cpython/Doc/c-api/marshal.rst

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.. highlight:: c
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.. _marshalling-utils:
Data marshalling support
========================
Merged revisions 71920-71923,71925-71929,71931-71934,71937 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r71920 | jeroen.ruigrok | 2009-04-25 21:44:55 +0200 (za, 25 apr 2009) | 5 lines Issue #4129: More documentation pointers about int -> Py_ssize_t. Also fix up the documentation for PyObject_GC_Resize(). It seems that since it first got documented, the documentation was actually for _PyObject_GC_Resize(). ........ r71921 | jeroen.ruigrok | 2009-04-25 21:46:19 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Documentation notes for int -> Py_ssize_t changes. ........ r71922 | jeroen.ruigrok | 2009-04-25 21:49:05 +0200 (za, 25 apr 2009) | 2 lines Reformat, since I've been busy here anyway. ........ r71923 | jeroen.ruigrok | 2009-04-25 21:54:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Add a versionchanged notice for a few forgotten entries. ........ r71925 | jeroen.ruigrok | 2009-04-25 22:37:39 +0200 (za, 25 apr 2009) | 2 lines Since it's a macro, actually refer to it as such instead of function. ........ r71926 | jeroen.ruigrok | 2009-04-25 22:40:10 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71927 | jeroen.ruigrok | 2009-04-25 22:41:40 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71928 | jeroen.ruigrok | 2009-04-25 22:43:30 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71929 | jeroen.ruigrok | 2009-04-25 22:44:58 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71931 | jeroen.ruigrok | 2009-04-25 22:50:27 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71932 | jeroen.ruigrok | 2009-04-25 22:55:39 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71933 | jeroen.ruigrok | 2009-04-25 22:58:35 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71934 | jeroen.ruigrok | 2009-04-25 23:02:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: field changed from int to Py_ssize_t. ........ r71937 | jeroen.ruigrok | 2009-04-25 23:16:05 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: document int -> Py_ssize_t changes. ........
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These routines allow C code to work with serialized objects using the same
data format as the :mod:`marshal` module. There are functions to write data
into the serialization format, and additional functions that can be used to
read the data back. Files used to store marshalled data must be opened in
binary mode.
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Numeric values are stored with the least significant byte first.
Merged revisions 71920-71923,71925-71929,71931-71934,71937 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r71920 | jeroen.ruigrok | 2009-04-25 21:44:55 +0200 (za, 25 apr 2009) | 5 lines Issue #4129: More documentation pointers about int -> Py_ssize_t. Also fix up the documentation for PyObject_GC_Resize(). It seems that since it first got documented, the documentation was actually for _PyObject_GC_Resize(). ........ r71921 | jeroen.ruigrok | 2009-04-25 21:46:19 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Documentation notes for int -> Py_ssize_t changes. ........ r71922 | jeroen.ruigrok | 2009-04-25 21:49:05 +0200 (za, 25 apr 2009) | 2 lines Reformat, since I've been busy here anyway. ........ r71923 | jeroen.ruigrok | 2009-04-25 21:54:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Add a versionchanged notice for a few forgotten entries. ........ r71925 | jeroen.ruigrok | 2009-04-25 22:37:39 +0200 (za, 25 apr 2009) | 2 lines Since it's a macro, actually refer to it as such instead of function. ........ r71926 | jeroen.ruigrok | 2009-04-25 22:40:10 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71927 | jeroen.ruigrok | 2009-04-25 22:41:40 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71928 | jeroen.ruigrok | 2009-04-25 22:43:30 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71929 | jeroen.ruigrok | 2009-04-25 22:44:58 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71931 | jeroen.ruigrok | 2009-04-25 22:50:27 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71932 | jeroen.ruigrok | 2009-04-25 22:55:39 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71933 | jeroen.ruigrok | 2009-04-25 22:58:35 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71934 | jeroen.ruigrok | 2009-04-25 23:02:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: field changed from int to Py_ssize_t. ........ r71937 | jeroen.ruigrok | 2009-04-25 23:16:05 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: document int -> Py_ssize_t changes. ........
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The module supports two versions of the data format: version 0 is the
historical version, version 1 shares interned strings in the file, and upon
unmarshalling. Version 2 uses a binary format for floating point numbers.
``Py_MARSHAL_VERSION`` indicates the current file format (currently 2).
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.. c:function:: void PyMarshal_WriteLongToFile(long value, FILE *file, int version)
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Marshal a :c:type:`long` integer, *value*, to *file*. This will only write
Merged revisions 71920-71923,71925-71929,71931-71934,71937 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r71920 | jeroen.ruigrok | 2009-04-25 21:44:55 +0200 (za, 25 apr 2009) | 5 lines Issue #4129: More documentation pointers about int -> Py_ssize_t. Also fix up the documentation for PyObject_GC_Resize(). It seems that since it first got documented, the documentation was actually for _PyObject_GC_Resize(). ........ r71921 | jeroen.ruigrok | 2009-04-25 21:46:19 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Documentation notes for int -> Py_ssize_t changes. ........ r71922 | jeroen.ruigrok | 2009-04-25 21:49:05 +0200 (za, 25 apr 2009) | 2 lines Reformat, since I've been busy here anyway. ........ r71923 | jeroen.ruigrok | 2009-04-25 21:54:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Add a versionchanged notice for a few forgotten entries. ........ r71925 | jeroen.ruigrok | 2009-04-25 22:37:39 +0200 (za, 25 apr 2009) | 2 lines Since it's a macro, actually refer to it as such instead of function. ........ r71926 | jeroen.ruigrok | 2009-04-25 22:40:10 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71927 | jeroen.ruigrok | 2009-04-25 22:41:40 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71928 | jeroen.ruigrok | 2009-04-25 22:43:30 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71929 | jeroen.ruigrok | 2009-04-25 22:44:58 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71931 | jeroen.ruigrok | 2009-04-25 22:50:27 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71932 | jeroen.ruigrok | 2009-04-25 22:55:39 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71933 | jeroen.ruigrok | 2009-04-25 22:58:35 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71934 | jeroen.ruigrok | 2009-04-25 23:02:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: field changed from int to Py_ssize_t. ........ r71937 | jeroen.ruigrok | 2009-04-25 23:16:05 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: document int -> Py_ssize_t changes. ........
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the least-significant 32 bits of *value*; regardless of the size of the
native :c:type:`long` type. *version* indicates the file format.
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.. c:function:: void PyMarshal_WriteObjectToFile(PyObject *value, FILE *file, int version)
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Marshal a Python object, *value*, to *file*.
*version* indicates the file format.
.. c:function:: PyObject* PyMarshal_WriteObjectToString(PyObject *value, int version)
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Return a bytes object containing the marshalled representation of *value*.
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*version* indicates the file format.
The following functions allow marshalled values to be read back in.
.. c:function:: long PyMarshal_ReadLongFromFile(FILE *file)
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Return a C :c:type:`long` from the data stream in a :c:type:`FILE\*` opened
Merged revisions 71920-71923,71925-71929,71931-71934,71937 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r71920 | jeroen.ruigrok | 2009-04-25 21:44:55 +0200 (za, 25 apr 2009) | 5 lines Issue #4129: More documentation pointers about int -> Py_ssize_t. Also fix up the documentation for PyObject_GC_Resize(). It seems that since it first got documented, the documentation was actually for _PyObject_GC_Resize(). ........ r71921 | jeroen.ruigrok | 2009-04-25 21:46:19 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Documentation notes for int -> Py_ssize_t changes. ........ r71922 | jeroen.ruigrok | 2009-04-25 21:49:05 +0200 (za, 25 apr 2009) | 2 lines Reformat, since I've been busy here anyway. ........ r71923 | jeroen.ruigrok | 2009-04-25 21:54:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Add a versionchanged notice for a few forgotten entries. ........ r71925 | jeroen.ruigrok | 2009-04-25 22:37:39 +0200 (za, 25 apr 2009) | 2 lines Since it's a macro, actually refer to it as such instead of function. ........ r71926 | jeroen.ruigrok | 2009-04-25 22:40:10 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71927 | jeroen.ruigrok | 2009-04-25 22:41:40 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71928 | jeroen.ruigrok | 2009-04-25 22:43:30 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71929 | jeroen.ruigrok | 2009-04-25 22:44:58 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71931 | jeroen.ruigrok | 2009-04-25 22:50:27 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71932 | jeroen.ruigrok | 2009-04-25 22:55:39 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71933 | jeroen.ruigrok | 2009-04-25 22:58:35 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71934 | jeroen.ruigrok | 2009-04-25 23:02:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: field changed from int to Py_ssize_t. ........ r71937 | jeroen.ruigrok | 2009-04-25 23:16:05 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: document int -> Py_ssize_t changes. ........
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for reading. Only a 32-bit value can be read in using this function,
regardless of the native size of :c:type:`long`.
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On error, sets the appropriate exception (:exc:`EOFError`) and returns
``-1``.
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.. c:function:: int PyMarshal_ReadShortFromFile(FILE *file)
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Return a C :c:type:`short` from the data stream in a :c:type:`FILE\*` opened
Merged revisions 71920-71923,71925-71929,71931-71934,71937 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r71920 | jeroen.ruigrok | 2009-04-25 21:44:55 +0200 (za, 25 apr 2009) | 5 lines Issue #4129: More documentation pointers about int -> Py_ssize_t. Also fix up the documentation for PyObject_GC_Resize(). It seems that since it first got documented, the documentation was actually for _PyObject_GC_Resize(). ........ r71921 | jeroen.ruigrok | 2009-04-25 21:46:19 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Documentation notes for int -> Py_ssize_t changes. ........ r71922 | jeroen.ruigrok | 2009-04-25 21:49:05 +0200 (za, 25 apr 2009) | 2 lines Reformat, since I've been busy here anyway. ........ r71923 | jeroen.ruigrok | 2009-04-25 21:54:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Add a versionchanged notice for a few forgotten entries. ........ r71925 | jeroen.ruigrok | 2009-04-25 22:37:39 +0200 (za, 25 apr 2009) | 2 lines Since it's a macro, actually refer to it as such instead of function. ........ r71926 | jeroen.ruigrok | 2009-04-25 22:40:10 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71927 | jeroen.ruigrok | 2009-04-25 22:41:40 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71928 | jeroen.ruigrok | 2009-04-25 22:43:30 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71929 | jeroen.ruigrok | 2009-04-25 22:44:58 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71931 | jeroen.ruigrok | 2009-04-25 22:50:27 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71932 | jeroen.ruigrok | 2009-04-25 22:55:39 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71933 | jeroen.ruigrok | 2009-04-25 22:58:35 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71934 | jeroen.ruigrok | 2009-04-25 23:02:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: field changed from int to Py_ssize_t. ........ r71937 | jeroen.ruigrok | 2009-04-25 23:16:05 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: document int -> Py_ssize_t changes. ........
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for reading. Only a 16-bit value can be read in using this function,
regardless of the native size of :c:type:`short`.
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On error, sets the appropriate exception (:exc:`EOFError`) and returns
``-1``.
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.. c:function:: PyObject* PyMarshal_ReadObjectFromFile(FILE *file)
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Return a Python object from the data stream in a :c:type:`FILE\*` opened for
reading.
On error, sets the appropriate exception (:exc:`EOFError`, :exc:`ValueError`
or :exc:`TypeError`) and returns ``NULL``.
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.. c:function:: PyObject* PyMarshal_ReadLastObjectFromFile(FILE *file)
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Return a Python object from the data stream in a :c:type:`FILE\*` opened for
reading. Unlike :c:func:`PyMarshal_ReadObjectFromFile`, this function
Merged revisions 71920-71923,71925-71929,71931-71934,71937 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r71920 | jeroen.ruigrok | 2009-04-25 21:44:55 +0200 (za, 25 apr 2009) | 5 lines Issue #4129: More documentation pointers about int -> Py_ssize_t. Also fix up the documentation for PyObject_GC_Resize(). It seems that since it first got documented, the documentation was actually for _PyObject_GC_Resize(). ........ r71921 | jeroen.ruigrok | 2009-04-25 21:46:19 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Documentation notes for int -> Py_ssize_t changes. ........ r71922 | jeroen.ruigrok | 2009-04-25 21:49:05 +0200 (za, 25 apr 2009) | 2 lines Reformat, since I've been busy here anyway. ........ r71923 | jeroen.ruigrok | 2009-04-25 21:54:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Add a versionchanged notice for a few forgotten entries. ........ r71925 | jeroen.ruigrok | 2009-04-25 22:37:39 +0200 (za, 25 apr 2009) | 2 lines Since it's a macro, actually refer to it as such instead of function. ........ r71926 | jeroen.ruigrok | 2009-04-25 22:40:10 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71927 | jeroen.ruigrok | 2009-04-25 22:41:40 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71928 | jeroen.ruigrok | 2009-04-25 22:43:30 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71929 | jeroen.ruigrok | 2009-04-25 22:44:58 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71931 | jeroen.ruigrok | 2009-04-25 22:50:27 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71932 | jeroen.ruigrok | 2009-04-25 22:55:39 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71933 | jeroen.ruigrok | 2009-04-25 22:58:35 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71934 | jeroen.ruigrok | 2009-04-25 23:02:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: field changed from int to Py_ssize_t. ........ r71937 | jeroen.ruigrok | 2009-04-25 23:16:05 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: document int -> Py_ssize_t changes. ........
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assumes that no further objects will be read from the file, allowing it to
aggressively load file data into memory so that the de-serialization can
operate from data in memory rather than reading a byte at a time from the
file. Only use these variant if you are certain that you won't be reading
anything else from the file.
On error, sets the appropriate exception (:exc:`EOFError`, :exc:`ValueError`
or :exc:`TypeError`) and returns ``NULL``.
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.. c:function:: PyObject* PyMarshal_ReadObjectFromString(const char *data, Py_ssize_t len)
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Return a Python object from the data stream in a byte buffer
containing *len* bytes pointed to by *data*.
On error, sets the appropriate exception (:exc:`EOFError`, :exc:`ValueError`
or :exc:`TypeError`) and returns ``NULL``.
Merged revisions 71920-71923,71925-71929,71931-71934,71937 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r71920 | jeroen.ruigrok | 2009-04-25 21:44:55 +0200 (za, 25 apr 2009) | 5 lines Issue #4129: More documentation pointers about int -> Py_ssize_t. Also fix up the documentation for PyObject_GC_Resize(). It seems that since it first got documented, the documentation was actually for _PyObject_GC_Resize(). ........ r71921 | jeroen.ruigrok | 2009-04-25 21:46:19 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Documentation notes for int -> Py_ssize_t changes. ........ r71922 | jeroen.ruigrok | 2009-04-25 21:49:05 +0200 (za, 25 apr 2009) | 2 lines Reformat, since I've been busy here anyway. ........ r71923 | jeroen.ruigrok | 2009-04-25 21:54:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: Add a versionchanged notice for a few forgotten entries. ........ r71925 | jeroen.ruigrok | 2009-04-25 22:37:39 +0200 (za, 25 apr 2009) | 2 lines Since it's a macro, actually refer to it as such instead of function. ........ r71926 | jeroen.ruigrok | 2009-04-25 22:40:10 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71927 | jeroen.ruigrok | 2009-04-25 22:41:40 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71928 | jeroen.ruigrok | 2009-04-25 22:43:30 +0200 (za, 25 apr 2009) | 2 lines Reformat prior to editing. ........ r71929 | jeroen.ruigrok | 2009-04-25 22:44:58 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71931 | jeroen.ruigrok | 2009-04-25 22:50:27 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: int -> Py_ssize_t documentation. ........ r71932 | jeroen.ruigrok | 2009-04-25 22:55:39 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71933 | jeroen.ruigrok | 2009-04-25 22:58:35 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: more int -> Py_ssize_t documentation. ........ r71934 | jeroen.ruigrok | 2009-04-25 23:02:34 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: field changed from int to Py_ssize_t. ........ r71937 | jeroen.ruigrok | 2009-04-25 23:16:05 +0200 (za, 25 apr 2009) | 2 lines Issue #4129: document int -> Py_ssize_t changes. ........
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