Provide an accurate return type for Injected and SyncInjected

[eirikur-nc]

What

Specify return type for Injected and SyncInjected

Why

Previously, the return type was Any. It was therefore necessary to specify the type of every injected argument like so

def some_route(self, foo: Foo = Injected(Foo), bar: Bar = Injected(Bar)):

For developers who rely on a static type checker that infers argument types by default values (e.g. PyRight), this can now be simplified to

def some_route(self, foo=Injected(Foo), bar=Injected(Bar)):

without loss of type information.

As far as I can tell, mypy still doesn't infer argument types like PyRight does (see python/mypy#3090). I have therefore left the code examples as-is.

[matyasrichter]

Hi! Happy to merge this, thanks! Can you take a look at the failing linter? Feel free to adjust things - I just don't really have time to look into it right now.

[eirikur-nc]

Shoot, we're now running into this long-standing issue with mypy and abstract base classes
python-injector/injector#143

And a whole lot more context here
python/mypy#4717

Would you be OK with disabling this particular rule as suggested here?
python/mypy#4717 (comment)

[matyasrichter]

TBH I'm fine even with switching the linter to pyright, I've had a better experience with it on other projects anyway. Disabling the rule is also okay, though. If you could do it it would be great, otherwise I'll get to it during the week.

[eirikur-nc]

TBH I'm fine even with switching the linter to pyright, I've had a better experience with it on other projects anyway. Disabling the rule is also okay, though. If you could do it it would be great, otherwise I'll get to it during the week.

I took the path of least resistance and disabled the rule. But I share your sentiment. Pyright is easier to get along with.