[Python-Dev] Usefulness of binary compatibility accross Python versions? (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Sat Dec 16 14:14:06 EST 2017

On Sat, 16 Dec 2017 19:37:54 +0100 Antoine Pitrou <solipsis at pitrou.net> wrote:

Currently, you can pass a moduleapiversion to PyModuleCreate2(), but that function is for specialists only :-) ("""Most uses of this function should be using PyModuleCreate() instead; only use this if you are sure you need it.""")

Ah, it turns out I misunderstood that piece of documentation and also what PEP 3121 really did w.r.t the module API check.

PyModule_Create() is actually a macro calling PyModule_Create2() with the version number is was compiled against!

#ifdef Py_LIMITED_API #define PyModule_Create(module)
PyModule_Create2(module, PYTHON_ABI_VERSION) #else #define PyModule_Create(module)
PyModule_Create2(module, PYTHON_API_VERSION) #endif

And there's already a check for that version number in moduleobject.c: https://github.com/python/cpython/blob/master/Objects/moduleobject.c#L114

That check is always invoked when calling PyModule_Create() and PyModule_Create2(). Currently it merely invokes a warning, but we can easily turn that into an error.

(with apologies to Martin von Löwis for not fully understanding what he did at the time :-))

Regards

Antoine.

More information about the Python-Dev mailing list