Ken Jin <kenjin4...@gmail.com> added the comment:
@Serhiy > 2. Different handling of virtual subclasses: This looks like a bug. I think the union form of isinstance/issubclass should have the same behavior as the tuple form. We promise checking of virtual classes in the docs for union types: https://docs.python.org/3.10/library/functions.html#issubclass The fix seems to be changing one line of code in Objects/unionobject.c from PyType_IsSubtype to PyObject_IsSubclass. Since it isn't a large change and it's a bug, I think we can backport it to 3.10 too. @Serhiy and Guido, > 1. Different handling of None: > Ken Jin, should we treat type(None) as a subclass of int|None? I think we can avoid this special case altogether by converting all None to type(None) when creating _Py_Union. This is what the typing.Union counterpart does, and it is also what PEP 484 says about None https://www.python.org/dev/peps/pep-0484/#using-none: >>> Union[None, str].__args__ (<class 'NoneType'>, <class 'str'>) Though I know some people are opinionated about None -> type(None). This would require adding one more check at https://github.com/python/cpython/blob/3.10/Objects/unionobject.c#L266 . Maybe this? if(Py_IsNone(i_element)) i_element = &_PyNone_Type ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue44606> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
