命令模式

意图：将一个请求封装成一个对象，从而使您可以用不同的请求对客户进行参数化。
主要解决：在软件系统中，行为请求者与行为实现者通常是一种紧耦合的关系，但某些场合，比如需要对行为进行记录、撤销或重做、事务等处理时，这种无法抵御变化的紧耦合的设计就不太合适。

代码:

#include <iostream>
#include <list>
using namespace std;

// 厨师
class Cook
{
public:
    void cookChicken()
    {
        cout << "cook chicken" << endl;
    }

    void cookBeef()
    {
        cout << "cook beaf" << endl;
    }
};

class Command
{
public:
    virtual ~Command() {}
    Command(Cook *c) :_cook(c) {}
public:
    virtual void executeCmd() = 0;
protected:
    Cook *_cook;
};


class CookChicken : public Command
{
public:
    CookChicken(Cook *c) :Command(c){}

public:
    virtual void executeCmd()
    {
        _cook->cookChicken();
    }
};

class CookBeef : public Command
{
public:
    CookBeef(Cook *c) :Command(c){}

public:
    virtual void executeCmd()
    {
        _cook->cookBeef();
    }
};

class Waiter
{
public:
    Waiter()
    {
        _commandList.clear();
    }

    ~Waiter()
    {
        _commandList.clear();
    }

    void addOrder(Command *c)
    {
        cout << "增加订单" << endl;
        _commandList.push_back(c);
    }

    void notify()
    {
        for (auto it = _commandList.begin(); it != _commandList.end(); ++it)
        {
            (*it)->executeCmd();
        }
        _commandList.clear();
    }

private:
    list<Command *> _commandList;
};

void test()
{
    Cook *cook = new Cook();    // 厨师
    Waiter *waiter = new Waiter();  // 服务员
    Command *cmd1 = new CookChicken(cook);
    Command *cmd2 = new CookBeef(cook);
    waiter->addOrder(cmd1);
    waiter->addOrder(cmd2);

    waiter->notify(); // 发送通知

    delete cook;
    delete waiter;
    delete cmd1;
    delete cmd2;
}

int main()
{
    test();
    cin.get();
    return 0;
}

效果: