c++之命令模式

命令模式

定义：将一个请求封装为一个对象，从而可用不同的请求对客户进行参数化，对请求排队或者记录请求日志，以及支持可撤销的操作。

场景栗子：通信兵接收到司令官的命令，将这些命令发送给作战部队。

代码

#include<iostream>
#include <list>

using namespace std;
class Signalman;
class Action;

class Command
{
public:
	Command(Action *action)
	{
		m_action = action;
	}
	virtual void ExecuteOrder() = 0;//执行命令

protected:
	Action *m_action;
};

//行动
class Action
{
public:
	void attack(string name)
	{
		cout << "进攻高地" << name.c_str() << endl;
	}
	void retreat()
	{
		cout << "所有队伍撤退" << endl;
	}

private:
};

class AttackCommand :public Command
{
public:
	AttackCommand(Action *act,string name) :Command(act){
		m_name = name;
	}
	void ExecuteOrder(){
		m_action->attack(m_name);
	}
private:
	string m_name;
};

class RetreatCommand :public Command
{
public:
	RetreatCommand(Action *act) :Command(act){}
	void ExecuteOrder(){
		m_action->retreat();
	}
};

//通信兵
class Signalman
{
public:
	//通知军队
	void noticeArmy()
	{
		for (Command*c : m_commandList)
		{
			c->ExecuteOrder();
		}
	}
	//设置命令
	void setCommand(Command* command)
	{
		m_commandList.push_back(command);
	}
	//取消命令
	void cancelCommand(Command* command)
	{
		m_commandList.remove(command);
	}

private:
	list<Command*> m_commandList;
};

//客户端
int main()
{
	Action *act = new Action;
	Command *attack1 = new AttackCommand(act,"333");
	Command *attack2 = new AttackCommand(act, "298");
	Command *retreat = new RetreatCommand(act);

	Signalman *man = new Signalman;
	man->setCommand(attack1);
	man->setCommand(attack2);
	//下发进攻命令
	man->noticeArmy();

	cout << "----------久攻不下，损失惨重--------------" << endl;
	man->cancelCommand(attack1);
	man->cancelCommand(attack2);
	man->setCommand(retreat);
	//下发撤退命令
	man->noticeArmy();

	if (act){
		delete act;
		act = nullptr;
	}
	if (man){
		delete man;
		man = nullptr;
	}
	if (attack1){
		delete attack1;
		attack1 = nullptr;
	}
	if (attack2){
		delete attack2;
		attack2 = nullptr;
	}
	if (retreat){
		delete retreat;
		retreat = nullptr;
	}

	return 0;
}

效果：