A state machine representing a complete action to be performed by the robot. More...

#include <frc2/command/Command.h>

Inheritance diagram for frc2::Command:

Public Types
enum class	InterruptionBehavior { kCancelSelf , kCancelIncoming }
	An enum describing the command's behavior when another command with a shared requirement is scheduled. More...

Public Member Functions
	~Command () override

	Command (const Command &)=default

Command &	operator= (const Command &rhs)

	Command (Command &&)=default

Command &	operator= (Command &&)=default

virtual void	Initialize ()
	The initial subroutine of a command.

virtual void	Execute ()
	The main body of a command.

virtual void	End (bool interrupted)
	The action to take when the command ends.

virtual bool	IsFinished ()
	Whether the command has finished.

virtual wpi::SmallSet< Subsystem *, 4 >	GetRequirements () const
	Specifies the set of subsystems used by this command.

void	AddRequirements (Requirements requirements)
	Adds the specified Subsystem requirements to the command.

void	AddRequirements (wpi::SmallSet< Subsystem *, 4 > requirements)
	Adds the specified Subsystem requirements to the command.

void	AddRequirements (Subsystem *requirement)
	Adds the specified Subsystem requirement to the command.

std::string	GetName () const
	Gets the name of this Command.

void	SetName (std::string_view name)
	Sets the name of this Command.

std::string	GetSubsystem () const
	Gets the subsystem name of this Command.

void	SetSubsystem (std::string_view subsystem)
	Sets the subsystem name of this Command.

CommandPtr	WithTimeout (units::second_t duration) &&
	Decorates this command with a timeout.

CommandPtr	Until (std::function< bool()> condition) &&
	Decorates this command with an interrupt condition.

CommandPtr	OnlyWhile (std::function< bool()> condition) &&
	Decorates this command with a run condition.

CommandPtr	BeforeStarting (std::function< void()> toRun, Requirements requirements={}) &&
	Decorates this command with a runnable to run before this command starts.

CommandPtr	BeforeStarting (CommandPtr &&before) &&
	Decorates this command with another command to run before this command starts.

CommandPtr	AndThen (std::function< void()> toRun, Requirements requirements={}) &&
	Decorates this command with a runnable to run after the command finishes.

CommandPtr	AndThen (CommandPtr &&next) &&
	Decorates this command with a set of commands to run after it in sequence.

CommandPtr	Repeatedly () &&
	Decorates this command to run repeatedly, restarting it when it ends, until this command is interrupted.

CommandPtr	AsProxy () &&
	Decorates this command to run "by proxy" by wrapping it in a ProxyCommand.

CommandPtr	Unless (std::function< bool()> condition) &&
	Decorates this command to only run if this condition is not met.

CommandPtr	OnlyIf (std::function< bool()> condition) &&
	Decorates this command to only run if this condition is met.

CommandPtr	WithDeadline (CommandPtr &&deadline) &&
	Creates a new command that runs this command and the deadline in parallel, finishing (and interrupting this command) when the deadline finishes.

CommandPtr	DeadlineFor (CommandPtr &&parallel) &&
	Decorates this command with a set of commands to run parallel to it, ending when the calling command ends and interrupting all the others.

CommandPtr	AlongWith (CommandPtr &&parallel) &&
	Decorates this command with a set of commands to run parallel to it, ending when the last command ends.

CommandPtr	RaceWith (CommandPtr &&parallel) &&
	Decorates this command with a set of commands to run parallel to it, ending when the first command ends.

CommandPtr	IgnoringDisable (bool doesRunWhenDisabled) &&
	Decorates this command to run or stop when disabled.

CommandPtr	WithInterruptBehavior (Command::InterruptionBehavior interruptBehavior) &&
	Decorates this command to have a different interrupt behavior.

CommandPtr	FinallyDo (std::function< void(bool)> end) &&
	Decorates this command with a lambda to call on interrupt or end, following the command's inherent Command::End(bool) method.

CommandPtr	FinallyDo (std::function< void()> end) &&
	Decorates this command with a lambda to call on interrupt or end, following the command's inherent Command::End(bool) method.

CommandPtr	HandleInterrupt (std::function< void()> handler) &&
	Decorates this command with a lambda to call on interrupt, following the command's inherent Command::End(bool) method.

CommandPtr	WithName (std::string_view name) &&
	Decorates this Command with a name.

void	Schedule ()
	Schedules this command.

void	Cancel ()
	Cancels this command.

bool	IsScheduled () const
	Whether or not the command is currently scheduled.

bool	HasRequirement (Subsystem *requirement) const
	Whether the command requires a given subsystem.

bool	IsComposed () const
	Whether the command is currently grouped in a command group.

void	SetComposed (bool isComposed)
	Sets whether the command is currently composed in a command composition.

std::optional< std::string >	GetPreviousCompositionSite () const
	Get the stacktrace of where this command was composed, or an empty optional.

virtual bool	RunsWhenDisabled () const
	Whether the given command should run when the robot is disabled.

virtual InterruptionBehavior	GetInterruptionBehavior () const
	How the command behaves when another command with a shared requirement is scheduled.

virtual CommandPtr	ToPtr () &&=0
	Transfers ownership of this command to a unique pointer.

void	InitSendable (wpi::SendableBuilder &builder) override
	Initializes this Sendable object.

Public Member Functions inherited from wpi::Sendable
virtual constexpr	~Sendable ()=default

Public Member Functions inherited from wpi::SendableHelper< Command >
constexpr	SendableHelper (const SendableHelper &rhs)=default

constexpr	SendableHelper (SendableHelper &&rhs)

constexpr SendableHelper &	operator= (const SendableHelper &rhs)=default

constexpr SendableHelper &	operator= (SendableHelper &&rhs)

Protected Member Functions
	Command ()

Protected Member Functions inherited from wpi::SendableHelper< Command >
constexpr	SendableHelper ()=default

constexpr	~SendableHelper ()

Friends
class	CommandPtr

Detailed Description

A state machine representing a complete action to be performed by the robot.

Commands are run by the CommandScheduler, and can be composed into CommandGroups to allow users to build complicated multi-step actions without the need to roll the state machine logic themselves.

Commands are run synchronously from the main robot loop; no multithreading is used, unless specified explicitly from the command implementation.

Note: ALWAYS create a subclass by extending CommandHelper<Base, Subclass>, or decorators will not function!

This class is provided by the NewCommands VendorDep

See also: CommandScheduler; CommandHelper

Member Enumeration Documentation

◆ InterruptionBehavior

enum class frc2::Command::InterruptionBehavior

strong

An enum describing the command's behavior when another command with a shared requirement is scheduled.

Enumerator

kCancelSelf

This command ends, End(true) is called, and the incoming command is scheduled normally.

This is the default behavior.

kCancelIncoming

This command continues, and the incoming command is not scheduled.

Constructor & Destructor Documentation

◆ ~Command()

frc2::Command::~Command ( )

override

◆ Command() [1/3]

frc2::Command::Command ( const Command & )

default

◆ Command() [2/3]

frc2::Command::Command ( Command && )

default

◆ Command() [3/3]

frc2::Command::Command ( )

protected

Member Function Documentation

◆ AddRequirements() [1/3]

void frc2::Command::AddRequirements ( Requirements requirements )

Adds the specified Subsystem requirements to the command.

The scheduler will prevent two commands that require the same subsystem from being scheduled simultaneously.

Note that the scheduler determines the requirements of a command when it is scheduled, so this method should normally be called from the command's constructor.

While this overload can be used with AddRequirements({&subsystem1, &subsystem2}), AddRequirements({&subsystem}) selects the AddRequirements(Subsystem*) overload, which will function identically but may cause warnings about redundant braces.

Parameters

requirements the Subsystem requirements to add, which can be implicitly constructed from an initializer list or a span

◆ AddRequirements() [2/3]

void frc2::Command::AddRequirements ( Subsystem * requirement )

Adds the specified Subsystem requirement to the command.

The scheduler will prevent two commands that require the same subsystem from being scheduled simultaneously.

Note that the scheduler determines the requirements of a command when it is scheduled, so this method should normally be called from the command's constructor.

Parameters

requirement the Subsystem requirement to add

◆ AddRequirements() [3/3]

void frc2::Command::AddRequirements ( wpi::SmallSet< Subsystem *, 4 > requirements )

Adds the specified Subsystem requirements to the command.

The scheduler will prevent two commands that require the same subsystem from being scheduled simultaneously.

Note that the scheduler determines the requirements of a command when it is scheduled, so this method should normally be called from the command's constructor.

Parameters

requirements the Subsystem requirements to add

◆ AlongWith()

CommandPtr frc2::Command::AlongWith ( CommandPtr && parallel ) &&

nodiscard

Decorates this command with a set of commands to run parallel to it, ending when the last command ends.

Often more convenient/less-verbose than constructing a new ParallelCommandGroup explicitly.

Parameters

parallel the commands to run in parallel

Returns: the decorated command

◆ AndThen() [1/2]

CommandPtr frc2::Command::AndThen ( CommandPtr && next ) &&

nodiscard

Decorates this command with a set of commands to run after it in sequence.

Often more convenient/less-verbose than constructing a SequentialCommandGroup explicitly.

Parameters

next	the commands to run next

Returns: the decorated command

◆ AndThen() [2/2]

CommandPtr frc2::Command::AndThen	(	std::function< void()>	toRun,
		Requirements	requirements = {} ) &&

nodiscard

Decorates this command with a runnable to run after the command finishes.

Parameters

toRun	the Runnable to run
requirements	the required subsystems

Returns: the decorated command

◆ AsProxy()

CommandPtr frc2::Command::AsProxy ( ) &&

nodiscard

Decorates this command to run "by proxy" by wrapping it in a ProxyCommand.

Use this for "forking off" from command compositions when the user does not wish to extend the command's requirements to the entire command composition. ProxyCommand has unique implications and semantics, see the WPILib docs for a full explanation.

This overload transfers command ownership to the returned CommandPtr.

Returns: the decorated command

See also: ProxyCommand

◆ BeforeStarting() [1/2]

CommandPtr frc2::Command::BeforeStarting ( CommandPtr && before ) &&

nodiscard

Decorates this command with another command to run before this command starts.

Parameters

before the command to run before this one

Returns: the decorated command

◆ BeforeStarting() [2/2]

CommandPtr frc2::Command::BeforeStarting	(	std::function< void()>	toRun,
		Requirements	requirements = {} ) &&

nodiscard

Decorates this command with a runnable to run before this command starts.

Parameters

toRun	the Runnable to run
requirements	the required subsystems

Returns: the decorated command

◆ Cancel()

void frc2::Command::Cancel ( )

Cancels this command.

Will call End(true). Commands will be canceled regardless of interruption behavior.

◆ DeadlineFor()

CommandPtr frc2::Command::DeadlineFor ( CommandPtr && parallel ) &&

nodiscard

Decorates this command with a set of commands to run parallel to it, ending when the calling command ends and interrupting all the others.

Often more convenient/less-verbose than constructing a new ParallelDeadlineGroup explicitly.

Parameters

parallel the commands to run in parallel. Note the parallel commands will be interupted when the deadline command ends

Returns: the decorated command

See also: WithDeadline

◆ End()

virtual void frc2::Command::End ( bool interrupted )

virtual

The action to take when the command ends.

Called when either the command finishes normally, or when it interrupted/canceled.

Parameters

interrupted whether the command was interrupted/canceled

◆ Execute()

virtual void frc2::Command::Execute ( )

virtual

The main body of a command.

Called repeatedly while the command is scheduled.

◆ FinallyDo() [1/2]

CommandPtr frc2::Command::FinallyDo ( std::function< void()> end ) &&

nodiscard

Decorates this command with a lambda to call on interrupt or end, following the command's inherent Command::End(bool) method.

The provided lambda will run identically in both interrupt and end cases.

Parameters

end	a lambda to run when the command ends, whether or not it was interrupted.

Returns: the decorated command

◆ FinallyDo() [2/2]

CommandPtr frc2::Command::FinallyDo ( std::function< void(bool)> end ) &&

nodiscard

Decorates this command with a lambda to call on interrupt or end, following the command's inherent Command::End(bool) method.

Parameters

end	a lambda accepting a boolean parameter specifying whether the command was interrupted.

Returns: the decorated command

◆ GetInterruptionBehavior()

virtual InterruptionBehavior frc2::Command::GetInterruptionBehavior ( ) const

inlinevirtual

How the command behaves when another command with a shared requirement is scheduled.

Returns: a variant of InterruptionBehavior, defaulting to kCancelSelf.

◆ GetName()

std::string frc2::Command::GetName ( ) const

Gets the name of this Command.

Returns: Name

◆ GetPreviousCompositionSite()

std::optional< std::string > frc2::Command::GetPreviousCompositionSite ( ) const

Get the stacktrace of where this command was composed, or an empty optional.

Intended for internal use.

Returns: optional string representation of the composition site stack trace.

◆ GetRequirements()

virtual wpi::SmallSet< Subsystem *, 4 > frc2::Command::GetRequirements ( ) const

virtual

Specifies the set of subsystems used by this command.

Two commands cannot use the same subsystem at the same time. If another command is scheduled that shares a requirement, GetInterruptionBehavior() will be checked and followed. If no subsystems are required, return an empty set.

Note: it is recommended that user implementations contain the requirements as a field, and return that field here, rather than allocating a new set every time this is called.

Returns: the set of subsystems that are required

See also: InterruptionBehavior

◆ GetSubsystem()

std::string frc2::Command::GetSubsystem ( ) const

Gets the subsystem name of this Command.

Returns: Subsystem name

◆ HandleInterrupt()

CommandPtr frc2::Command::HandleInterrupt ( std::function< void()> handler ) &&

nodiscard

Decorates this command with a lambda to call on interrupt, following the command's inherent Command::End(bool) method.

Parameters

handler a lambda to run when the command is interrupted

Returns: the decorated command

◆ HasRequirement()

bool frc2::Command::HasRequirement ( Subsystem * requirement ) const

Whether the command requires a given subsystem.

Named "HasRequirement" rather than "requires" to avoid confusion with Command::Requires(Subsystem) – this may be able to be changed in a few years.

Parameters

requirement the subsystem to inquire about

Returns: whether the subsystem is required

◆ IgnoringDisable()

CommandPtr frc2::Command::IgnoringDisable ( bool doesRunWhenDisabled ) &&

nodiscard

Decorates this command to run or stop when disabled.

Parameters

doesRunWhenDisabled true to run when disabled.

Returns: the decorated command

◆ Initialize()

virtual void frc2::Command::Initialize ( )

virtual

The initial subroutine of a command.

Called once when the command is initially scheduled.

◆ InitSendable()

void frc2::Command::InitSendable ( wpi::SendableBuilder & builder )

overridevirtual

Initializes this Sendable object.

Parameters

builder sendable builder

Implements wpi::Sendable.

◆ IsComposed()

bool frc2::Command::IsComposed ( ) const

Whether the command is currently grouped in a command group.

Used as extra insurance to prevent accidental independent use of grouped commands.

◆ IsFinished()

virtual bool frc2::Command::IsFinished ( )

inlinevirtual

Whether the command has finished.

Once a command finishes, the scheduler will call its end() method and un-schedule it.

Returns: whether the command has finished.

◆ IsScheduled()

bool frc2::Command::IsScheduled ( ) const

Whether or not the command is currently scheduled.

Note that this does not detect whether the command is in a composition, only whether it is directly being run by the scheduler.

Returns: Whether the command is scheduled.

◆ OnlyIf()

CommandPtr frc2::Command::OnlyIf ( std::function< bool()> condition ) &&

nodiscard

Decorates this command to only run if this condition is met.

If the command is already running and the condition changes to false, the command will not stop running. The requirements of this command will be kept for the new conditional command.

Parameters

condition the condition that will allow the command to run

Returns: the decorated command

◆ OnlyWhile()

CommandPtr frc2::Command::OnlyWhile ( std::function< bool()> condition ) &&

nodiscard

Decorates this command with a run condition.

If the specified condition becomes false before the command finishes normally, the command will be interrupted and un-scheduled.

Parameters

condition the run condition

Returns: the command with the run condition added

◆ operator=() [1/2]

Command & frc2::Command::operator= ( Command && )

default

◆ operator=() [2/2]

Command & frc2::Command::operator= ( const Command & rhs )

◆ RaceWith()

CommandPtr frc2::Command::RaceWith ( CommandPtr && parallel ) &&

nodiscard

Decorates this command with a set of commands to run parallel to it, ending when the first command ends.

Often more convenient/less-verbose than constructing a new ParallelRaceGroup explicitly.

Parameters

parallel the commands to run in parallel

Returns: the decorated command

◆ Repeatedly()

CommandPtr frc2::Command::Repeatedly ( ) &&

nodiscard

Decorates this command to run repeatedly, restarting it when it ends, until this command is interrupted.

The decorated command can still be canceled.

Returns: the decorated command

◆ RunsWhenDisabled()

virtual bool frc2::Command::RunsWhenDisabled ( ) const

inlinevirtual

Whether the given command should run when the robot is disabled.

Override to return true if the command should run when disabled.

Returns: whether the command should run when the robot is disabled

◆ Schedule()

void frc2::Command::Schedule ( )

Schedules this command.

◆ SetComposed()

void frc2::Command::SetComposed ( bool isComposed )

Sets whether the command is currently composed in a command composition.

Can be used to "reclaim" a command if a composition is no longer going to use it. NOT ADVISED!

◆ SetName()

void frc2::Command::SetName ( std::string_view name )

Sets the name of this Command.

Parameters

name name

◆ SetSubsystem()

void frc2::Command::SetSubsystem ( std::string_view subsystem )

Sets the subsystem name of this Command.

Parameters

subsystem subsystem name

◆ ToPtr()

virtual CommandPtr frc2::Command::ToPtr ( ) &&

pure virtual

Transfers ownership of this command to a unique pointer.

Used for decorator methods.

◆ Unless()

CommandPtr frc2::Command::Unless ( std::function< bool()> condition ) &&

nodiscard

Decorates this command to only run if this condition is not met.

If the command is already running and the condition changes to true, the command will not stop running. The requirements of this command will be kept for the new conditional command.

Parameters

condition the condition that will prevent the command from running

Returns: the decorated command

◆ Until()

CommandPtr frc2::Command::Until ( std::function< bool()> condition ) &&

nodiscard

Decorates this command with an interrupt condition.

If the specified condition becomes true before the command finishes normally, the command will be interrupted and un-scheduled.

Parameters

condition the interrupt condition

Returns: the command with the interrupt condition added

◆ WithDeadline()

CommandPtr frc2::Command::WithDeadline ( CommandPtr && deadline ) &&

Creates a new command that runs this command and the deadline in parallel, finishing (and interrupting this command) when the deadline finishes.

Parameters

deadline the deadline of the command group

Returns: the decorated command

See also: DeadlineFor

◆ WithInterruptBehavior()

CommandPtr frc2::Command::WithInterruptBehavior ( Command::InterruptionBehavior interruptBehavior ) &&

nodiscard

Decorates this command to have a different interrupt behavior.

Parameters

interruptBehavior the desired interrupt behavior

Returns: the decorated command

◆ WithName()

CommandPtr frc2::Command::WithName ( std::string_view name ) &&

nodiscard

Decorates this Command with a name.

Parameters

name name

Returns: the decorated Command

◆ WithTimeout()

CommandPtr frc2::Command::WithTimeout ( units::second_t duration ) &&

nodiscard

Decorates this command with a timeout.

If the specified timeout is exceeded before the command finishes normally, the command will be interrupted and un-scheduled.

Parameters

duration the timeout duration

Returns: the command with the timeout added

Friends And Related Symbol Documentation

◆ CommandPtr

friend class CommandPtr

friend

The documentation for this class was generated from the following file:

frc2/command/Command.h

Public Types

Public Member Functions

Protected Member Functions

Friends

Detailed Description

Member Enumeration Documentation

◆ InterruptionBehavior

Constructor & Destructor Documentation

◆ ~Command()

◆ Command() [1/3]

◆ Command() [2/3]

◆ Command() [3/3]

Member Function Documentation

◆ AddRequirements() [1/3]

◆ AddRequirements() [2/3]

◆ AddRequirements() [3/3]

◆ AlongWith()

◆ AndThen() [1/2]

◆ AndThen() [2/2]

◆ AsProxy()

◆ BeforeStarting() [1/2]

◆ BeforeStarting() [2/2]

◆ Cancel()

◆ DeadlineFor()

◆ End()

◆ Execute()

◆ FinallyDo() [1/2]

◆ FinallyDo() [2/2]

◆ GetInterruptionBehavior()

◆ GetName()

◆ GetPreviousCompositionSite()

◆ GetRequirements()

◆ GetSubsystem()

◆ HandleInterrupt()

◆ HasRequirement()

◆ IgnoringDisable()

◆ Initialize()

◆ InitSendable()

◆ IsComposed()

◆ IsFinished()

◆ IsScheduled()

◆ OnlyIf()

◆ OnlyWhile()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ RaceWith()

◆ Repeatedly()

◆ RunsWhenDisabled()

◆ Schedule()

◆ SetComposed()

◆ SetName()

◆ SetSubsystem()

◆ ToPtr()

◆ Unless()

◆ Until()

◆ WithDeadline()

◆ WithInterruptBehavior()

◆ WithName()

◆ WithTimeout()

Friends And Related Symbol Documentation

◆ CommandPtr