设计模式十五（命令模式，python语言实现）

基本原理请参考相应书籍，这里直接给实例

被控对象是机器人Robot，人（Client），通过控制器（controller）编程，给机器人发送指令。

Comand是指令的父类，具体指令有GoAhead（前进），GoBack（后退），GoLeft（向左），GoRight（向右）

# -*- coding: utf-8 -*-######################################################## # command.py# Python implementation of the Class Client# Generated by Enterprise Architect# Created on:      12-十二?012 16:06:11# #######################################################from __future__ import divisionfrom __future__ import print_functionfrom __future__ import unicode_literalsfrom future_builtins import *class Robot:    """This class knows how to perform the operations associated with carrying out a    request.    """    def Move(self, direction,step):        print("I am robot,now "+direction+" by:%d step"%step )        pass    class Command(object):    """This class declares an interface for executing an operation.    """    m_Robot= Robot()    def __init__(self, direction="None", step="None"):        self.direction=direction        self.step=step        pass    def Execute():                passclass GoAhead(Command):    """This class (a) defines a binding between a Receiver object and an action, and    (b) implements Execute by invoking the corresponding operation(s) on Receiver.    """    def __init__(self, direction='GoAhead', step=1):        super(GoAhead,self).__init__(direction,step)        pass    def Execute(self):        # receiver->Action();        Command.m_Robot.Move(self.direction,self.step)        passclass GoBack(Command):    """This class (a) defines a binding between a Receiver object and an action, and    (b) implements Execute by invoking the corresponding operation(s) on Receiver.    """    def __init__(self, direction='GoBack', step=1):        super(GoBack,self).__init__(direction,step)        pass    def Execute(self):        # receiver->Action();        Command.m_Robot.Move(self.direction,self.step)        passclass GoLeft(Command):    """This class (a) defines a binding between a Receiver object and an action, and    (b) implements Execute by invoking the corresponding operation(s) on Receiver.    """    def __init__(self, direction='GoLeft', step=1):        super(GoLeft,self).__init__(direction,step)        pass    def Execute(self):        # receiver->Action();        Command.m_Robot.Move(self.direction,self.step)        passclass GoRight(Command):    """This class (a) defines a binding between a Receiver object and an action, and    (b) implements Execute by invoking the corresponding operation(s) on Receiver.    """    def __init__(self, direction='GoRight', step=1):        super(GoRight,self).__init__(direction,step)        pass    def Execute(self):        # receiver->Action();        Command.m_Robot.Move(self.direction,self.step)        pass    class Controller(object):    """This class asks the command to carry out the request.    """    m_Command= Command()    def __init__(self):        self.ls=list()        pass    def AddOperation(self, command):        self.ls.append(command)        pass    def Execute(self):        for i in xrange(len(self.ls)):            item=self.ls.pop(0)            item.Execute()                                pass#客户端class Client:    """This class creates a ConcreteCommand object and sets its receiver.    """    m_Controller= Controller()    m_Controller.AddOperation(GoAhead(step=12))    m_Controller.AddOperation(GoBack(step=4))        m_Controller.AddOperation(GoLeft(step=3))    m_Controller.AddOperation(GoRight(step=5))           m_Controller.Execute()        print("\n")    m_Controller.AddOperation(GoAhead(step=20))    m_Controller.AddOperation(GoBack(step=44))        m_Controller.AddOperation(GoLeft(step=34))    m_Controller.AddOperation(GoRight(step=50))           m_Controller.Execute()    

运行结果：