[issue1393] function comparing lacks NotImplemented error

[Christian Heimes]

Christian Heimes added the comment:

Additional prints make it easy to understand what happens here:

>>> class Anything:
...     def __eq__(self, other):
...         print("eq")
...         return True
...     def __ne__(self, other):
...         print("ne")
...         return False
...
>>> x = lambda: None
>>> print(x == Anything())
False
>>> print(Anything() == x)
eq
True
>>> y = object()
>>> print(y == Anything())
eq
True
>>> print(Anything() == y)
eq
True

x == Anything() doesn't invoke Anything.__eq__(). It's using
function.__eq__().

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nosy: +tiran

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Tracker <report at bugs.python.org>
<http://bugs.python.org/issue1393>
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