Command

class wpilib.command.Command(*args, **kwargs)

Bases: wpilib._wpilib.ErrorBase, wpilib._wpilib.Sendable

The Command class is at the very core of the entire command framework.

Every command can be started with a call to Start(). Once a command is started it will call Initialize(), and then will repeatedly call Execute() until the IsFinished() returns true. Once it does,End() will be called.

However, if at any point while it is running Cancel() is called, then the command will be stopped and Interrupted() will be called.

If a command uses a Subsystem, then it should specify that it does so by calling the Requires() method in its constructor. Note that a Command may have multiple requirements, and Requires() should be called for each one.

If a command is running and a new command with shared requirements is started, then one of two things will happen. If the active command is interruptible, then Cancel() will be called and the command will be removed to make way for the new one. If the active command is not interruptible, the other one will not even be started, and the active one will continue functioning.

@see CommandGroup @see Subsystem

Overloaded function.

  1. __init__(self: wpilib.command._commands_v1.Command) -> None

Creates a new command.

The name of this command will be default.

  1. __init__(self: wpilib.command._commands_v1.Command, name: str) -> None

Creates a new command with the given name and no timeout.

Parameters:name – the name for this command
  1. __init__(self: wpilib.command._commands_v1.Command, timeout: float) -> None

Creates a new command with the given timeout and a default name.

Parameters:timeout – the time (in seconds) before this command “times out” @see IsTimedOut()
  1. __init__(self: wpilib.command._commands_v1.Command, subsystem: frc::Subsystem) -> None

Creates a new command with the given timeout and a default name.

Parameters:subsystem – the subsystem that the command requires
  1. __init__(self: wpilib.command._commands_v1.Command, name: str, timeout: float) -> None

Creates a new command with the given name and timeout.

Parameters:
  • name – the name of the command
  • timeout – the time (in seconds) before this command “times out” @see IsTimedOut()
  1. __init__(self: wpilib.command._commands_v1.Command, name: str, subsystem: frc::Subsystem) -> None

Creates a new command with the given name and timeout.

Parameters:
  • name – the name of the command
  • subsystem – the subsystem that the command requires
  1. __init__(self: wpilib.command._commands_v1.Command, timeout: float, subsystem: frc::Subsystem) -> None

Creates a new command with the given name and timeout.

Parameters:
  • timeout – the time (in seconds) before this command “times out”
  • subsystem – the subsystem that the command requires @see IsTimedOut()
  1. __init__(self: wpilib.command._commands_v1.Command, name: str, timeout: float, subsystem: frc::Subsystem) -> None

Creates a new command with the given name and timeout.

Parameters:
  • name – the name of the command
  • timeout – the time (in seconds) before this command “times out”
  • subsystem – the subsystem that the command requires @see IsTimedOut()
assertUnlocked(message: str) → bool

If changes are locked, then this will generate a CommandIllegalUse error.

Parameters:message – The message to report on error (it is appended by a default message)
Returns:True if assert passed, false if assert failed.
cancel() → None

This will cancel the current command.

This will cancel the current command eventually. It can be called multiple times. And it can be called when the command is not running. If the command is running though, then the command will be marked as canceled and eventually removed.

A command can not be canceled if it is a part of a command group, you must cancel the command group instead.

clearRequirements() → None

Clears list of subsystem requirements.

This is only used by ConditionalCommand so cancelling the chosen command works properly in CommandGroup.

doesRequire(subsystem: frc::Subsystem) → bool

Checks if the command requires the given Subsystem.

Parameters:system – the system
Returns:whether or not the subsystem is required (false if given nullptr)
end() → None

Called when the command ended peacefully.

This is where you may want to wrap up loose ends, like shutting off a motor that was being used in the command.

execute() → None

The execute method is called repeatedly until this Command either finishes or is canceled.

getGroup() → frc::CommandGroup

Returns the CommandGroup that this command is a part of.

Will return null if this Command is not in a group.

Returns:The CommandGroup that this command is a part of (or null if not in group)
getID() → int

Get the ID (sequence number) for this command.

The ID is a unique sequence number that is incremented for each command.

Returns:The ID of this command
getName() → str

Gets the name of this Command.

Returns:Name
getRequirements() → wpi::SmallPtrSetImpl<frc::Subsystem*>

Returns the requirements (as an std::set of Subsystem pointers) of this command.

Returns:The requirements (as an std::set of Subsystem pointers) of this command
getSubsystem() → str

Gets the subsystem name of this Command.

Returns:Subsystem name
initSendable(builder: wpilib._wpilib.SendableBuilder) → None
initialize() → None

The initialize method is called the first time this Command is run after being started.

interrupted() → None

Called when the command ends because somebody called Cancel() or another command shared the same requirements as this one, and booted it out.

This is where you may want to wrap up loose ends, like shutting off a motor that was being used in the command.

Generally, it is useful to simply call the End() method within this method, as done here.

isCanceled() → bool

Returns whether or not this has been canceled.

Returns:whether or not this has been canceled
isCompleted() → bool

Returns whether or not the command has completed running.

Returns:whether or not the command has completed running.
isFinished() → bool

Returns whether this command is finished.

If it is, then the command will be removed and End() will be called.

It may be useful for a team to reference the IsTimedOut() method for time-sensitive commands.

Returning false will result in the command never ending automatically. It may still be cancelled manually or interrupted by another command. Returning true will result in the command executing once and finishing immediately. We recommend using InstantCommand for this.

Returns:Whether this command is finished. @see IsTimedOut()
isInitialized() → bool

Returns whether or not the command has been initialized.

Returns:whether or not the command has been initialized.
isInterruptible() → bool

Returns whether or not this command can be interrupted.

Returns:whether or not this command can be interrupted
isParented() → bool

Returns whether the command has a parent.

Parameters:True – if the command has a parent.
isRunning() → bool

Returns whether or not the command is running.

This may return true even if the command has just been canceled, as it may not have yet called Interrupted().

Returns:whether or not the command is running
isTimedOut() → bool

Returns whether or not the TimeSinceInitialized() method returns a number which is greater than or equal to the timeout for the command.

If there is no timeout, this will always return false.

Returns:whether the time has expired
requires(s: frc::Subsystem) → None

This method specifies that the given Subsystem is used by this command.

This method is crucial to the functioning of the Command System in general.

Note that the recommended way to call this method is in the constructor.

Parameters:subsystem – The Subsystem required @see Subsystem
run() → bool

The run method is used internally to actually run the commands.

Returns:Whether or not the command should stay within the Scheduler.
setInterruptible(interruptible: bool) → None

Sets whether or not this command can be interrupted.

Parameters:interruptible – whether or not this command can be interrupted
setName(name: str) → None

Sets the name of this Command.

Parameters:name – name
setParent(parent: frc::CommandGroup) → None

Sets the parent of this command. No actual change is made to the group.

Parameters:parent – the parent
setRunWhenDisabled(run: bool) → None

Sets whether or not this Command should run when the robot is disabled.

By default a command will not run when the robot is disabled, and will in fact be canceled.

Parameters:run – Whether this command should run when the robot is disabled.
setSubsystem(subsystem: str) → None

Sets the subsystem name of this Command.

Parameters:subsystem – subsystem name
setTimeout(timeout: float) → None

Sets the timeout of this command.

Parameters:timeout – the timeout (in seconds) @see IsTimedOut()
start() → None

Starts up the command. Gets the command ready to start.

Note that the command will eventually start, however it will not necessarily do so immediately, and may in fact be canceled before initialize is even called.

timeSinceInitialized() → float

Returns the time since this command was initialized (in seconds).

This function will work even if there is no specified timeout.

Returns:the time since this command was initialized (in seconds).
willRunWhenDisabled() → bool

Returns whether or not this Command will run when the robot is disabled, or if it will cancel itself.

Returns:Whether this Command will run when the robot is disabled, or if it will cancel itself.