CommandScheduler

class commands2.CommandScheduler

Bases: Sendable

The scheduler responsible for running Commands. A Command-based robot should call run() on the singleton instance in its periodic block in order to run commands synchronously from the main loop. Subsystems should be registered with the scheduler using registerSubsystem() in order for their commands2.Subsystem.periodic() methods to be called and for their default commands to be scheduled.

Gets the scheduler instance.

cancel(*commands: Command) → None

Cancels commands. The scheduler will only call commands2.Command.end() method of the canceled command with True, indicating they were canceled (as opposed to finishing normally).

Commands will be canceled regardless of InterruptionBehavior interruption behavior.

Parameters:

commands – the commands to cancel

cancelAll() → None

Cancels all commands that are currently scheduled.

clearComposedCommands() → None

Clears the list of composed commands, allowing all commands to be freely used again.

Warning

Using this haphazardly can result in unexpected/undesirable behavior. Do not use this unless you fully understand what you are doing.

disable() → None

Disables the command scheduler.

enable() → None

Enables the command scheduler.

getActiveButtonLoop() → EventLoop

Get the active button poll.

Returns:

a reference to the current EventLoop object polling buttons.

getDefaultButtonLoop() → EventLoop

Get the default button poll.

Returns:

a reference to the default EventLoop object polling buttons.

getDefaultCommand(subsystem: Subsystem) → Command | None

Gets the default command associated with this subsystem. Null if this subsystem has no default command associated with it.

Parameters:

subsystem – the subsystem to inquire about

Returns:

the default command associated with the subsystem

static getInstance() → CommandScheduler

Returns the Scheduler instance.

Returns:

the instance

initSendable(builder: wpiutil._wpiutil.SendableBuilder) → None

Initializes this Sendable object.

Parameters:

builder – sendable builder

isComposed(command: Command) → bool

Check if the given command has been composed.

Parameters:

command – The command to check

Returns:

true if composed

isScheduled(*commands: Command) → bool

Whether the given commands are running. Note that this only works on commands that are directly scheduled by the scheduler; it will not work on commands inside compositions, as the scheduler does not see them.

Parameters:

commands – the command to query

Returns:

whether the command is currently scheduled

onCommandExecute(action: Callable[[Command], Any]) → None

Adds an action to perform on the execution of any command by the scheduler.

Parameters:

action – the action to perform

onCommandFinish(action: Callable[[Command], Any]) → None

Adds an action to perform on the finishing of any command by the scheduler.

Parameters:

action – the action to perform

onCommandInitialize(action: Callable[[Command], Any]) → None

Adds an action to perform on the initialization of any command by the scheduler.

Parameters:

action – the action to perform

onCommandInterrupt(action: Callable[[Command], Any]) → None

Adds an action to perform on the interruption of any command by the scheduler.

Parameters:

action – the action to perform

onCommandInterruptWithCause(action: Callable[[Command, Command | None], Any]) → None

Adds an action to perform on the interruption of any command by the scheduler. The action receives the interrupted command and the command that interrupted it

Parameters:

action – the action to perform

registerComposedCommands(commands: Iterable[Command]) → None

Register commands as composed. An exception will be thrown if these commands are scheduled directly or added to a composition.

Parameters:

commands – the commands to register

Raises:

IllegalCommandUse – if the given commands have already been composed.

registerSubsystem(*subsystems: Subsystem) → None

Registers subsystems with the scheduler. This must be called for the subsystem’s periodic block to run when the scheduler is run, and for the subsystem’s default command to be scheduled. It is recommended to call this from the constructor of your subsystem implementations.

Parameters:

subsystems – the subsystem to register

removeComposedCommand(command: Command) → None

Removes a single command from the list of composed commands, allowing it to be freely used again.

Warning

Using this haphazardly can result in unexpected/undesirable behavior. Do not use this unless you fully understand what you are doing.

Parameters:

command – the command to remove from the list of grouped commands

removeDefaultCommand(subsystem: Subsystem) → None

Removes the default command for a subsystem. The current default command will run until another command is scheduled that requires the subsystem, at which point the current default command will not be re-scheduled.

Parameters:

subsystem – the subsystem whose default command will be removed

requireNotComposed(*commands: Command) → None

Requires that the specified command hasn’t been already added to a composition.

Parameters:

commands – The commands to check

Raises:

IllegalCommandUse – if the given commands have already been composed.

requireNotComposedOrScheduled(*commands: Command) → None

Requires that the specified command hasn’t already been added to a composition, and is not currently scheduled.

Parameters:

command – The command to check

Raises:

IllegalCommandUse – if the given command has already been composed or scheduled.

requiring(subsystem: Subsystem) → Command | None

Returns the command currently requiring a given subsystem. None if no command is currently requiring the subsystem

Parameters:

subsystem – the subsystem to be inquired about

Returns:

the command currently requiring the subsystem, or None if no command is currently scheduled

static resetInstance() → None

Resets the scheduler instance, which is useful for testing purposes. This should not be called by user code.

run() → None

Runs a single iteration of the scheduler. The execution occurs in the following order:

• Subsystem periodic methods are called.

• Button bindings are polled, and new commands are scheduled from them.

• Currently-scheduled commands are executed.

• End conditions are checked on currently-scheduled commands, and commands that are finished have their end methods called and are removed.

• Any subsystems not being used as requirements have their default methods started.

schedule(*commands: Command) → None

Schedules a command for execution. Does nothing if the command is already scheduled. If a command’s requirements are not available, it will only be started if all the commands currently using those requirements have been scheduled as interruptible. If this is the case, they will be interrupted and the command will be scheduled.

Parameters:

commands – the commands to schedule.

setActiveButtonLoop(loop: EventLoop) → None

Replace the button poll with another one.

Parameters:

loop – the new button polling loop object.

setDefaultCommand(subsystem: Subsystem, defaultCommand: Command) → None

Sets the default command for a subsystem. Registers that subsystem if it is not already registered. Default commands will run whenever there is no other command currently scheduled that requires the subsystem. Default commands should be written to never end (i.e. their commands2.Command.isFinished() method should return False), as they would simply be re-scheduled if they do. Default commands must also require their subsystem.

Parameters:

• subsystem – the subsystem whose default command will be set

• defaultCommand – the default command to associate with the subsystem

setPeriod(period: float) → None

Changes the period of the loop overrun watchdog. This should be kept in sync with the TimedRobot period.

Parameters:

period – Period in seconds.

unregisterAllSubsystems()

Un-registers all registered Subsystems with the scheduler. All currently registered subsystems will no longer have their periodic block called, and will not have their default command scheduled.

unregisterSubsystem(*subsystems: Subsystem) → None

Un-registers subsystems with the scheduler. The subsystem will no longer have its periodic block called, and will not have its default command scheduled.

Parameters:

subsystems – the subsystem to un-register