aiohttp handler decorator type hints

aiohttp_handler_decorator_type_hints.md

from collections.abc import Awaitable, Callable
from functools import wraps
from typing import Concatenate, ParamSpec, TypeVar

from aiohttp import web

Params = ParamSpec("Params")
Request = TypeVar("Request", bound=web.Request)
Response = TypeVar("Response", bound=web.StreamResponse)
Handler = Callable[Concatenate[Request, Params], Awaitable[Response]]


# TODO: заменить типизацию во всех wrapper c `web.Request` на `Request`
#  после закрытия дефекта: https://youtrack.jetbrains.com/issue/PY-66446


def some_decorator(handler: Handler) -> Handler:
    """Какой-то декоратор."""

    @wraps(handler)
    async def wrapper(
        request: web.Request,
        *args: Params.args,
        **kwargs: Params.kwargs,
    ) -> Response:
        # do something before

        result = await handler(request, *args, **kwargs)

        # do something after

        return result

    return wrapper


@some_decorator
async def echo_handler(request: Request) -> Response:
    echo = await request.text()
    return web.Response(text=echo)