[Doc-SIG] Does the "is" operator only matter for mutable object?

[Nick Coghlan]

On Mon, Mar 7, 2011 at 9:08 AM, Laura Creighton <lac at openend.se> wrote:
> Singleton objects such as ``True``, ``False``, and ``None`` are always
> the same object.  The canonical way to test whether an object is
> a singleton is to test for object identity, not equality.  So
>
>>>> if x is None:
>    ... do something ...
>
> not
>
>>>> if x == None:
>    ... do something ...

Careful with that - "if x is True:" and "if x is False:" (along with
s/is/==/) are almost always the wrong thing to do, but a reader could
easily generalise the above to cover those two cases as well.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia