launch.actions.timer_action module

Module for the TimerAction action.

class launch.actions.timer_action.TimerAction

Bases: Action

Action that defers other entities until a period of time has passed, unless canceled.

All timers are “one-shot”, in that they only fire one time and never again.

Entities executed after the given period of time can access the launch configurations that exist at the time that the timer action executed, but changes made by them will not persist. This is similar to grouping the entities in a launch.actions.GroupAction with scoped=True.

__init__(*, period: float | str | Path | Substitution | Iterable[str | Path | Substitution], actions: Iterable[LaunchDescriptionEntity], cancel_on_shutdown: bool | str | Path | Substitution | Iterable[str | Path | Substitution] = True, **kwargs) → None

Create a TimerAction.

Parameters:

• period – the time (in seconds) to set the timer for

• actions – an iterable containing actions to be executed on timeout

• cancel_on_shutdown – whether to cancel the timer on launch shutdown

property actions

cancel() → None

Cancel this TimerAction.

Calling cancel will not fail if the timer has already finished or already been canceled or if the timer has not been started yet.

This function is not thread-safe and should be called only from under another coroutine.

describe() → str

Return a description of this TimerAction.

describe_conditional_sub_entities() → List[Tuple[str, Iterable[LaunchDescriptionEntity]]]

Return the actions that will result when the timer expires, but was not canceled.

execute(context: LaunchContext) → List[LaunchDescriptionEntity] | None

Execute the action.

This does the following: - register a global event handler for TimerAction’s if not already done - create a task for the coroutine that waits until canceled or timeout - coroutine asynchronously fires event after timeout, if not canceled

get_asyncio_future() → Future | None

Return an asyncio Future, used to let the launch system know when we’re done.

handle(context: LaunchContext) → LaunchDescriptionEntity | Iterable[LaunchDescriptionEntity] | None

Handle firing of timer.

classmethod parse(entity: Entity, parser: Parser)

Return the Timer action and kwargs for constructing it.

property period