def execute(self, context: launch.LaunchContext) -> Optional[List[Action]]:
"""
Execute the action.
Delegated to :meth:`launch.actions.ExecuteProcess.execute`.
"""
# self._perform_substitutions(context) # ensure self.node_name is expanded
if '<node_name_unspecified>' in self.node_name:
raise RuntimeError(
'node_name unexpectedly incomplete for system_modes node')
node = get_ros_node(context)
# Create a subscription to monitor the mode changes of the subprocess.
self.__rclpy_mode_subscription = node.create_subscription(
system_modes_msgs.msg.ModeEvent,
'{}/mode_event'.format(self.node_name),
functools.partial(self._on_mode_event, context), 10)
# Create a subscription to monitor the state changes of the subprocess.
self.__rclpy_state_subscription = node.create_subscription(
lifecycle_msgs.msg.TransitionEvent,
'{}/transition_event'.format(self.node_name),
functools.partial(self._on_state_event, context), 10)
# Create a service client to change mode on demand.
self.__rclpy_change_mode_client = node.create_client(
system_modes_msgs.srv.ChangeMode,
'{}/change_mode'.format(self.node_name))
# Create a service client to change state on demand.
self.__rclpy_change_state_client = node.create_client(
lifecycle_msgs.srv.ChangeState,
'{}/change_state'.format(self.node_name))
# Register an event handler to change modes on a ChangeMode system_modes event.
context.register_event_handler(
launch.EventHandler(
matcher=lambda event: isinstance(event, ChangeMode),
entities=[
launch.actions.OpaqueFunction(
function=self._on_change_mode_event)
],
))
# Register an event handler to change states on a ChangeState event.
context.register_event_handler(
launch.EventHandler(
matcher=lambda event: isinstance(event, ChangeState),
entities=[
launch.actions.OpaqueFunction(
function=self._on_change_state_event)
],
))
# Delegate execution to ExecuteProcess.
return super().execute(context)
def get_default_launch_description(*, prefix_output_with_name=False):
"""
Return a LaunchDescription to be included before user descriptions.
:param: prefix_output_with_name if True, each line of output is prefixed
with the name of the process as `[process_name] `, else it is printed
unmodified
"""
default_ros_launch_description = launch.LaunchDescription([
# ROS initialization (create node and other stuff).
ROSSpecificLaunchStartup(),
# Handle process starts.
launch.actions.RegisterEventHandler(
launch.EventHandler(
matcher=lambda event: isinstance(
event, launch.events.process.ProcessStarted),
entities=[
launch.actions.OpaqueFunction(function=_on_process_started)
],
)),
# Handle process exit.
launch.actions.RegisterEventHandler(
launch.EventHandler(
matcher=lambda event: isinstance(
event, launch.events.process.ProcessExited),
entities=[
launch.actions.OpaqueFunction(function=_on_process_exited)
],
)),
# Add default handler for output from processes.
launch.actions.RegisterEventHandler(
launch.event_handlers.OnProcessIO(
on_stdout=functools.partial(
_on_process_output,
file_name='stdout',
prefix_output=prefix_output_with_name),
on_stderr=functools.partial(
_on_process_output,
file_name='stderr',
prefix_output=prefix_output_with_name),
)),
])
return default_ros_launch_description