Add Starlette lifespan handler implementation

[ZipFile]

Starlette recently added cool new feature called lifespan in v0.26.0 and FastAPI followed the suit in v0.93.0. This makes it possible to get rid of good chunk of initialization spaghetti in starlette-based apps (making container a single entry point in the application), + reduces amount of the pain in the ass scheduling background tasks in the event loop of the ASGI app.

Example

myapp/container.py

from dependency_injector.containers import DeclarativeContainer
from dependency_injector.ext.starlette import Lifespan
from dependency_injector.providers import Factory, Resource, Self, Singleton
from fastapi import FastAPI


def init():
  print("Inittializing resources")
  yield
  print("Cleaning up resources")


class Container(DeclarativeContainer):
    __self__ = Self()
    lifespan = Singleton(Lifespan, __self__)
    app = Factory(FastAPI, lifespan=lifespan)
    init = Resource(init)

myapp/asgi.py:

from .container import Container

container = Container()
app = container.app()

run.sh:

uvicorn myapp.asgi:app

[ZipFile]

Looks like project is still alive. Rebased with latest master.

[nightblure]

Hi!
Thanks for the nice change. Perhaps it would be appropriate to add an explicit return None at the end of __aenter__

[ZipFile]

You generally want explicit return None at the end if you returned something earlier in the function. There are no returns at all here, so this is extra.

[nightblure]

Here you need to change the return type probably to Optional[Awaitable]

[ZipFile]

1. This method will be inferred as def __aenter__(self) -> Awaitable[None]:
2. -> Optional[Awaitable] means function returns either None or something that you can await (e.g. signature of the init_resources). Given the pt.1, annotating it with your suggestion will result in Awaitable[Optional[Awaitable]], which does not conforms to StatelessLifespan protocol.