Update link to VS Code formatting instructions (#3921)

[etc/vim.git] / src / blackd / middlewares.py

diff --git a/src/blackd/middlewares.py b/src/blackd/middlewares.py
index 7abde525bfdc0bf3297ac3bee67e08f284b59d18..370e0ae222eebfef1b73c185b4fc6130e87974cc 100644 (file)
--- a/src/blackd/middlewares.py
+++ b/src/blackd/middlewares.py
@@ -1,9 +1,19 @@
-from typing import Awaitable, Callable, Iterable
+from typing import TYPE_CHECKING, Any, Awaitable, Callable, Iterable, TypeVar
 
-from aiohttp.web_middlewares import middleware
 from aiohttp.web_request import Request
 from aiohttp.web_response import StreamResponse
 
+if TYPE_CHECKING:
+    F = TypeVar("F", bound=Callable[..., Any])
+    middleware: Callable[[F], F]
+else:
+    try:
+        from aiohttp.web_middlewares import middleware
+    except ImportError:
+        # @middleware is deprecated and its behaviour is the default since aiohttp 4.0
+        # so if it doesn't exist anymore, define a no-op for forward compatibility.
+        middleware = lambda x: x  # noqa: E731
+
 Handler = Callable[[Request], Awaitable[StreamResponse]]
 Middleware = Callable[[Request, Handler], Awaitable[StreamResponse]]
 
@@ -32,4 +42,4 @@ def cors(allow_headers: Iterable[str]) -> Middleware:
 
         return resp
 
-    return impl  # type: ignore
+    return impl