为指令写代码。

子系统类让机器人的机械装置移动，但为了让它在正确的时间停止并通过更复杂的操作顺序，你编写命令。之前在:doc:编写子系统代码时，我们为机器人上的`Claw 子系统开发了代码，用于启动爪子张开、闭合或停止移动。现在我们将为一个命令编写代码，该指令将在正确的时间实际运行爪形电机，以使爪形打开和关闭。我们的爪形示例是一个非常简单的机制，我们运行电机 1 秒钟以将其打开或直到限位开关跳闸将其关闭。

在 RobotBuilder 中关闭 Claw 指令

这是 RobotBuilder 中 CloseClaw 指令的定义。请注意，它需要 Claw 子系统。这将在下一步中解释。

生成的 CloseClaw 类

JAVA

// ROBOTBUILDER TYPE: Command.

package frc.robot.commands;
import edu.wpi.first.wpilibj2.command.CommandBase;

// BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=IMPORTS
import frc.robot.subsystems.Claw;

    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=IMPORTS

/**
*
*/
public class CloseClaw extends CommandBase {

    // BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=VARIABLE_DECLARATIONS
        private final Claw m_claw;

    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=VARIABLE_DECLARATIONS

    // BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=CONSTRUCTORS


    public CloseClaw(Claw subsystem) {


    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=CONSTRUCTORS
        // BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=VARIABLE_SETTING

    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=VARIABLE_SETTING
        // BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=REQUIRES

        m_claw = subsystem;
        addRequirements(m_claw);

    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=REQUIRES
    }

    // Called when the command is initially scheduled.
    @Override
    public void initialize() {
        m_claw.close(); // (1)
    }

    // Called every time the scheduler runs while the command is scheduled.
    @Override
    public void execute() {
    }

    // Called once the command ends or is interrupted.
    @Override
    public void end(boolean interrupted) {
        m_claw.stop(); // (3)
    }

    // Returns true when the command should end.
    @Override
    public boolean isFinished() {
        return m_claw.isGripping(); // (2)
    }

    @Override
    public boolean runsWhenDisabled() {
        // BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=DISABLED
        return false;

    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=DISABLED
    }
}

C++

// ROBOTBUILDER TYPE: Command.

// BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=CONSTRUCTOR

#include "commands/CloseClaw.h"

CloseClaw::CloseClaw(Claw* m_claw)
:m_claw(m_claw){

    // Use AddRequirements() here to declare subsystem dependencies
    // eg. AddRequirements(m_Subsystem);
    SetName("CloseClaw");
    AddRequirements({m_claw});

// END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=CONSTRUCTOR

}

// Called just before this Command runs the first time
void CloseClaw::Initialize() {
    m_claw->Close(); // (1)
}

// Called repeatedly when this Command is scheduled to run
void CloseClaw::Execute() {

}

// Make this return true when this Command no longer needs to run execute()
bool CloseClaw::IsFinished() {
    return m_claw->IsGripping(); // (2)
}

// Called once after isFinished returns true
void CloseClaw::End(bool interrupted) {
    m_claw->Stop(); // (3)
}

bool CloseClaw::RunsWhenDisabled() const {
    // BEGIN AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=DISABLED
    return false;

    // END AUTOGENERATED CODE, SOURCE=ROBOTBUILDER ID=DISABLED
}

RobotBuilder 将为`CloseClaw` 指令生成类文件。指令代表了爪子的行为，即随着时间的推移进行的操作。要操作这个非常简单的爪形机构，电机需要在关闭方向上运行。 Claw 子系统具有启动和停止电机向正确方向运行的方法。命令的职责是在正确的时间运行电机。添加框中显示的代码行以添加此行为。

1. 通过调用在 CloseClaw Initialize 方法中添加到 Claw 子系统的 Close() 方法，启动爪形电机朝关闭方向移动。

2. This command is finished when the limit switch in the Claw subsystem is tripped.

3. End() 方法在命令完成时被调用，它是一个清理的地方。在这种情况下，电机停止，因为时间已用完。