設計模式——策略模式

Strategy.h

#pragma once
#include <iostream>
enum CashSuper_EM
{
	CASH_NORMAL = 0,
	CASH_REBATE = 1,
};
#define SAFE_DELETE(p) \
if(p)\
{\
		delete p; \
		p = nullptr;\
}\
// 收費系統，基類
class CashSuper
{
public:
		virtual double AcceptCash(double money) = 0;
};

// 正常收費
class CashNormal : public  CashSuper
{
public:
	double AcceptCash(double money)
	{
		return money;
	}
};

// 打折收費
class CashRebate : public CashSuper
{
public:
	CashRebate(double moneyRebate)
	{
		this->moneyRebate = moneyRebate;
	}

	double AcceptCash(double money)
	{
		return money* moneyRebate;
	}
private:
	double moneyRebate;	// 折扣
};

// 環境類CashContext
class CashContext
{
public:
	//1. 客戶端判斷哪個策略,然後傳遞CashSuper
	CashContext(CashSuper* cashSuper)
	{
		this->cs = cashSuper;
	}

	//2. 客戶端判斷轉移到CashContext
	CashContext(CashSuper_EM ce)
	{
		switch (ce)
		{
		case CASH_NORMAL:
			this->cs = new CashNormal();
			break;
		case CASH_REBATE:
			this->cs = new CashRebate(0.8);
			break;
		default:
			this->cs = new CashNormal();
			break;
		}
	}
	~CashContext()
	{
		std::cout << "SAFE_DELETE" << std::endl;
		SAFE_DELETE(this->cs);
	}
	double GetResult(double money)
	{
		if (cs != nullptr)
		{
			return cs->AcceptCash(money);
		}
		return money;
	}
private: 
	CashSuper* cs;// 改用智能指針
};

 main.cpp

#include "Strategy.h"
#include <iostream>
using namespace std;

int main()
{
	CashSuper_EM cashSuperStr[2] = { CASH_NORMAL,CASH_REBATE };
	double money[2] = { 100,100 };
	for (int i = 0; i < 2; ++i)
	{
		CashSuper * cashSuper = nullptr;
		CashContext* cashContext = nullptr;
		//1. 客戶端判斷哪個策略,然後傳遞CashSuper
		switch (cashSuperStr[i])
		{
		case CASH_NORMAL:
			cashSuper = new CashNormal();
			cashContext = new CashContext(cashSuper);
			break;
		case CASH_REBATE:
			cashSuper = new CashRebate(0.8);
			cashContext = new CashContext(cashSuper);
			break;
		}
		std::cout << cashContext->GetResult(money[i]) << std::endl;
		SAFE_DELETE(cashContext)
	}

	//2. 客戶端判斷轉移到CashContext
	for (int i = 0; i < 2; ++i)
	{
		CashContext* cashContext = new CashContext(cashSuperStr[i]);
		std::cout << cashContext->GetResult(money[i]) << std::endl;
		SAFE_DELETE(cashContext)
	}
	return 0;
}