On Tue, Dec 15, 2015 at 8:04 AM, Victor Stinner <victor.stin...@gmail.com> wrote: > Is it expected that "not x.__eq__(y)" can be different than > "x.__ne__(y)"? Is it part of the Python semantic?
In Numpy, `x != y` returns an array of bools, while `not x == y` creates an array of bools and then tries to convert it to a bool, which fails, because a non-singleton Numpy array is not allowed to be converted to a bool. But in the context of `if`, both `not x == y` and `x != y` will fail. >From the docs, on implementing comparison: https://docs.python.org/3/reference/datamodel.html#object.__ne__ """ By default, __ne__() delegates to __eq__() and inverts the result unless it is NotImplemented. There are no other implied relationships among the comparison operators, for example, the truth of (x<y or x==y) does not imply x<=y. """ _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
