On Sat, 4 Jul 2020 at 16:51, Serhiy Storchaka <storch...@gmail.com> wrote:
> 30.06.20 18:58, Joao S. O. Bueno пише: > > I ended up writting an __eq__ - and in the process I found it is not > > _that_ straightforward due > > to having to check subclasses types when comparing. > > (given Base sequence A, child class B(A), class C(A) and class B1(B) - > > Instances of B and B1 can be > > equal, but instances of B and C should always be different) - or in > > Python, inside __eq__ : > > if not issubclass(type(other), type(self)) and not > > issubclass(type(self), type(other)): > > return False > > It would be more correct to return NotImplemented. > > Also, it is enough to test isinstance(other, type(self)) because > other.__eq__(self) be called first if the type of other is a subclass of > the type of self. > Ah - yes. Half the logic is already on the __eq__ semantics - thanks. Well, I am updating that on my code right now. Anyway I am not seeing anyone opposing this going into col...abc.Sequence - Maybe it is ok for a BPO? (yes, there is this consideration I had, and also Guido, that it would create new behavior in classes that already exist, but I saw no way that could break code not specially crafted to break with this change.) _______________________________________________ > 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/K2P4ZWF6FIRPCRKUH7IHZHMC7E3HVJER/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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