Function injection

In addition to constructor injection, diwire can inject dependencies into function parameters.

The building blocks are:

• diwire.Injected - a marker used inside typing.Annotated

• diwire.Container.resolve() - when given a function, returns an injected callable wrapper

Basic injection with Injected()

Mark injectable parameters using Annotated[T, Injected()]. All other parameters remain caller-provided.

See the runnable scripts in Function injection (Injected marker section).

Per-call scopes for request handlers

If your function needs scoped services (for example a request-scoped DB session), resolve the function with a scope:

See the runnable scripts in Function injection (Per-call scope section).

Decorator style

You can also use resolve() as a decorator:

from typing import Annotated
from diwire import Container, Injected

container = Container()


@container.resolve()
def handler(service: Annotated["Service", Injected()]) -> str:
    return service.run()

For framework integration (FastAPI/Starlette), also see container_context and FastAPI.