How does the Python isinstance function work internally? Is there anything I can do to alter its results, like define a special function inside a class or something? Here's my use case:
class Decorator:
def __init__(self, decorated):
self._decorated = decorated
def __call__(self):
return self._decorated()
@Decorator
class Foo:
pass
f = Foo()
# How can I make this be true?
isinstance(f, Foo)
Decorator acts almost like a mixin, except a mixing wouldn't be appropriate here. Is there any way I can make the above code work? I should also note that the isinstance line also gives the following error:
isinstance(f, Foo)
TypeError: isinstance() arg 2 must be a type or tuple of types
How about the following:
def Decorator(decorated):
class Dec(decorated):
def __call__(self):
print 'in decorated __call__'
return decorated.__call__(self)
return Dec
@Decorator
class Foo(object):
def __call__(self):
print 'in original __call__'
f = Foo()
# How can I make this be true?
print isinstance(f, Foo)
With the above code:
isinstance(f, Foo) works;f() calls the decorated method which then forwards to the original method.The basic idea is to make sure that the decorated Foo is still a class, and to also make sure that the decorated Foo is a subclass of the original Foo.
P.S. The purpose of all this is not entirely clear to me; it might be that metaclasses are a better way to achieve what you're trying to do.