/**
     * {@return the root directory where the sources are stored}
     * The path is relative to the <abbr>POM</abbr> file.
     *
     * <h4>Default implementation</h4>
     * The default value depends on whether a {@linkplain #module() module name} is specified in this source root:
     * <ul>
     *   <li>
     *     If no module name, then the default directory is

O **FastAPI** garantirá que o "código de saída" em cada dependência com `yield` é executado na ordem correta.

Por exemplo, `dependency_c` pode depender de `dependency_b`, e `dependency_b` depender de `dependency_a`:

{* ../../docs_src/dependencies/tutorial008_an_py39.py hl[6,14,22] *}

E todas elas podem utilizar `yield`.

At some point, you will probably end up writing many different programs that depend on **different packages**. And some of these projects you work on will depend on **different versions** of the same package. 😱

For example, you could create a project called `philosophers-stone`, this program depends on another package called **`harry`, using the version `1`**. So, you need to install `harry`.

```mermaid

@app.get("/wrapped-dependency/")
async def get_wrapped_dependency(value: bool = Depends(wrapped_dependency)):
    return value


@app.get("/wrapped-gen-dependency/")
async def get_wrapped_gen_dependency(value: bool = Depends(wrapped_gen_dependency)):
    return value


@app.get("/async-wrapped-dependency/")
async def get_async_wrapped_dependency(value: bool = Depends(async_wrapped_dependency)):
    return value

async def get_partial_function_dependency(
    value: Annotated[
        str, Depends(partial(function_dependency, "partial-function-dependency"))
    ],
) -> str:
    return value


@app.get("/partial-async-function-dependency")
async def get_partial_async_function_dependency(
    value: Annotated[
        str,
        Depends(
            partial(async_function_dependency, "partial-async-function-dependency")
        ),

## Аннотация типа и `Depends` { #type-annotation-vs-depends }

Обратите внимание, что в приведенном выше коде мы два раза пишем `CommonQueryParams`:

//// tab | Python 3.9+

```Python
commons: Annotated[CommonQueryParams, Depends(CommonQueryParams)]
```

////

//// tab | Python 3.9+ non-Annotated

/// tip | Подсказка

## Anotación de tipos vs `Depends` { #type-annotation-vs-depends }

Nota cómo escribimos `CommonQueryParams` dos veces en el código anterior:

//// tab | Python 3.9+

```Python
commons: Annotated[CommonQueryParams, Depends(CommonQueryParams)]
```

////

//// tab | Python 3.9+ sin `Annotated`

/// tip | Consejo

@app.get("/decorator-depends/", dependencies=[Depends(common_parameters)])
async def decorator_depends():
    return {"in": "decorator-depends"}


@router.get("/router-depends/")
async def router_depends(commons: dict = Depends(common_parameters)):
    return {"in": "router-depends", "params": commons}


@router.get("/router-decorator-depends/", dependencies=[Depends(common_parameters)])
async def router_decorator_depends():

):
    return await instance(value)


@app.get("/async-callable-gen-dependency-class")
async def get_async_callable_gen_dependency_class(
    value: str, instance: AsyncCallableGenDependency = Depends()
):
    return await instance(value).__anext__()


@app.get("/callable-dependency")
async def get_callable_dependency(value: str = Depends(callable_dependency)):
    return value

# Histoire, conception et avenir

Il y a quelque temps, <a href="https://github.com/fastapi/fastapi/issues/3#issuecomment-454956920" class="external-link" target="_blank">un utilisateur de **FastAPI** a demandé</a> :

> Quelle est l'histoire de ce projet ? Il semble être sorti de nulle part et est devenu génial en quelques semaines [...].

Voici un petit bout de cette histoire.

## Alternatives