something wrong with isinstance

[Gabriel Genellina]

En Fri, 13 Feb 2009 08:43:03 -0200, Peter Otten <__peter__ at web.de>  
escribió:
> Gabriel Genellina wrote:
>> En Fri, 13 Feb 2009 08:07:58 -0200, Carl Banks  
>> <pavlovevidence at gmail.com>
>> escribió:
>>> But that brings up another very slight possibility, though not a very
>>> likely one in this case: the behavior of isinstance can be
>>> customized.  It can happen unbeknownst to a user who subclasses a
>>> class that does that.
>>
>> Really? I didn't know that -- how do you do that?
>
>>>> class Type(type):
> ...     def __instancecheck__(self, other): return True
> ...
>>>> class A(metaclass=Type): pass
> ...
>>>> class B: pass
> ...
>>>> isinstance(B(), A)
> True
>
> See also
>
> http://www.python.org/dev/peps/pep-3119/#overloading-isinstance-and-issubclass

Ah, ok. Isn't menctioned in the main documentation though.

-- 
Gabriel Genellina