author | johnathan.white@2718R8BGH51.accenture.com |
Mon, 08 Mar 2010 18:45:03 +0000 | |
changeset 46 | b6935a90ca64 |
parent 1 | 2fb8b9db1c86 |
permissions | -rw-r--r-- |
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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` and :class:`unicode`.) |
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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 :class:`StringIO` object can accept either Unicode or 8-bit strings, but |
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mixing the two may take some care. If both are used, 8-bit strings that cannot |
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be interpreted as 7-bit ASCII (that use the 8th bit) will cause a |
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:exc:`UnicodeError` to be raised when :meth:`getvalue` is called. |
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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. See the note above |
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for information about mixing Unicode and 8-bit strings; such mixing can cause |
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this method to raise :exc:`UnicodeError`. |
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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 >>output, 'Second line.' |
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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 Unicode strings that cannot be |
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encoded as plain ASCII strings. |
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Calling :func:`StringIO` with a Unicode string parameter populates |
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the object with the buffer representation of the Unicode 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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Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
109 |
|
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
110 |
import cStringIO |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
111 |
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2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
112 |
output = cStringIO.StringIO() |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
113 |
output.write('First line.\n') |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
114 |
print >>output, 'Second line.' |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
115 |
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2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
116 |
# Retrieve file contents -- this will be |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
117 |
# 'First line.\nSecond line.\n' |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
118 |
contents = output.getvalue() |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
119 |
|
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
120 |
# Close object and discard memory buffer -- |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
121 |
# .getvalue() will now raise an exception. |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
122 |
output.close() |
2fb8b9db1c86
Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff
changeset
|
123 |