isinstance(False, int)

Jack Diederich jackdied at gmail.com
Fri Mar 5 21:58:01 CET 2010


On Fri, Mar 5, 2010 at 2:54 PM, Steven D'Aprano
<steve at remove-this-cybersource.com.au> wrote:
> On Fri, 05 Mar 2010 15:01:23 -0400, Rolando Espinoza La Fuente wrote:
>
>> On Fri, Mar 5, 2010 at 2:32 PM, mk <mrkafk at gmail.com> wrote:
>>> Arnaud Delobelle wrote:
>>>
>>>>>>> 1 == True
>>>>
>>>> True
>>>>>>>
>>>>>>> 0 == False
>>>>
>>>> True
>>>>
>>>> So what's your question?
>>>
>>> Well nothing I'm just kind of bewildered: I'd expect smth like that in
>>> Perl, but not in Python.. Although I can understand the rationale after
>>> skimming PEP 285, I still don't like it very much.
>>>
>>>
>> So, the pythonic way to check for True/False should be:
>>
>>>>> 1 is True
>> False
>
> Why do you need to check for True/False?
>

You should never check for "is" False/True but always check for
equality.  The reason is that many types support the equality (__eq__)
and boolen (__bool__ in 3x) protocols.  If you check equality these
will be invoked, if you check identity ("is") they won't.

-Jack



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