In <[EMAIL PROTECTED]>, Rene Pijlman wrote:
> Steven D'Aprano:
>>Rene Pijlman:
>>> Mr.Rech:
>>>> def __eq__(self, other):
>>>> try:
>>>> return self.an_attribute == other.an_attribute
>>>> except AttributeError:
>>>> return False
>>>
>>> This may give unexpected results when you compare a foo with an instance
>>> of a completely different type that happens to have an attribute called
>>> 'an_attribute'.
>>
>>That's a trade-off, isn't it?
>>
>>On the one hand, you risk false negatives, by refusing to compare against
>>things you didn't think of.
>
> Well no, when comparing against things you didn't think of the __eq__
> shouldn't return a false False, it should return NotImplemented. After
> all, the things you didn't think of are not (yet) implemented.
I think Steven thinks that it is possible that you compare to an object of
a different type which has the same attributes as expected by the
`__eq__()` method. If the first test is `isinstance()` for the "correct"
type you rule out those cases and give a false `False`.
Ciao,
Marc 'BlackJack' Rintsch
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