http://mail.python.org/pipermail/python-dev/2008-June/079988.html

Python 2.6 should stick with PyString_* in its codebase.  The PyBytes_* names
in the spirit of 3.0 are available via a #define only.  See the email thread.

#1629: Renamed Py_Size, Py_Type and Py_Refcnt to Py_SIZE, Py_TYPE and Py_REFCNT. Macros for b/w compatibility are available.

backwards compatibility. Add Py_Refcnt, Py_Type, Py_Size, and
PyVarObject_HEAD_INIT.

- change the pyexpat wrapper to not be so sensitive to this detail of the
  Expat implementation (the ex-crasher test still passes)

Use Py_UnpackTuple instead of PyArg_ParseTuple where possible.

using a custom, nearly-identical macro. This probably changes how some of
these functions are compiled, which may result in fractionally slower (or
faster) execution. Considering the nature of traversal, visiting much of the
address space in unpredictable patterns, I'd argue the code readability and
maintainability is well worth it ;P

tp_clear methods.

Probably should be backported.

Most of these can be backported.

added missing API hooks

(e.g. cStringIO, ucnhash, etc)

In C++, it's an error to pass a string literal to a char* function
without a const_cast().  Rather than require every C++ extension
module to put a cast around string literals, fix the API to state the
const-ness.

I focused on parts of the API where people usually pass literals:
PyArg_ParseTuple() and friends, Py_BuildValue(), PyMethodDef, the type
slots, etc.  Predictably, there were a large set of functions that
needed to be fixed as a result of these changes.  The most pervasive
change was to make the keyword args list passed to
PyArg_ParseTupleAndKewords() to be a const char *kwlist[].

One cast was required as a result of the changes:  A type object
mallocs the memory for its tp_doc slot and later frees it.
PyTypeObject says that tp_doc is const char *; but if the type was
created by type_new(), we know it is safe to cast to char *.

Remove duplicate declarations from compile.h

in latin_1, but Python incorrectly assumes it is in UTF-8 format

Will backport.

in pyexpat.GetInputContext. Will backport to 2.4.

73: Restore support for Python 2.1.
74: Factor the previous change differently
79: Conditionalize usage of PyTuple_Pack.

the remaining data in the buffer (which it had done happily without reporting
any results)

this depends on a new feature in Expat added in 1.95.8

years

* Py_BuildValue("(OOO)",a,b,c)  -->  PyTuple_Pack(3,a,b,c)
* Py_BuildValue("()",a)         -->  PyTuple_New(0)
* Py_BuildValue("O", a)         -->  Py_INCREF(a)

This patch was provided by Jeremy Kloth, and corresponds to pyexpat.c
1.77 in the PyXML CVS.

If the callback raised an exception but did not set curexc_traceback,
the trace function was called with PyTrace_RETURN.  That is, the trace
function was called with an exception set.  The main loop detected the
exception when the trace function returned; it complained and disabled
tracing.

Fix the logic error so that PyTrace_RETURN only occurs if the callback
returned normally.

The trace function must be called for exceptions, too.  So we had
to add new functionality to call with PyTrace_EXCEPTION.  (Leads to a
rather ugly ifdef / else block that contains only a '}'.)

Reverse the logic and name of NOFIX_TRACE to FIX_TRACE.

Joint work with Fred.

ElementDeclHandler by Expat.
Fixes SF bug #676990.

60: Added support for the SkippedEntityHandler, new in Expat 1.95.4.
61: Added support for namespace prefixes, which can be enabled by setting the
    "namespace_prefixes" attribute on the parser object.
65: Disable profiling changes for Python 2.0 and 2.1.
66: Update pyexpat to export the Expat 1.95.5 XML_GetFeatureList()
    information, and tighten up a type declaration now that Expat is using
    an incomplete type rather than a void * for the XML_Parser type.
67: Clarified a comment.
    Added support for XML_UseForeignDTD(), new in Expat 1.95.5.
68: Refactor to avoid partial duplication of the code to construct an
    ExpatError instance, and actually conform to the API for the exception
    instance as well.
69: Remove some spurious trailing whitespace.
    Add a special external-entity-ref handler that gets installed once a
    handler has raised a Python exception; this can cancel actual parsing
    earlier if there's an external entity reference in the input data
    after the the Python excpetion has been raised.
70: Untabify APPEND.
71: Backport PyMODINIT_FUNC for 2.2 and earlier.

Will backport.

[ 617309 ] getframe hook (Psyco #1)
[ 617311 ] Tiny profiling info (Psyco #2)
[ 617312 ] debugger-controlled jumps (Psyco #3)

These are forward ports from 2.2.2.

XML_Parser, which happens to be a pointer type, not an XML_Parser*.
This generated warnings when compiled with Expat 1.95.5, which no
longer defines XML_Parser to be void*.

the "safety" parentheses since some older compilers refuse to compile
the module then, claiming that static initializers are non-constant.

This doesn't actually make any difference for Python, since these
definitions are not used when compiling with a version of Python that
already defines the PyDoc_* macros.

-- replace then with slightly faster PyObject_Call(o,a,NULL).  (The
difference is that the latter requires a to be a tuple; the former
allows other values and wraps them in a tuple if necessary; it
involves two more levels of C function calls to accomplish all that.)