Inject dependency on a Typer function about in-n-out HOT 2 CLOSED

Thanks for looking into it @tlambert03, I think the workaround is simple enough for now.

from in-n-out.

yeah, I don't think this one is going to be possible, but i think it's more of a typer limitation than in-n-out, and I don't think there's anything (safe) we could do to help it along.

if I'm not mistaken, typer just doesn't support custom types? tiangolo/typer#77
so, as you no doubt found, removing in-n-out altogether from the example still gives the Type not yet supported error when typer encounters thing: Thing in the signature.

The very best we could do (and I don't like it) is to patch the __signature__ attribute of an in-n-out injected function to essentially remove injected types from the signature, so that typer simply doesn't see them when it inspects signatures here: https://github.com/tiangolo/typer/blob/50caff27573e0d1381701d24122ca9fed20d6343/typer/main.py#L548

... the problem with that is

1. it's a lie: the parameters are still in the signature, and in-n-out does allow you to pass them to the function if you wish to override injection when calling the function.
2. we actually don't know which parameters will be injected (at injection time). we only know it at call time (since providers can be registered at any point, even after decorating a function with ino.inject). So, even if we wanted to remove something, we wouldn't know it was thing that needed to be removed.

Since typer is its own dependency injection system, this one is probably going to be tough to pull off. but perhaps if tiangolo/typer#77 is addressed, we could extend support for it

from in-n-out.