Merge pull request #30 from Zuehlke/feature/async-decorator

Feature/async decorator

confz/change.py

@@ -54,9 +54,17 @@ def __init__(self, fn: Callable[[], Any], config_classes: List[Type['ConfZ']]):
         self._backup_instances = {}
 
     def __call__(self):
-        if self._instance is None:
-            self._instance = self._fn()
-        return self._instance
+        if inspect.iscoroutinefunction(self._fn):
+            async def inner():
+                if self._instance is None:
+                    self._instance = await self._fn()
+                return self._instance
+        else:
+            def inner():
+                if self._instance is None:
+                    self._instance = self._fn()
+                return self._instance
+        return inner()
 
     def change_enter(self, context):
         self._backup_instances[context] = self._instance

docs/source/usage/listeners.rst

@@ -35,6 +35,21 @@ changed because we are in a config change context manager and the function gets
 allowing the new config to take effect. As soon as the context is left again, the original instance of the function
 singleton will be active again.
 
+This decorator also works for asynchronous functions::
+
+    from confz import depends_on
+
+    @depends_on(DBConfig)
+    async def get_engine():
+        engine = create_async_engine(f'sqlite:///{DBConfig().path}', echo=True)
+
+        async with engine.begin() as conn:
+            await conn.run_sync(meta.drop_all)
+            await conn.run_sync(meta.create_all)
+
+        return engine
+
+
 Early Loading
 -------------