Interesting behaviour of the assignment

[Neelakantan Krishnaswami]

On Fri, 29 Dec 2000 09:07:21 +0200 (IST), Moshe Zadka wrote:
>On Thu, 28 Dec 2000, "Alex Martelli" <aleaxit at yahoo.com> wrote:
>
>> (Actually, in the case of None, the semantics of is and
>> == are identical, but 'is' can be a tiny little bit faster).
>
>No.
>
>>>> class FoolAlex:
>...         def __cmp__(self, other):
>...             return cmp(None, other)
>...
>>>> FoolAlex() == None
>1
>>>> FoolAlex() is None
>0
>
> Which is why, in code I write, I always use "x is None" -- faster
> and more reliable.

Oddly enough, this is why I always use '=='. I figure that if the
class's author wanted the object to test the same as None, he or
she had a good reason. :)


Neel