Modify @cache_in_self decorator to accept self classes other than HomeServer

We want to use this in conjunction with ModuleApi in order to save and
reference singleton instances of module api callback classes.

1 files changed, 5 insertions, 3 deletions

diff --git a/synapse/util/caches/cache_in_self_decorator.py b/synapse/util/caches/cache_in_self_decorator.py

index fea41b9d08..3b9ded2096 100644
--- a/synapse/util/caches/cache_in_self_decorator.py
+++ b/synapse/util/caches/cache_in_self_decorator.py
@@ -1,9 +1,11 @@
-from typing import TYPE_CHECKING, Callable, Dict, List, Optional, TypeVar, cast
+import functools
+from typing import Callable, TypeVar
 
 T = TypeVar("T")
+U = TypeVar("U")
 
 
-def cache_in_self(builder: Callable[["HomeServer"], T]) -> Callable[["HomeServer"], T]:
+def cache_in_self(builder: Callable[[T], U]) -> Callable[[T], U]:
     """Wraps a function called e.g. `get_foo`, checking if `self.foo` exists and
     returning if so. If not, calls the given function and sets `self.foo` to it.
 
@@ -22,7 +24,7 @@ def cache_in_self(builder: Callable[["HomeServer"], T]) -> Callable[["HomeServer
     building = [False]
 
     @functools.wraps(builder)
-    def _get(self: "HomeServer") -> T:
+    def _get(self: T) -> U:
         try:
             return getattr(self, depname)
         except AttributeError: