118 lines
3.5 KiB
ReStructuredText
118 lines
3.5 KiB
ReStructuredText
.. XXX this whole file is outdated
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:mod:`StringIO` --- Read and write strings as files
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===================================================
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.. module:: StringIO
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:synopsis: Read and write strings as if they were files.
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This module implements a file-like class, :class:`StringIO`, that reads and
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writes a string buffer (also known as *memory files*). See the description of
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file objects for operations (section :ref:`bltin-file-objects`). (For
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standard strings, see :class:`str`.)
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.. class:: StringIO([buffer])
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When a :class:`StringIO` object is created, it can be initialized to an existing
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string by passing the string to the constructor. If no string is given, the
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:class:`StringIO` will start empty. In both cases, the initial file position
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starts at zero.
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The following methods of :class:`StringIO` objects require special mention:
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.. method:: StringIO.getvalue()
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Retrieve the entire contents of the "file" at any time before the
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:class:`StringIO` object's :meth:`close` method is called.
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.. method:: StringIO.close()
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Free the memory buffer.
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Example usage::
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import StringIO
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output = StringIO.StringIO()
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output.write('First line.\n')
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print('Second line.', file=output)
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# Retrieve file contents -- this will be
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# 'First line.\nSecond line.\n'
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contents = output.getvalue()
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# Close object and discard memory buffer --
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# .getvalue() will now raise an exception.
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output.close()
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:mod:`cStringIO` --- Faster version of :mod:`StringIO`
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======================================================
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.. module:: cStringIO
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:synopsis: Faster version of StringIO, but not subclassable.
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.. moduleauthor:: Jim Fulton <jim@zope.com>
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.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
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The module :mod:`cStringIO` provides an interface similar to that of the
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:mod:`StringIO` module. Heavy use of :class:`StringIO.StringIO` objects can be
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made more efficient by using the function :func:`StringIO` from this module
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instead.
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Since this module provides a factory function which returns objects of built-in
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types, there's no way to build your own version using subclassing. Use the
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original :mod:`StringIO` module in that case.
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Unlike the memory files implemented by the :mod:`StringIO` module, those
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provided by this module are not able to accept strings that cannot be
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encoded in plain ASCII.
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Calling :func:`StringIO` with a string parameter populates
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the object with the buffer representation of the string, instead of
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encoding the string.
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Another difference from the :mod:`StringIO` module is that calling
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:func:`StringIO` with a string parameter creates a read-only object. Unlike an
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object created without a string parameter, it does not have write methods.
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These objects are not generally visible. They turn up in tracebacks as
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:class:`StringI` and :class:`StringO`.
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The following data objects are provided as well:
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.. data:: InputType
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The type object of the objects created by calling :func:`StringIO` with a string
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parameter.
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.. data:: OutputType
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The type object of the objects returned by calling :func:`StringIO` with no
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parameters.
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There is a C API to the module as well; refer to the module source for more
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information.
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Example usage::
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import cStringIO
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output = cStringIO.StringIO()
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output.write('First line.\n')
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print('Second line.', file=output)
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# Retrieve file contents -- this will be
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# 'First line.\nSecond line.\n'
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contents = output.getvalue()
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# Close object and discard memory buffer --
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# .getvalue() will now raise an exception.
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output.close()
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