Test None for an object that does not implement ==

[Larry Hudson]

On 12/24/2011 11:09 PM, GZ wrote:
> Hi,
>
> I run into a weird problem. I have a piece of code that looks like the
> following:
>
> f(...., a=None, c=None):
>      assert  (a==None)==(c==None)
>
<...>

At first glance this looked like it should be a simple boolean "and", but then I realized that 
when a and c are both unequal to None, the result would also be True.  This implies the logical 
approach would be exclusive-or (^).  Try this expression:

      not ((a==None) ^ (c==None))

OTOH, if what you really want is simply to check that both are None (my first impression), then 
it's simply:

      (a==None) and (c==None)

Most of the replies you're getting here seem unnecessarily complicated.

> Thanks,
> gz

     -=- Larry -=-