The case of multiple inheritance

[mehmetgiritli]

Hi,

I realised that it is not possible, as far as I can see, to inject a service which inherits multiple classes.

@abstract
class A(ABC):
...

@abstract
class B(ABC):
...

@service
class C(A, B):
...

As C implements both A and B, I expect instance of C to be injected when either A or B is requested:

@service
class Something:
    def __init__(c: Annotated[A, Inject()])
...

@service
class SomethingElse:
    def __init__(c: Annotated[B, Inject()])

However, this does not seem to work:

...
wireup.errors.UnknownQualifiedServiceRequestedError: Cannot instantiate concrete class for <class ....> as qualifier 'None' is unknown. Available qualifiers: [].

I'm not sure if this is me doing something wrong or if this is an enhancement.

[maldoinc]

The container only resolves the first parent class when registering a class. It should be possible to iterate over all bases and link all of them that are abstract with the current impl being registered. If you want to contribute that the relevant code is in ServiceRegistry.register_service method.

For the current version you can just register A and B as regular services via factories and have the factory request and inject C instead.

class A(ABC): ...


class B(ABC): ...


@service
class C(A, B): ...


@service
def a_factory(c: C) -> A:
    return c


@service
def b_factory(c: C) -> B:
    return c

[mehmetgiritli]

Thanks for the response.

I tried factory solution already but I get the same error. Then I realised that I still kept @ abstract on A and B. Removing @ abstract made it work. Just dropping the note here in case somebody else gets hit by it.

I'm hoping to contribute the feature soon with a PR.

Many thanks again.

[maldoinc]

Also FYI: In services you don't need to annotate dependencies with Annotated[T, Inject()]. That is only required in fastapi views due to how the framework is designed.