On Thu, Jan 23, 2020 at 07:29:58PM -0600, Tim Peters wrote: > PyObject_RichCompareBool(x, y, op) has a (valuable!) shortcut: if x > and y are the same object, then equality comparison returns True and > inequality False. No attempt is made to execute __eq__ or __ne__ > methods in those cases. > > This has visible consequences all over the place, but they don't > appear to be documented.
This has definitely been discussed before. Here's one such thread: https://mail.python.org/pipermail/python-dev/2011-April/110945.html My recollection is that we reached a consensus that collections in general don't have to obey the invariant that `x != x` when x is a NAN. But I don't recall seeing it documented outside of the mailing lists. By my recollections, this has come up, oh, at least four times now, so perhaps there should be a FAQ answering why NAN != NAN except inside collections. -- Steven _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@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/2RGSEKNYWZXI52YZ6RNIEYAXNIWSRHWU/ Code of Conduct: http://python.org/psf/codeofconduct/
