<var> is None vs. <var> == None

Steven D'Aprano steve at REMOVE-THIS-cybersource.com.au
Sat Jan 24 02:16:51 CET 2009


On Fri, 23 Jan 2009 16:28:15 -0800, Gary Herron wrote:

> If something
> *equals* None, it also *is* None.  This is a consequence of the fact
> that there is only ever one value of None anywhere in the system.
...
> The only way something can *equal* None is if it *is* None.


>>> class Empty:
...     def __eq__(self, other):
...             return not bool(other)
...
>>> e = Empty()
>>> e == None
True
>>> e is None
False



-- 
Steven



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