Mailman 3 May 2021 - capi-sig

New script: add Python 3.10 support to your C extensions without losing Python 3.6 support
by Victor Stinner 07 May '22

07 May '22

Hi, I wrote a new script which adds Python 3.10 support to your C extensions without losing Python 3.6 support: https://github.com/pythoncapi/pythoncapi_compat For example, it replaces "op->ob_type" with "Py_TYPE(op)" and replaces "frame->f_back" with "_PyFrame_GetBackBorrow(frame)". It relies on the pythoncapi_compat.h header file that I wrote to implement Python 3.9 and Python 3.10 on old Python versions. Examples: Py_NewRef() and PyThreadState_GetFrame(). The _PyFrame_GetBackBorrow() function doesn't exist in the Python C API, it's only provided by pythoncapi_compat.h to ease the migration of C extensions. I advise you to replace _PyFrame_GetBackBorrow() (borrowed reference) with PyFrame_GetBack() (strong reference). The PyFrame_GetBack() function was added to Python 3.9 and pythoncapi_compat.h provides it on older Python versions. This project is related to my PEP 620 "Hide implementation details from the C API" which tries to make the C API more abstract to later allow to implement new optimization in CPython and to make other Python implementations like PyPy faster when running C extensions. This project only targets extension modules written in C by using directly the "Python.h" API. I advise you to use Cython or HPy to no longer be bothered with incompatible C API changes at every Python release ;-) * https://cython.org/ * https://hpy.readthedocs.io/ I hope that my script will facilitate migration of C extensions to HPy. Victor -- Night gathers, and now my watch begins. It shall not end until my death.

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ANN: expy 0.6.5 released!
by Yingjie Lan 16 Apr '22

16 Apr '22

EXPY is an express way to extend Python! EXPY provides a way to extend python in an elegant way. For more information and a tutorial, see: http://expy.sourceforge.net/ What's new: 1. Correct treatment of __init__ method. 2. Give warnings of missing Py_INCREF on appropriate special type methods. 3. Documentation update. Cheers, Yingjie

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ANNOUNCE: PyBindGen 0.8
by Gustavo Carneiro 10 Mar '22

10 Mar '22

The other day I released PyBindGen 0.8. Main news is that it features a new experimental header file scanner based on pygccxml (i.e., it's similar to py++ in scope, if not in maturity, but does not use boost.pythonunderneath). == What == PyBindGen is a Python module that is geared to generating C/C++ code that binds a C/C++ library for Python. It does so without extensive use of either C++ templates or C pre-processor macros. It has modular handling of C/C++ types, and can be easily extended with Python plugins. The generated code is almost as clean as what a human programmer would write, and does not depend on any library or header files besides Python itself. == Where == https://launchpad.net/pybindgen/ == NEWS == - Support C++ instance attributes through getter/setter methods - Support functions as methods of C++ classes - Support the PyObject* type - Support unsigned int, C strings (char*) (from Mark Lee) - Add basic support for enum types - New experimental automatic module generator based on C/C++ header file scanner and annotations in comments, using pygccxml - Some bug fixes -- Gustavo J. A. M. Carneiro INESC Porto, Telecommunications and Multimedia Unit "The universe is always one step beyond logic." -- Frank Herbert

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C API equivalent to abc.ABCMeta.register?
by Daniel Stutzbach 02 Mar '22

02 Mar '22

I'm the author of an extension module (blist) that provides a type that fits the MutableSequence API. Is there a canonical way for me to register the type as a MutableSequence from the C API? -- Daniel Stutzbach, Ph.D. President, Stutzbach Enterprises, LLC <http://stutzbachenterprises.com>

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Software Development - Application Development - Game Development
by Gary 10 Jan '22

10 Jan '22

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Mail l8st
by casperssidekick 10 Jul '21

10 Jul '21

Sent from my Verizon, Samsung Galaxy smartphone

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Py_FrozenMain and the stable ABI
by Petr Viktorin 21 May '21

21 May '21

I tried getting Py_FrozenMain from ctypes.pythonapi, but I get "undefined symbol". This is the only symbol from the Stable ABI that behaves this way. (It was re-added in [bpo-42591].) So far, I haven't found what makes the symbol different, but I assume this is deliberate, since it happens on Windows as well (see a [test PR]). It seems to be included when Python is compiled as a shared library. Is this something we want as part of the stable ABI? If we do, it would be good to always export it. AFAICS, Py_FrozenMain is only used with freeze.py for a custom Python build with frozen modules included. [bpo-42591]: https://bugs.python.org/issue42591 [test PR]: https://github.com/encukou/cpython/pull/12/checks?check_run_id=2508147377 $ ./python Python 3.11.0a0 (heads/pep652-ctypes:315d97b64aa, May 5 2021, 11:49:17) [GCC 11.1.1 20210428 (Red Hat 11.1.1-1)] on linux Type "help", "copyright", "credits" or "license" for more information. >>> import ctypes >>> ctypes.pythonapi.Py_FrozenMain Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/pviktori/dev/cpython/Lib/ctypes/__init__.py", line 387, in __getattr__ func = self.__getitem__(name) File "/home/pviktori/dev/cpython/Lib/ctypes/__init__.py", line 392, in __getitem__ func = self._FuncPtr((name_or_ordinal, self)) AttributeError: ./python: undefined symbol: Py_FrozenMain

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