@app.exception_handler(UnicornException)
async def unicorn_exception_handler(request: Request, exc: UnicornException):
    return JSONResponse(
        status_code=418,
        content={"message": f"Oops! {exc.name} did something. There goes a rainbow..."},
    )


@app.get("/unicorns/{name}")
async def read_unicorn(name: str):
    if name == "yolo":
        raise UnicornException(name=name)

到目前为止，您看到的依赖项都被声明为函数。

但这并不是声明依赖项的唯一方法(尽管它可能是更常见的方法)。

关键因素是依赖项应该是 "可调用对象"。

Python 中的 "**可调用对象**" 是指任何 Python 可以像函数一样 "调用" 的对象。

所以，如果你有一个对象 `something` (可能*不是*一个函数)，你可以 "调用" 它(执行它)，就像：

```Python
something()
```

或者

```Python
something(some_argument, some_keyword_argument="foo")
```

这就是 "可调用对象"。

## 类作为依赖项

您可能会注意到，要创建一个 Python 类的实例，您可以使用相同的语法。

举个例子:

```Python

def test_get_exception():
    response = client.get("/unicorns/yolo")
    assert response.status_code == 418, response.text
    assert response.json() == {
        "message": "Oops! yolo did something. There goes a rainbow..."
    }


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {

	netns io.Closer
	fd    uintptr
	inode uint64
}

func (n *NetnsWithFd) Close() error {
	if n.netns == nil {
		return nil
	}

	ret := n.netns.Close()
	// set fd to invalid value, so if something uses it by mistake it will err
	uintZero := uintptr(0)
	n.fd = ^uintZero
	return ret
}

func (n *NetnsWithFd) Fd() uintptr {
	return n.fd
}

func (n *NetnsWithFd) Inode() uint64 {
	return n.inode

A "**callable**" in Python is anything that Python can "call" like a function.

So, if you have an object `something` (that might _not_ be a function) and you can "call" it (execute it) like:

```Python
something()
```

or

```Python
something(some_argument, some_keyword_argument="foo")
```

then it is a "callable".

## Classes as dependencies

	return Pair[T1, T2]{f1: v1, f2: v2}
}

func (p Pair[X1, _]) First() X1 {
	return p.f1
}

func (p Pair[_, X2]) Second() X2 {
	return p.f2
}

// Deprecated: Use something else.
func Clone[S ~[]T, T any](s S) S {
	return append(S(nil), s...)

 * literal code</pre> does something.
<p>another para.
<ul><li>item1</li></ul>
'''

        when:
        def result = parser.parse(classMetaData, listener)

        then:
        format(result.docbook) == '''<para>for example: </para><programlisting language="java">this is some
literal code</programlisting><para> does something.
</para><para>another para.

`Optional[Something]` মূলত `Union[Something, None]`-এর একটি শর্টকাট, এবং তারা সমতুল্য।

এর মানে হল, Python 3.10-এ, আপনি টাইপগুলির ইউনিয়ন ঘোষণা করতে `Something | None` ব্যবহার করতে পারেন:

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

    "servers": [
        {
            "url": "/api/v1"
        }
    ],
    "paths": {
            // More stuff here
    }
}
```

In this example, the "Proxy" could be something like **Traefik**. And the server would be something like FastAPI CLI with **Uvicorn**, running your FastAPI application.

### Providing the `root_path`

To achieve this, you can use the command line option `--root-path` like:

<div class="termy">

FROM ubuntu:noble

ENV DEBIAN_FRONTEND=noninteractive

# Do not add more stuff to this list that isn't small or critically useful.
# If you occasionally need something on the container do
# sudo apt-get update && apt-get whichever

# hadolint ignore=DL3005,DL3008
RUN apt-get update && \
  apt-get install --no-install-recommends -y \
  ca-certificates \
  curl \
  iptables \
  iproute2 \
  iputils-ping \
  knot-dnsutils \