1 

     2 :mod:`textwrap` --- Text wrapping and filling

     3 =============================================

     4 

     5 .. module:: textwrap

     6    :synopsis: Text wrapping and filling

     7 .. moduleauthor:: Greg Ward <gward@python.net>

     8 .. sectionauthor:: Greg Ward <gward@python.net>

     9 

    10 

    11 .. versionadded:: 2.3

    12 

    13 The :mod:`textwrap` module provides two convenience functions, :func:`wrap` and

    14 :func:`fill`, as well as :class:`TextWrapper`, the class that does all the work,

    15 and a utility function  :func:`dedent`.  If you're just wrapping or filling one

    16 or two  text strings, the convenience functions should be good enough;

    17 otherwise,  you should use an instance of :class:`TextWrapper` for efficiency.

    18 

    19 

    20 .. function:: wrap(text[, width[, ...]])

    21 

    22    Wraps the single paragraph in *text* (a string) so every line is at most *width*

    23    characters long.  Returns a list of output lines, without final newlines.

    24 

    25    Optional keyword arguments correspond to the instance attributes of

    26    :class:`TextWrapper`, documented below.  *width* defaults to ``70``.

    27 

    28 

    29 .. function:: fill(text[, width[, ...]])

    30 

    31    Wraps the single paragraph in *text*, and returns a single string containing the

    32    wrapped paragraph.  :func:`fill` is shorthand for  ::

    33 

    34       "\n".join(wrap(text, ...))

    35 

    36    In particular, :func:`fill` accepts exactly the same keyword arguments as

    37    :func:`wrap`.

    38 

    39 Both :func:`wrap` and :func:`fill` work by creating a :class:`TextWrapper`

    40 instance and calling a single method on it.  That instance is not reused, so for

    41 applications that wrap/fill many text strings, it will be more efficient for you

    42 to create your own :class:`TextWrapper` object.

    43 

    44 Text is preferably wrapped on whitespaces and right after the hyphens in

    45 hyphenated words; only then will long words be broken if necessary, unless

    46 :attr:`TextWrapper.break_long_words` is set to false.

    47 

    48 An additional utility function, :func:`dedent`, is provided to remove

    49 indentation from strings that have unwanted whitespace to the left of the text.

    50 

    51 

    52 .. function:: dedent(text)

    53 

    54    Remove any common leading whitespace from every line in *text*.

    55 

    56    This can be used to make triple-quoted strings line up with the left edge of the

    57    display, while still presenting them in the source code in indented form.

    58 

    59    Note that tabs and spaces are both treated as whitespace, but they are not

    60    equal: the lines ``"  hello"`` and ``"\thello"`` are considered to have no

    61    common leading whitespace.  (This behaviour is new in Python 2.5; older versions

    62    of this module incorrectly expanded tabs before searching for common leading

    63    whitespace.)

    64 

    65    For example::

    66 

    67       def test():

    68           # end first line with \ to avoid the empty line!

    69           s = '''\

    70           hello

    71             world

    72           '''

    73           print repr(s)          # prints '    hello\n      world\n    '

    74           print repr(dedent(s))  # prints 'hello\n  world\n'

    75 

    76 

    77 .. class:: TextWrapper(...)

    78 

    79    The :class:`TextWrapper` constructor accepts a number of optional keyword

    80    arguments.  Each argument corresponds to one instance attribute, so for example

    81    ::

    82 

    83       wrapper = TextWrapper(initial_indent="* ")

    84 

    85    is the same as  ::

    86 

    87       wrapper = TextWrapper()

    88       wrapper.initial_indent = "* "

    89 

    90    You can re-use the same :class:`TextWrapper` object many times, and you can

    91    change any of its options through direct assignment to instance attributes

    92    between uses.

    93 

    94    The :class:`TextWrapper` instance attributes (and keyword arguments to the

    95    constructor) are as follows:

    96 

    97 

    98    .. attribute:: width

    99 

   100       (default: ``70``) The maximum length of wrapped lines.  As long as there

   101       are no individual words in the input text longer than :attr:`width`,

   102       :class:`TextWrapper` guarantees that no output line will be longer than

   103       :attr:`width` characters.

   104 

   105 

   106    .. attribute:: expand_tabs

   107 

   108       (default: ``True``) If true, then all tab characters in *text* will be

   109       expanded to spaces using the :meth:`expandtabs` method of *text*.

   110 

   111 

   112    .. attribute:: replace_whitespace

   113 

   114       (default: ``True``) If true, each whitespace character (as defined by

   115       ``string.whitespace``) remaining after tab expansion will be replaced by a

   116       single space.

   117 

   118       .. note::

   119 

   120          If :attr:`expand_tabs` is false and :attr:`replace_whitespace` is true,

   121          each tab character will be replaced by a single space, which is *not*

   122          the same as tab expansion.

   123 

   124 

   125    .. attribute:: drop_whitespace

   126 

   127       (default: ``True``) If true, whitespace that, after wrapping, happens to

   128       end up at the beginning or end of a line is dropped (leading whitespace in

   129       the first line is always preserved, though).

   130 

   131       .. versionadded:: 2.6

   132          Whitespace was always dropped in earlier versions.

   133 

   134 

   135    .. attribute:: initial_indent

   136 

   137       (default: ``''``) String that will be prepended to the first line of

   138       wrapped output.  Counts towards the length of the first line.

   139 

   140 

   141    .. attribute:: subsequent_indent

   142 

   143       (default: ``''``) String that will be prepended to all lines of wrapped

   144       output except the first.  Counts towards the length of each line except

   145       the first.

   146 

   147 

   148    .. attribute:: fix_sentence_endings

   149 

   150       (default: ``False``) If true, :class:`TextWrapper` attempts to detect

   151       sentence endings and ensure that sentences are always separated by exactly

   152       two spaces.  This is generally desired for text in a monospaced font.

   153       However, the sentence detection algorithm is imperfect: it assumes that a

   154       sentence ending consists of a lowercase letter followed by one of ``'.'``,

   155       ``'!'``, or ``'?'``, possibly followed by one of ``'"'`` or ``"'"``,

   156       followed by a space.  One problem with this is algorithm is that it is

   157       unable to detect the difference between "Dr." in ::

   158 

   159          [...] Dr. Frankenstein's monster [...]

   160 

   161       and "Spot." in ::

   162 

   163          [...] See Spot. See Spot run [...]

   164 

   165       :attr:`fix_sentence_endings` is false by default.

   166 

   167       Since the sentence detection algorithm relies on ``string.lowercase`` for

   168       the definition of "lowercase letter," and a convention of using two spaces

   169       after a period to separate sentences on the same line, it is specific to

   170       English-language texts.

   171 

   172 

   173    .. attribute:: break_long_words

   174 

   175       (default: ``True``) If true, then words longer than :attr:`width` will be

   176       broken in order to ensure that no lines are longer than :attr:`width`.  If

   177       it is false, long words will not be broken, and some lines may be longer

   178       than :attr:`width`.  (Long words will be put on a line by themselves, in

   179       order to minimize the amount by which :attr:`width` is exceeded.)

   180 

   181 

   182    .. attribute:: break_on_hyphens

   183 

   184       (default: ``True``) If true, wrapping will occur preferably on whitespaces

   185       and right after hyphens in compound words, as it is customary in English.

   186       If false, only whitespaces will be considered as potentially good places

   187       for line breaks, but you need to set :attr:`break_long_words` to false if

   188       you want truly insecable words.  Default behaviour in previous versions

   189       was to always allow breaking hyphenated words.

   190 

   191       .. versionadded:: 2.6

   192 

   193 

   194    :class:`TextWrapper` also provides two public methods, analogous to the

   195    module-level convenience functions:

   196 

   197    .. method:: wrap(text)

   198 

   199       Wraps the single paragraph in *text* (a string) so every line is at most

   200       :attr:`width` characters long.  All wrapping options are taken from

   201       instance attributes of the :class:`TextWrapper` instance. Returns a list

   202       of output lines, without final newlines.

   203 

   204 

   205    .. method:: fill(text)

   206 

   207       Wraps the single paragraph in *text*, and returns a single string

   208       containing the wrapped paragraph.

   209