I used to think so, but cls.__subclasses__() makes it possible to just walk the type tree at some later point. I find the lack of state to be a feature. (Normal

I used to think so, but cls.__subclasses__() makes it possible to just walk the type tree at some later point. I find the lack of state to be a feature. (Normally with a hook like you're talking about, you'd add the class to some list somewhere, which can get out of sync.)