mirror of https://github.com/python/cpython
193 lines
6.8 KiB
ReStructuredText
193 lines
6.8 KiB
ReStructuredText
|
|
:mod:`textwrap` --- Text wrapping and filling
|
|
=============================================
|
|
|
|
.. module:: textwrap
|
|
:synopsis: Text wrapping and filling
|
|
.. moduleauthor:: Greg Ward <gward@python.net>
|
|
.. sectionauthor:: Greg Ward <gward@python.net>
|
|
|
|
|
|
.. versionadded:: 2.3
|
|
|
|
The :mod:`textwrap` module provides two convenience functions, :func:`wrap` and
|
|
:func:`fill`, as well as :class:`TextWrapper`, the class that does all the work,
|
|
and a utility function :func:`dedent`. If you're just wrapping or filling one
|
|
or two text strings, the convenience functions should be good enough;
|
|
otherwise, you should use an instance of :class:`TextWrapper` for efficiency.
|
|
|
|
|
|
.. function:: wrap(text[, width[, ...]])
|
|
|
|
Wraps the single paragraph in *text* (a string) so every line is at most *width*
|
|
characters long. Returns a list of output lines, without final newlines.
|
|
|
|
Optional keyword arguments correspond to the instance attributes of
|
|
:class:`TextWrapper`, documented below. *width* defaults to ``70``.
|
|
|
|
|
|
.. function:: fill(text[, width[, ...]])
|
|
|
|
Wraps the single paragraph in *text*, and returns a single string containing the
|
|
wrapped paragraph. :func:`fill` is shorthand for ::
|
|
|
|
"\n".join(wrap(text, ...))
|
|
|
|
In particular, :func:`fill` accepts exactly the same keyword arguments as
|
|
:func:`wrap`.
|
|
|
|
Both :func:`wrap` and :func:`fill` work by creating a :class:`TextWrapper`
|
|
instance and calling a single method on it. That instance is not reused, so for
|
|
applications that wrap/fill many text strings, it will be more efficient for you
|
|
to create your own :class:`TextWrapper` object.
|
|
|
|
An additional utility function, :func:`dedent`, is provided to remove
|
|
indentation from strings that have unwanted whitespace to the left of the text.
|
|
|
|
|
|
.. function:: dedent(text)
|
|
|
|
Remove any common leading whitespace from every line in *text*.
|
|
|
|
This can be used to make triple-quoted strings line up with the left edge of the
|
|
display, while still presenting them in the source code in indented form.
|
|
|
|
Note that tabs and spaces are both treated as whitespace, but they are not
|
|
equal: the lines ``" hello"`` and ``"\thello"`` are considered to have no
|
|
common leading whitespace. (This behaviour is new in Python 2.5; older versions
|
|
of this module incorrectly expanded tabs before searching for common leading
|
|
whitespace.)
|
|
|
|
For example::
|
|
|
|
def test():
|
|
# end first line with \ to avoid the empty line!
|
|
s = '''\
|
|
hello
|
|
world
|
|
'''
|
|
print repr(s) # prints ' hello\n world\n '
|
|
print repr(dedent(s)) # prints 'hello\n world\n'
|
|
|
|
|
|
.. class:: TextWrapper(...)
|
|
|
|
The :class:`TextWrapper` constructor accepts a number of optional keyword
|
|
arguments. Each argument corresponds to one instance attribute, so for example
|
|
::
|
|
|
|
wrapper = TextWrapper(initial_indent="* ")
|
|
|
|
is the same as ::
|
|
|
|
wrapper = TextWrapper()
|
|
wrapper.initial_indent = "* "
|
|
|
|
You can re-use the same :class:`TextWrapper` object many times, and you can
|
|
change any of its options through direct assignment to instance attributes
|
|
between uses.
|
|
|
|
The :class:`TextWrapper` instance attributes (and keyword arguments to the
|
|
constructor) are as follows:
|
|
|
|
|
|
.. attribute:: TextWrapper.width
|
|
|
|
(default: ``70``) The maximum length of wrapped lines. As long as there are no
|
|
individual words in the input text longer than :attr:`width`,
|
|
:class:`TextWrapper` guarantees that no output line will be longer than
|
|
:attr:`width` characters.
|
|
|
|
|
|
.. attribute:: TextWrapper.expand_tabs
|
|
|
|
(default: ``True``) If true, then all tab characters in *text* will be expanded
|
|
to spaces using the :meth:`expandtabs` method of *text*.
|
|
|
|
|
|
.. attribute:: TextWrapper.replace_whitespace
|
|
|
|
(default: ``True``) If true, each whitespace character (as defined by
|
|
``string.whitespace``) remaining after tab expansion will be replaced by a
|
|
single space.
|
|
|
|
.. note::
|
|
|
|
If :attr:`expand_tabs` is false and :attr:`replace_whitespace` is true, each tab
|
|
character will be replaced by a single space, which is *not* the same as tab
|
|
expansion.
|
|
|
|
|
|
.. attribute:: TextWrapper.drop_whitespace
|
|
|
|
(default: ``True``) If true, whitespace that, after wrapping, happens to end up
|
|
at the beginning or end of a line is dropped (leading whitespace in the first
|
|
line is always preserved, though).
|
|
|
|
.. versionadded:: 2.6
|
|
Whitespace was always dropped in earlier versions.
|
|
|
|
|
|
.. attribute:: TextWrapper.initial_indent
|
|
|
|
(default: ``''``) String that will be prepended to the first line of wrapped
|
|
output. Counts towards the length of the first line.
|
|
|
|
|
|
.. attribute:: TextWrapper.subsequent_indent
|
|
|
|
(default: ``''``) String that will be prepended to all lines of wrapped output
|
|
except the first. Counts towards the length of each line except the first.
|
|
|
|
|
|
.. attribute:: TextWrapper.fix_sentence_endings
|
|
|
|
(default: ``False``) If true, :class:`TextWrapper` attempts to detect sentence
|
|
endings and ensure that sentences are always separated by exactly two spaces.
|
|
This is generally desired for text in a monospaced font. However, the sentence
|
|
detection algorithm is imperfect: it assumes that a sentence ending consists of
|
|
a lowercase letter followed by one of ``'.'``, ``'!'``, or ``'?'``, possibly
|
|
followed by one of ``'"'`` or ``"'"``, followed by a space. One problem with
|
|
this is algorithm is that it is unable to detect the difference between "Dr." in
|
|
::
|
|
|
|
[...] Dr. Frankenstein's monster [...]
|
|
|
|
and "Spot." in ::
|
|
|
|
[...] See Spot. See Spot run [...]
|
|
|
|
:attr:`fix_sentence_endings` is false by default.
|
|
|
|
Since the sentence detection algorithm relies on ``string.lowercase`` for the
|
|
definition of "lowercase letter," and a convention of using two spaces after
|
|
a period to separate sentences on the same line, it is specific to
|
|
English-language texts.
|
|
|
|
|
|
.. attribute:: TextWrapper.break_long_words
|
|
|
|
(default: ``True``) If true, then words longer than :attr:`width` will be broken
|
|
in order to ensure that no lines are longer than :attr:`width`. If it is false,
|
|
long words will not be broken, and some lines may be longer than :attr:`width`.
|
|
(Long words will be put on a line by themselves, in order to minimize the amount
|
|
by which :attr:`width` is exceeded.)
|
|
|
|
:class:`TextWrapper` also provides two public methods, analogous to the
|
|
module-level convenience functions:
|
|
|
|
|
|
.. method:: TextWrapper.wrap(text)
|
|
|
|
Wraps the single paragraph in *text* (a string) so every line is at most
|
|
:attr:`width` characters long. All wrapping options are taken from instance
|
|
attributes of the :class:`TextWrapper` instance. Returns a list of output lines,
|
|
without final newlines.
|
|
|
|
|
|
.. method:: TextWrapper.fill(text)
|
|
|
|
Wraps the single paragraph in *text*, and returns a single string containing the
|
|
wrapped paragraph.
|
|
|