Type hinting __aenter__ with Self (#367)

* Added typing-extensions to dependencies for Python<=3.10

* Moved to using Self type for CachedSession.__aenter__

* Moved to using Self type for CachedResponse.__aenter__

Author: jamesbraza

aiohttp_client_cache/response.py

@@ -4,6 +4,7 @@
 
 import asyncio
 import json
+import sys
 from collections.abc import Mapping
 from datetime import datetime
 from functools import singledispatch
@@ -23,6 +24,11 @@
 
 from aiohttp_client_cache.cache_control import utcnow
 
+if sys.version_info >= (3, 11):
+    from typing import Self
+else:
+    from typing_extensions import Self
+
 # CachedResponse attributes to not copy directly from ClientResponse
 EXCLUDE_ATTRS = {
     '_body',
@@ -259,7 +265,7 @@ def _released(self):
     def connection(self):
         return None
 
-    async def __aenter__(self) -> CachedResponse:
+    async def __aenter__(self) -> Self:
         return self
 
     async def __aexit__(self, *exc: Any) -> None:

aiohttp_client_cache/session.py

@@ -42,6 +42,12 @@ async def __aexit__(self, *excinfo):
             pass
 
 
+if sys.version_info >= (3, 11):
+    from typing import Self
+else:
+    from typing_extensions import Self
+
+
 @lru_cache(maxsize=16384)
 def _get_lock(_: int, __: str) -> Lock:
     return Lock()
@@ -245,5 +251,5 @@ class CachedSession(CacheMixin, ClientSession):
                 options. If not provided, an in-memory cache will be used.
         """
 
-        async def __aenter__(self) -> CachedSession:
+        async def __aenter__(self) -> Self:
             return self

poetry.lock

@@ -34,6 +34,7 @@ python          = ">=3.9"
 aiohttp         = "^3.8"
 attrs           = ">=21.2"
 itsdangerous    = ">=2.0"
+typing-extensions = {python="<=3.10", version=">=4"}  # Pin v4 for Self addition
 url-normalize   = "^2.2"
 
 # Optional backend dependencies