David Montague

Looking a bit more closely, I see that your error in the subclass check is because you made `ModelMetaclass` a subclass of `typing._GenericAlias`, which I don't think makes sense. You...

(Also, I understand that what I originally wrote — "require making parametrized submodels be subclasses of typing._GenericAlias" — was not equivalent to my corrected/clarified approach described in my more recent...

> Is `type(M[int]()) is not M[int]` considered acceptable? Considering that's the case for all standard library generics, I would say yes it is acceptable, though I would guess it would...

I'll also note that with standard library generics: ```python assert isinstance(M[int](), M[int]) ``` would actually raise an error, and in general I think it's not a great idea to be...

> Keep in mind that this prevented pytest from even running a single test. Fair point, that's a good reason to require that to be okay. > If something has...

I mean it's probably worth thinking about carefully, I would say I'm not convinced either way today, but I also know I haven't thought hard enough about it to have...