Automatically use context managers as context dependency definition

[g0di]

In order to add cleanup to a dependency in a container we have to register it using context_dependency_definition decorator and use the try: yield ... finally: cleanup pattern.

I'm wondering if this could be avoided for objects already defined as context manager and providing __enter__ and __exit__ functions. For example

# Note that Contextual is just an idea
from lagom import Container,  Contextual, context_dependency_definition

class MyService:
    def __enter__(self):
        return self

    def __exit__(self): 
        print("cleanup!")

container =  Container()

container[MyDep] = Contextual(MyDep)
# Or
@context_dependency_definition(container)
def _make_my_dep() -> MyDep:
    return MyDep()

IMO this could make it easier to record dependencies that are contextual and requires some cleanup

[g0di]

For anyone looking for an answer, I found it myself by looking at the source code. You can simply do the following:

from typing import ContextManager

container[ContextManager[MyDep]] = MyDep

Maybe this could be added to the documentation

As a side note I'm wondering if it would not be better to mark a dependency as using context manager through a lagom class like Singleton? container[MyDep] = lagom.ContextManager(MyDep) because using a context make me thing of a lifetime. It means that this dependency requires a context to be actually resolved.