Implement app typing (Any)

[Dreamsorcerer]

Demonstration of adding app typing to a library lazily by using Any.

[asvetlov]

Sorry for the late review, I was busy with other tasks.

How to make a library work with both the new approach and the latest published 3.8.1 version assuming that mypy --strict is used for checks?

[Dreamsorcerer]

Sorry for the late review, I was busy with other tasks.

How to make a library work with both the new approach and the latest published 3.8.1 version assuming that mypy --strict is used for checks?

To support both aiohttp 3.8 and (if merged) 3.9? I'm not sure there's an easy way, I think we frequently just bump the minimum supported version (e.g. we bumped aiohttp-session to 3.8+ recently to support a new argument).

If someone really wanted to do that, then you could possibly do some kind of version check to use either Application or "Application[Any]". But, given that we don't even provide security updates to older releases of aiohttp, it doesn't seem like a situation worth supporting, we should just encourage users to upgrade.