class Foo(object):

    def __init__(self):
        print self.__dict__
        super(Foo, self).__setattr__("data", {"bing": 2})

    def __getattr__(self, name):
        return self.data.get(name)

    def __setattr__(self, name, value):
        self.data[name] = value

    @property
    def bar(self):
        return 3

    @property
    def bing(self):
        raise AttributeError("blarg")

f = Foo()
f.foo = 2
print f.foo
print f.bar
print f.bing