fix(typing): explicit handler signatures in PubSubClient

CHANGELOG.md

@@ -18,6 +18,7 @@
 ### Bug fixes
 
 * Fix `flet build` failing on Windows when a dependency is pulled in via `[tool.flet.<platform>].dev_packages` (or any local-path install): the rewritten `<pkg> @ file://<path>` URL now uses `Path.as_uri()`, producing the correct `file:///D:/...` three-slash form instead of `file://D:\...`, which pip on Windows parsed as a UNC path and aborted with `OSError: [Errno 2] No such file or directory: '\\\\D:\\a\\...'` ([#6577](https://github.com/flet-dev/flet/pull/6577)) by @FeodorFitsner.
+* Specify `handler` signatures in `subscribe` and `subscribe_topic` methods of `PubSubClient` for better type checking ([#6549](https://github.com/flet-dev/flet/pull/6564)) by @Iaw4tch
 
 ## 0.85.3
 

sdk/python/packages/flet/src/flet/pubsub/pubsub_client.py

@@ -57,7 +57,7 @@ def send_others_on_topic(self, topic: str, message: Any):
         """
         self.__pubsub.send_others_on_topic(self.__session_id, topic, message)
 
-    def subscribe(self, handler: Callable):
+    def subscribe(self, handler: Callable[[Any], Any]):
         """
         Subscribes this session to global messages.
 
@@ -68,7 +68,7 @@ def subscribe(self, handler: Callable):
         """
         self.__pubsub.subscribe(self.__session_id, handler)
 
-    def subscribe_topic(self, topic: str, handler: Callable):
+    def subscribe_topic(self, topic: str, handler: Callable[[str, Any], Any]):
         """
         Subscribes this session to a topic.