Proxy mode (C++)

definition

Provides a proxy for other objects to control (isolate, use interfaces) access to this object. .

Application Scenario

• In an object-oriented system, direct access to some objects for some reason (for example, the overhead of object creation is very high, or certain operations require security control, or requires out-of-process access, etc.) will bring a lot of problems to the user or the system structure. trouble.
• How to manage/control the unique complexity of operating objects without losing transparency? Adding a layer of indirection is a common solution in software development.

structure

//test.cpp
/****************************************************/
#include "Proxy.h"
int main()
{
    
    
	// 玩魔兽
	ProxyWOW* proxy = new ProxyWOW();
	// 加载
	proxy->load();
	// 充值
	proxy->recharge(1000);
	// 加载
	proxy->load();
	// 退出
	proxy->exit();
	// 清理内存
	delete proxy;
	proxy = nullptr;
	
	return 0;
}

code example

//Proxy.h
/****************************************************/
#ifndef PROXY_H
#define PROXY_H
#include <iostream>
using namespace std;
 
// 抽象游戏类
class Game 
{
    
    
public:
	// 游戏加载
	virtual void load() = 0;
 
	// 游戏退出
	virtual void exit() = 0;
};
 
// 真实游戏类-魔兽世界
class WOW : public Game 
{
    
    
public:
	// 游戏加载
	virtual void load() {
    
    
		cout << "魔兽世界加载。" << endl;
	}
 
	// 游戏退出
	virtual void exit() {
    
    
		cout << "魔兽世界退出。" << endl;
	}
};
 
// 代理类-魔兽代理
class ProxyWOW : public Game 
{
    
    
public:
	// 构造函数
	ProxyWOW() {
    
    
		m_wow = new WOW();
	}
 
	// 析构函数
	virtual ~ProxyWOW() {
    
    
		if (m_wow != nullptr) {
    
    
			delete m_wow;
			m_wow = nullptr;
		}
	}
 
	// 充值时间
	void recharge(int money) {
    
    
		m_time += money / 100;
		cout << "充值：" << money << endl;
		cout << "获得时长：" << m_time << endl;
	}
 
	// 游戏加载
	virtual void load() {
    
    
		cout << "代理启动。" << endl;
		if (m_time > 0) {
    
    
			m_wow->load();
			cout << "游戏时长1小时。" << endl;
			m_time -= 1;
			cout << "剩余时长：" << m_time << endl;
			flag = true;
		}
		else {
    
    
			cout << "剩余游戏时长不足，请充值。" << endl;
			flag = false;
		}
	}
 
	// 游戏退出
	virtual void exit() {
    
    
		if (flag) {
    
    
			m_wow->exit();
			flag = false;
		}
		cout << "代理关闭。" << endl;
	}
 
private:
	bool flag = false;
	int m_time = 0;
	WOW* m_wow;
};


#endif

operation result

Summary

• "Adding a layer of indirection" is a common solution to many complex problems in software systems. In an object-oriented system, using some objects directly will bring many problems, and the proxy object as an indirect layer is a common means to solve this problem.
• The implementation methods and implementation granularity of the specific proxy design pattern vary greatly. Some may implement fine-grained control over a single object, such as copy-on-write technology. proxy.
• Proxy does not necessarily require to maintain the complete consistency of the interface, as long as indirect control can be achieved, sometimes it is acceptable to damage some transparency.