Add Const injector

rollbot/rollbot/injection/util.py

@@ -27,6 +27,7 @@ __all__ = [
     "Debugging",
     "Config",
     "Lazy",
+    "Const",
 ]
 
 MessageInjector = Simple[Message](lambda m, c: m)
@@ -46,7 +47,6 @@ Respond = Simple[Callable[[], Coroutine[None, None, None]]](lambda m, c: c.respo
 LoggerInjector = Simple[Logger](lambda m, c: c.logger)
 Debugging = Simple[Optional[str]](lambda m, c: c.get_debugging())
 
-
 class Config(Injector[Any]):
     def __init__(self, key: str):
         self.key = key
@@ -84,3 +84,10 @@ class Lazy(InjectorWithCleanup[Callable[[], Coroutine[None, None, Dep]]]):
     async def cleanup(self, dep: Callable[[], Coroutine[None, None, Dep]]):
         if isinstance(self.deferred, InjectorWithCleanup) and dep._calculated is not None:
             await self.deferred.cleanup(dep._calculated)
+
+class Const(Injector[Dep]):
+    def __init__(self, const: Dep):
+        self.const = const
+
+    async def inject(self, message: Message, context: Context) -> Dep:
+        return self.const