On Tue, Oct 1, 2019 at 8:48 AM Ben Rudiak-Gould <benrud...@gmail.com <mailto:benrud...@gmail.com>> wrote:Is it? Subtyping in type theory satisfies some axioms, one of which is transitivity. The addition of the ABCs broke transitivity:>>> issubclass(list, object) True >>> issubclass(object, collections.abc.Hashable) True >>> issubclass(list, collections.abc.Hashable) False
This isn't really the fault of ABCs, it's a consequence of the fact that subclasses can nobble certain methods by setting them to None. The non-transitivity was already there, it's just that issubclass() doesn't always detect it. -- Greg _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/EQPDWDKVYVHWLZYV2KPEB3YUTXUOUBIB/ Code of Conduct: http://python.org/psf/codeofconduct/
