unloadcommand.java

本书透彻讲解了经典的《设计模式：可复用面向对象软件的基础》一书涵盖的23种基本设计模式。本书将这些设计模式分成五类：接口型模式、责任型模式、构造型模式、操作型模式

package com.oozinoz.robot.interpreter;

import com.oozinoz.machine.*;

/*
 * Copyright (c) 2001 Steven J. Metsker.
 * 
 * Steve Metsker makes no representations or warranties about
 * the fitness of this software for any particular purpose, 
 * including the implied warranty of merchantability.
 *
 * Please use this software as you wish with the sole
 * restriction that you may not claim that you wrote it.
 */
/**
 * This class represents a command to unload a machine
 * indicated by a provided term.
 * 
 * @author Steven J. Metsker
 */
public class UnloadCommand extends Command 
{
	protected Term term;
/**
 * Construct a command to unload a machine indicated by 
 * the provided term.
 *
 * @param Term a term to evaulate when this command executes;
 *             the machine it evaulates to will be unloaded
 */
public UnloadCommand(Term term)
{
	this.term = term;
}
/**
 * Return true if the provided object equals this one.
 *
 * @return true if the provided object equals this one
 */
public boolean equals(Object o)
{
	if (o == this)
		return true;
	if (!(o instanceof UnloadCommand))
		return false;
	UnloadCommand uc = (UnloadCommand) o;
	return term.equals(uc.term);
}
/**
 * Evaluate this object's term to a machine and unload
 * that machine.
 */
public void execute(Context c)
{
	Machine m = term.eval(c);
	m.unload();
}
}