easy question on parsing python: "is not None"

[wheres pythonmonks]

Well, I am not convinced of the equivalence of not None and true:

>>> not None
True
>>> 3 is True;
False
>>> 3 is not None
True
>>>

P.S. Sorry for the top-post -- is there a way to not do top posts from
gmail?  I haven't used usenet since tin.

On Thu, Aug 5, 2010 at 11:56 AM, Roald de Vries <downaold at gmail.com> wrote:
> On Aug 5, 2010, at 5:42 PM, wheres pythonmonks wrote:
>>
>> How does "x is not None" make any sense?  "not x is None" does make sense.
>>
>> I can only surmise that in this context (preceding is) "not" is not a
>> unary right-associative operator, therefore:
>>
>> x is not None === IS_NOTEQ(X, None)
>>
>> Beside "not in" which seems to work similarly, is there other
>> syntactical sugar like this that I should be aware of?
>
> 'not None' first casts None to a bool, and then applies 'not', so 'x is not
> None' means 'x is True'.
> 'not x is None' is the same as 'not (x is None)'
>
> Cheers, Roald
> --
> http://mail.python.org/mailman/listinfo/python-list
>