备忘录模式的简单实现

#include <time.h>
#include <stdlib.h>

//类的声明（只要在CGameRole中没有使用具体的对象就没有关系）
//如果在CGameRole中使用了具体的该声明的类的对象，那么这样声明也是没有用的

class CMemento;		
class CGameRole
{
public:
	void Init()
	{
		m_hp = 100;
		m_def = 100;
		m_attck = 100;
	}

	void ShowState()
	{
		printf("血量：%d\n",m_hp);
		printf("防御值：%d\n", m_def);
		printf("攻击值：%d\n\n", m_attck);
	}
	//战斗
	void Fight()
	{
		srand((unsigned)time(nullptr));
		m_hp -= rand() % 100;
		m_def -= rand() % 100;
		m_attck -= rand() % 100;
	}
private:
	int m_hp;
	int m_def;
	int m_attck;
	friend CMemento;		//直接使用备忘录类作为该游戏对象的友元类，感觉更方便呀，也不会破坏CGameRole的封装性
};

//备忘录
class CMemento
{
public:
	CMemento()
	{
		m_pGameRole = nullptr;
	}
	void  SaveState(CGameRole* pMemento)
	{
		m_pGameRole = new CGameRole;
		m_pGameRole->m_attck = pMemento->m_attck;
		m_pGameRole->m_def = pMemento->m_def;
		m_pGameRole->m_hp = pMemento->m_hp;
	}
	void RecoverState(CGameRole* pMenento)
	{
		pMenento->m_attck = m_pGameRole->m_attck;
		pMenento->m_def = m_pGameRole->m_def;
		pMenento->m_hp = m_pGameRole->m_hp;
		delete m_pGameRole;
		m_pGameRole = nullptr;
	}
private:
	CGameRole* m_pGameRole;
};
int main()
{
	//初始化角色
	CGameRole* lixiaoyao = new CGameRole;
	lixiaoyao->Init();
	printf("战斗前：\n");
	lixiaoyao->ShowState();
	//使用备忘录对象来保存战斗之前的状态值
	CMemento* pMemento = new CMemento;
	pMemento->SaveState(lixiaoyao);		
	//角色战斗后
	lixiaoyao->Fight();
	printf("战斗后：\n");
	lixiaoyao->ShowState();
	printf("游戏回退之后：\n");
	pMemento->RecoverState(lixiaoyao);
	lixiaoyao->ShowState();

	system("pause");
	return 0;
}