Wild suggestion:     Make None.__hash__ writable. E.g.     None.__hash__ = lambda : 0 # Currently raises AttributeError: 'NoneType' object attribute '__hash__' is read-only Best wishes Rob Cliffe On 01/12/2022 11:02, Oscar Benjamin wrote:

On Thu, 1 Dec 2022 at 06:56, Chris Angelico wrote:

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On Thu, 1 Dec 2022 at 17:26, Yoni Lavi wrote:

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So it's not like it's even possible to require this generally for all objects. Well, I mean, in theory you could require that objects whose hash isn't otherwise defined get given the hash of zero. That doesn't violate any of the actual rules of hashes, but it does make those hashes quite suboptimal :)

It's interesting how id() and hash() have opposite requirements (id must return a unique number among concurrently-existing objects, hash must return the same number among comparing-equal objects), yet a hash can be built on an id. This also demonstrates a significant reason why None is special: it's a singleton that only compares equal to itself. The reason for using id for hash in other cases is to make different instances have different hashes but there is only ever one instance of None. A singleton class can have a hash function that matches identity based equality without using id: any constant hash function will do.

-- Oscar _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-leave@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/MTTJJN2H... Code of Conduct: http://python.org/psf/codeofconduct/