minor improvements (#1330)

Signed-off-by: Michael Carlstrom <rmc@carlstrom.com>

rclpy/rclpy/client.py

@@ -41,7 +41,7 @@ def __init__(
         self,
         context: Context,
         client_impl: _rclpy.Client,
-        srv_type: Srv[SrvRequestT, SrvResponseT, SrvEventT],
+        srv_type: Type[Srv[SrvRequestT, SrvResponseT, SrvEventT]],
         srv_name: str,
         qos_profile: QoSProfile,
         callback_group: CallbackGroup
@@ -66,7 +66,7 @@ def __init__(
         self.srv_name = srv_name
         self.qos_profile = qos_profile
         # Key is a sequence number, value is an instance of a Future
-        self._pending_requests: Dict[int, Future] = {}
+        self._pending_requests: Dict[int, Future[SrvResponseT]] = {}
         self.callback_group = callback_group
         # True when the callback is ready to fire but has not been "taken" by an executor
         self._executor_event = False
@@ -95,7 +95,7 @@ def call(
 
         event = threading.Event()
 
-        def unblock(future):
+        def unblock(future: Future[SrvResponseT]) -> None:
             nonlocal event
             event.set()
 
@@ -109,11 +109,13 @@ def unblock(future):
             if not event.wait(timeout_sec):
                 # Timed out. remove_pending_request() to free resources
                 self.remove_pending_request(future)
-        if future.exception() is not None:
-            raise future.exception()
+
+        exception = future.exception()
+        if exception is not None:
+            raise exception
         return future.result()
 
-    def call_async(self, request: SrvRequestT) -> Future:
+    def call_async(self, request: SrvRequestT) -> Future[SrvResponseT]:
         """
         Make a service request and asynchronously get the result.
 
@@ -132,14 +134,14 @@ def call_async(self, request: SrvRequestT) -> Future:
             if sequence_number in self._pending_requests:
                 raise RuntimeError(f'Sequence ({sequence_number}) conflicts with pending request')
 
-            future = Future()
+            future = Future[SrvResponseT]()
             self._pending_requests[sequence_number] = future
 
             future.add_done_callback(self.remove_pending_request)
 
         return future
 
-    def get_pending_request(self, sequence_number: int) -> Future:
+    def get_pending_request(self, sequence_number: int) -> Future[SrvResponseT]:
         """
         Get a future from the list of pending requests.
 
@@ -150,7 +152,7 @@ def get_pending_request(self, sequence_number: int) -> Future:
         with self._lock:
             return self._pending_requests[sequence_number]
 
-    def remove_pending_request(self, future: Future) -> None:
+    def remove_pending_request(self, future: Future[SrvResponseT]) -> None:
         """
         Remove a future from the list of pending requests.
 
@@ -220,7 +222,7 @@ def service_name(self) -> str:
         with self.handle:
             return self.__client.service_name
 
-    def destroy(self):
+    def destroy(self) -> None:
         """
         Destroy a container for a ROS service client.
 
@@ -229,7 +231,7 @@ def destroy(self):
         """
         self.__client.destroy_when_not_in_use()
 
-    def __enter__(self) -> 'Client':
+    def __enter__(self) -> 'Client[SrvRequestT, SrvResponseT, SrvEventT]':
         return self
 
     def __exit__(

rclpy/rclpy/node.py

@@ -1677,7 +1677,7 @@ def create_subscription(
 
     def create_client(
         self,
-        srv_type: Srv[SrvRequestT, SrvResponseT, SrvEventT],
+        srv_type: Type[Srv[SrvRequestT, SrvResponseT, SrvEventT]],
         srv_name: str,
         *,
         qos_profile: QoSProfile = qos_profile_services_default,
@@ -1719,7 +1719,7 @@ def create_client(
 
     def create_service(
         self,
-        srv_type: Srv[SrvRequestT, SrvResponseT, SrvEventT],
+        srv_type: Type[Srv[SrvRequestT, SrvResponseT, SrvEventT]],
         srv_name: str,
         callback: Callable[[SrvRequestT, SrvResponseT], SrvResponseT],
         *,

rclpy/rclpy/service.py

@@ -36,7 +36,7 @@ class Service(Generic[SrvRequestT, SrvResponseT, SrvEventT]):
     def __init__(
         self,
         service_impl: _rclpy.Service,
-        srv_type: Srv[SrvRequestT, SrvResponseT, SrvEventT],
+        srv_type: Type[Srv[SrvRequestT, SrvResponseT, SrvEventT]],
         srv_name: str,
         callback: Callable[[SrvRequestT, SrvResponseT], SrvResponseT],
         callback_group: CallbackGroup,
@@ -112,7 +112,7 @@ def service_name(self) -> str:
         with self.handle:
             return self.__service.name
 
-    def destroy(self):
+    def destroy(self) -> None:
         """
         Destroy a container for a ROS service server.
 
@@ -121,7 +121,7 @@ def destroy(self):
         """
         self.__service.destroy_when_not_in_use()
 
-    def __enter__(self) -> 'Service':
+    def __enter__(self) -> 'Service[SrvRequestT, SrvResponseT, SrvEventT]':
         return self
 
     def __exit__(

rclpy/rclpy/type_support.py

@@ -66,8 +66,7 @@ class Srv(Protocol[SrvRequestT, SrvResponseT, SrvEventT], metaclass=CommonMsgSrv
     Response: Type[SrvResponseT]
     Event: Type[SrvEventT]
 
-    def __init__(self) -> NoReturn:
-        ...
+    def __init__(self) -> NoReturn: ...
 
 
 # Can be used if https://github.com/python/typing/issues/548 ever gets approved.