Add types to time_source.py (#1259)

* Add types to time_source.py

Signed-off-by: Michael Carlstrom <[email protected]>

rclpy/rclpy/time_source.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import List, Optional, Set, TYPE_CHECKING
 import weakref
 
 from rcl_interfaces.msg import SetParametersResult
@@ -23,28 +24,32 @@
 from rclpy.time import Time
 import rosgraph_msgs.msg
 
+if TYPE_CHECKING:
+    from rclpy.node import Node
+    from rclpy.subscription import Subscription
+
 CLOCK_TOPIC = '/clock'
 USE_SIM_TIME_NAME = 'use_sim_time'
 
 
 class TimeSource:
 
-    def __init__(self, *, node=None):
-        self._clock_sub = None
-        self._node_weak_ref = None
-        self._associated_clocks = set()
+    def __init__(self, *, node: Optional['Node'] = None):
+        self._clock_sub: Optional['Subscription'] = None
+        self._node_weak_ref: Optional[weakref.ReferenceType['Node']] = None
+        self._associated_clocks: Set[ROSClock] = set()
         # Zero time is a special value that means time is uninitialzied
         self._last_time_set = Time(clock_type=ClockType.ROS_TIME)
         self._ros_time_is_active = False
         if node is not None:
             self.attach_node(node)
 
     @property
-    def ros_time_is_active(self):
+    def ros_time_is_active(self) -> bool:
         return self._ros_time_is_active
 
     @ros_time_is_active.setter
-    def ros_time_is_active(self, enabled):
+    def ros_time_is_active(self, enabled: bool) -> None:
         if self._ros_time_is_active == enabled:
             return
         self._ros_time_is_active = enabled
@@ -59,7 +64,7 @@ def ros_time_is_active(self, enabled):
                     node.destroy_subscription(self._clock_sub)
                     self._clock_sub = None
 
-    def _subscribe_to_clock_topic(self):
+    def _subscribe_to_clock_topic(self) -> None:
         if self._clock_sub is None:
             node = self._get_node()
             if node is not None:
@@ -70,7 +75,7 @@ def _subscribe_to_clock_topic(self):
                     QoSProfile(depth=1, reliability=ReliabilityPolicy.BEST_EFFORT)
                 )
 
-    def attach_node(self, node):
+    def attach_node(self, node: 'Node') -> None:
         from rclpy.node import Node
         if not isinstance(node, Node):
             raise TypeError('Node must be of type rclpy.node.Node')
@@ -97,7 +102,7 @@ def attach_node(self, node):
 
         node.add_on_set_parameters_callback(self._on_parameter_event)
 
-    def detach_node(self):
+    def detach_node(self) -> None:
         # Remove the subscription to the clock topic.
         if self._clock_sub is not None:
             node = self._get_node()
@@ -107,22 +112,22 @@ def detach_node(self):
         self._clock_sub = None
         self._node_weak_ref = None
 
-    def attach_clock(self, clock):
+    def attach_clock(self, clock: ROSClock) -> None:
         if not isinstance(clock, ROSClock):
             raise ValueError('Only clocks with type ROS_TIME can be attached.')
 
         clock.set_ros_time_override(self._last_time_set)
         clock._set_ros_time_is_active(self.ros_time_is_active)
         self._associated_clocks.add(clock)
 
-    def clock_callback(self, msg):
+    def clock_callback(self, msg: rosgraph_msgs.msg.Clock) -> None:
         # Cache the last message in case a new clock is attached.
         time_from_msg = Time.from_msg(msg.clock)
         self._last_time_set = time_from_msg
         for clock in self._associated_clocks:
             clock.set_ros_time_override(time_from_msg)
 
-    def _on_parameter_event(self, parameter_list):
+    def _on_parameter_event(self, parameter_list: List[Parameter]) -> SetParametersResult:
         successful = True
         reason = ''
 
@@ -142,7 +147,7 @@ def _on_parameter_event(self, parameter_list):
 
         return SetParametersResult(successful=successful, reason=reason)
 
-    def _get_node(self):
+    def _get_node(self) -> Optional['Node']:
         if self._node_weak_ref is not None:
             return self._node_weak_ref()
         return None