finding object using IS instead of ==

[Andrew Bennetts]

On Wed, Aug 27, 2003 at 09:35:46PM -0700, Mark Hahn wrote:
> Clarification: Is there a FASTER way that takes advantage of the IS
> equivalence than using the available == method.  I assume the == method does
> a linear search, except for a dict key lookup, which is not what I'm talking
> about.
> 
> Obviously if two references are the same object (IS equivalent) then they
> are == also so you could find based on == and then check for IS, but I want
> something faster.

Actually, (x != y) doesn't necessarily imply that (x is not y):

>>> class NeverEqual:
...     def __eq__(self, other):
...         return False
... 
>>> ne = NeverEqual()                   
>>> ne == ne
False
>>> ne is ne
True

I'm not sure how much this matters to you, though :)

-Andrew.