapper` 44 instance and calling a single method on it. That instance is not reused, so for 45 applications that wrap/fill many text strings, it will be more efficient for you 46 to create your own :class:`TextWrapper` object. 47 48 Text is preferably wrapped on whitespaces and right after the hyphens in 49 hyphenated words; only then will long words be broken if necessary, unless 50 :attr:`TextWrapper.break_long_words` is set to false. 51 52 An additional utility function, :func:`dedent`, is provided to remove 53 indentation from strings that have unwanted whitespace to the left of the text. 54 55 56 .. function:: dedent(text) 57 58 Remove any common leading whitespace from every line in *text*. 59 60 This can be used to make triple-quoted strings line up with the left edge of the 61 display, while still presenting them in the source code in indented form. 62 63 Note that tabs and spaces are both treated as whitespace, but they are not 64 equal: the lines ``" hello"`` and ``"\thello"`` are considered to have no 65 common leading whitespace. (This behaviour is new in Python 2.5; older versions 66 of this module incorrectly expanded tabs before searching for common leading 67 whitespace.) 68 69 For example:: 70 71 def test(): 72 # end first line with \ to avoid the empty line! 73 s = '''\ 74 hello 75 world 76 ''' 77 print repr(s) # prints ' hello\n world\n ' 78 print repr(dedent(s)) # prints 'hello\n world\n' 79 80 81 .. class:: TextWrapper(...) 82 83 The :class:`TextWrapper` constructor accepts a number of optional keyword 84 arguments. Each argument corresponds to one instance attribute, so for example 85 :: 86 87 wrapper = TextWrapper(initial_indent="* ") 88 89 is the same as :: 90 91 wrapper = TextWrapper() 92 wrapper.initial_indent = "* " 93 94 You can re-use the same :class:`TextWrapper` object many times, and you can 95 change any of its options through direct assignment to instance attributes 96 between uses. 97 98 The :class:`TextWrapper` instance attributes (and keyword arguments to the 99 constructor) are as follows: 100 101 102 .. attribute:: width 103 104 (default: ``70``) The maximum length of wrapped lines. As long as there 105 are no individual words in the input text longer than :attr:`width`, 106 :class:`TextWrapper` guarantees that no output line will be longer than 107 :attr:`width` characters. 108 109 110 .. attribute:: expand_tabs 111 112 (default: ``True``) If true, then all tab characters in *text* will be 113 expanded to spaces using the :meth:`expandtabs` method of *text*. 114 115 116 .. attribute:: replace_whitespace 117 118 (default: ``True``) If true, after tab expansion but before wrapping, 119 the :meth:`wrap` method will replace each whitespace character 120 with a single space. The whitespace characters replaced are 121 as follows: tab, newline, vertical tab, formfeed, and carriage 122 return (``'\t\n\v\f\r'``). 123 124 .. note:: 125 126 If :attr:`expand_tabs` is false and :attr:`replace_whitespace` is true, 127 each tab character will be replaced by a single space, which is *not* 128 the same as tab expansion. 129 130 .. note:: 131 132 If :attr:`replace_whitespace` is false, newlines may appear in the 133 middle of a line and cause strange output. For this reason, text should 134 be split into paragraphs (using :meth:`str.splitlines` or similar) 135 which are wrapped separately. 136 137 138 .. attribute:: drop_whitespace 139 140 (default: ``True``) If true, whitespace at the beginning and ending of 141 every line (after wrapping but before indenting) is dropped. 142 Whitespace at the beginning of the paragraph, however, is not dropped 143 if non-whitespace follows it. If whitespace being dropped takes up an 144 entire line, the whole line is dropped. 145 146 .. versionadded:: 2.6 147 Whitespace was always dropped in earlier versions. 148 149 150 .. attribute:: initial_indent 151 152 (default: ``''``) String that will be prepended to the first line of 153 wrapped output. Counts towards the length of the first line. The empty 154 string is not indented. 155 156 157 .. attribute:: subsequent_indent 158 159 (default: ``''``) String that will be prepended to all lines of wrapped 160 output except the first. Counts towards the length of each line except 161 the first. 162 163 164 .. attribute:: fix_sentence_endings 165 166 (default: ``False``) If true, :class:`TextWrapper` attempts to detect 167 sentence endings and ensure that sentences are always separated by exactly 168 two spaces. This is generally desired for text in a monospaced font. 169 However, the sentence detection algorithm is imperfect: it assumes that a 170 sentence ending consists of a lowercase letter followed by one of ``'.'``, 171 ``'!'``, or ``'?'``, possibly followed by one of ``'"'`` or ``"'"``, 172 followed by a space. One problem with this is algorithm is that it is 173 unable to detect the difference between "Dr." in :: 174 175 [...] Dr. Frankenstein's monster [...] 176 177 and "Spot." in :: 178 179 [...] See Spot. See Spot run [...] 180 181 :attr:`fix_sentence_endings` is false by default. 182 183 Since the sentence detection algorithm relies on ``string.lowercase`` for 184 the definition of "lowercase letter," and a convention of using two spaces 185 after a period to separate sentences on the same line, it is specific to 186 English-language texts. 187 188 189 .. attribute:: break_long_words 190 191 (default: ``True``) If true, then words longer than :attr:`width` will be 192 broken in order to ensure that no lines are longer than :attr:`width`. If 193 it is false, long words will not be broken, and some lines may be longer 194 than :attr:`width`. (Long words will be put on a line by themselves, in 195 order to minimize the amount by which :attr:`width` is exceeded.) 196 197 198 .. attribute:: break_on_hyphens 199 200 (default: ``True``) If true, wrapping will occur preferably on whitespaces 201 and right after hyphens in compound words, as it is customary in English. 202 If false, only whitespaces will be considered as potentially good places 203 for line breaks, but you need to set :attr:`break_long_words` to false if 204 you want truly insecable words. Default behaviour in previous versions 205 was to always allow breaking hyphenated words. 206 207 .. versionadded:: 2.6 208 209 210 :class:`TextWrapper` also provides two public methods, analogous to the 211 module-level convenience functions: 212 213 .. method:: wrap(text) 214 215 Wraps the single paragraph in *text* (a string) so every line is at most 216 :attr:`width` characters long. All wrapping options are taken from 217 instance attributes of the :class:`TextWrapper` instance. Returns a list 218 of output lines, without final newlines. If the wrapped output has no 219 content, the returned list is empty. 220 221 222 .. method:: fill(text) 223 224 Wraps the single paragraph in *text*, and returns a single string 225 containing the wrapped paragraph. 226 227
