gistfile1.py

class WeakMethodRef(object):
    def __init__(self, method):
        if getattr(method, "im_self", None):
            self.obj = weakref.ref(method.im_self)
        elif getattr(method, "im_class", None):
            self.obj = weakref.ref(method.im_class)
        else:
            self.obj = None

        if getattr(method, "im_func", None):
            method = method.im_func
        self.func = weakref.ref(method)

    def __nonzero__(self):
        if self.obj is not None and not self.obj():
            return False
        return self.func() is not None

    def __call__(self, *args, **kwargs):
        if not self:
            raise Exception("weakrefs broken")
        if self.obj is not None:
            args = (self.obj(),) + args
        return self.func()(*args, **kwargs)