Document GenericMeta

[gvanrossum]

There are some use cases where GenericMeta is essential (e.g. when combining Generic[T] with a custom metaclass). We should document that it exist, and what you can safely override (the implementation looks a bit brittle if people were to start subclassing this with impunity).

[ilevkivskyi]

Possible solution is to re-use docstrings https://github.com/python/typing/blob/master/src/typing.py#L927-L947 that already mention several restrictions. Maybe we should also add a warning like "Any use of GenericMeta except explicitly documented here is subject to breakage without warning."

[gvanrossum]

I think we should also provide several examples.

…

On May 16, 2017 3:47 AM, "Ivan Levkivskyi" ***@***.***> wrote: Possible solution is to re-use docstrings https://github.com/python/ typing/blob/master/src/typing.py#L927-L947 that already mention several restrictions. Maybe we should also add a warning like "Any use of GenericMeta except explicitly documented here is subject to breakage without warning." — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#430 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACwrMgrkYb4fubFQq3sKTXcMvzjBA64zks5r6X7RgaJpZM4NbqkG> .

[JelleZijlstra]

GenericMeta no longer exists, so we shouldn't document it.