New submission from Simon Cross <hodges...@gmail.com>:
The documentation for PyNumber_InPlacePower [1] reads: This is the equivalent of the Python statement o1 **= o2 when o3 is Py_None, or an in-place variant of pow(o1, o2, o3) otherwise. If o3 is to be ignored, pass Py_None in its place (passing NULL for o3 would cause an illegal memory access). However, if a class A implements __ipow__ then PyNumber_InPlacePower(o1, o2, o3) ALWAYS ignores o3 if o1 is an instance of A. This happens because if A implements __ipow__ then PyNumber_InPlacePower always calls the nb_inplace_power slot [2] and the slot always drops the third argument [3]. This appears to have always been the case in Python, so likely a small documentation patch is all that is required. If people agree, I will open a documentation pull request. [1] https://docs.python.org/3/c-api/number.html?highlight=pynumber_inplacepower#c.PyNumber_InPlacePower [2] https://github.com/python/cpython/blob/master/Objects/abstract.c#L1164 [3] https://github.com/python/cpython/blob/master/Objects/typeobject.c#L6631-L6636 ---------- components: C API messages: 377758 nosy: hodgestar priority: normal severity: normal status: open title: PyNumber_InPlacePower ignores o3 if o1 implements __ipow__ type: behavior versions: Python 3.10, Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue41903> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
