[issue12203] isinstance not functioning as documented

[R. David Murray]

R. David Murray <rdmurray at bitdance.com> added the comment:

You are correct, B is not an instance of A.  But both B and A are instances of 'type':

>>> class A:
...   pass
...
>>> class B(A):
...    pass
...
>>> isinstance(A, type)
True
>>> isinstance(B, type)
True
>>> 

And type is a subclass of object.  isinstance is correct, because Python is consistent.  As we said, *everything* is an object.

If you want to know if something is a class, you can check isinstance(X, type):

>>> a = A()
>>> isinstance(a, type)
False

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue12203>
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