eryksun added the comment:
Since Python has multiple inheritance, it could be misconstrued as a
conjunctive test. For example, if c is an instance of C, which subclasses both
A and B, then someone might think isinstance(c, (A, B)) requires c to be an
instance of both A and B. The description could clarify that it's a disjunctive
test with short circuiting.
class MetaA(type):
def __instancecheck__(self, other):
print('MetaA.__instancecheck__')
return False
class A(metaclass=MetaA): pass
>>> isinstance(1, (A, int))
MetaA.__instancecheck__
True
>>> isinstance(1, (int, A))
True
----------
keywords: +easy
nosy: +eryksun
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue25432>
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