FYI, I'll re-iterate something I said before, there is a different approach you can take here if this is just an issue of proxying.  Use two different proxy types depending on if the proxied object is callable or not:


class Proxy:
    # all the proxy stuff...


class CallableProxy(Proxy):
    def __call__(self, *args, **kwargs):
        ...


def proxy(obj):
    if callable(obj):
        return CallableProxy(obj)
    else:
        return Proxy(obj)


If that isn't a viable alternative then please explain your use case in more detail.  I'm sure we can find a solution that works for you.