Why Does Overriding __getattribute__ To Proxy A Value Screw Up Isinstance?

Why does this happen? class IsInstanceScrewer(object): def __init__(self, value): self.value = value def __getattribute__(self, name): if name in ('value',

Solution 1:

__getattribute__ is returning the __class__ of the wrapped value instead of its own __class__:

>>> class IsInstanceScrewer(object):
    def __init__(self, value):
        self.value = value

    def __getattribute__(self, name):
        print name
        if name in ('value',):
            return object.__getattribute__(self, name)
        value = object.__getattribute__(self, 'value')
        return object.__getattribute__(value, name)

>>> isinstance(IsInstanceScrewer(False), bool)
__class__
True
>>> isinstance(IsInstanceScrewer([1, 2, 3]), list)
__class__
True

This may be desired behavior or not depending on what you're doing.