Should the class based dependency injection docs be updated to more accurately reflect what you can do?

[Jay-Madden]

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Example Code

# Domain module
from typing import Annotated

from fastapi import Depends


class SubDep:
    def __init__(self):
        print('SubDep ctor')
        pass

    def foo(self):
        return 'hi'


class Example:
    def __init__(self, sub_dep: Annotated[SubDep, Depends()]):
        print('Example ctor')
        self.sub_dep = sub_dep


# Path operation
@app.get("/")
async def change_me(example: Annotated[Example, Depends()]):
    return JSONResponse(content={"id": example.sub_dep.foo()})

Description

I believe the classes as dependencies docs page https://fastapi.tiangolo.com/tutorial/dependencies/classes-as-dependencies/ is incredibly unclear and confusing. It fails to explain that actual point of class based dependency injection. And does not show examples of this pattern actually being used with annotated in the constructors etc.

As shown in the example code the DI system is incredibly powerful and lets you write significantly more scalable code easily. I think the docs could be updated to more accurately advertise this incredible feature.

Operating System

Linux, Windows, macOS, Other

Operating System Details

No response

FastAPI Version

Latest

Python Version

3.10

Additional Context

I would be willing to take on the requirement of updating this docs page should it be deemed a good contribution.