设计模式(5)---代理模式

#include "stdafx.h"
#include <memory>
#include <iostream>

using namespace std;

class Subject
{
public:
    virtual void Request(void) = 0;
};

class RealSubject : public Subject
{
public:
    virtual void Request(void)
    {
        cout << "This is real request." << endl;
    }
};

class Proxy : public Subject
{
public:
    virtual void Request(void)
    {
        if (nullptr == subject_)
        {
            subject_ = make_shared<RealSubject>();
        }
        subject_->Request();
    }
private:
    shared_ptr<Subject> subject_;

};

int main()
{
    shared_ptr<Subject> obj = make_shared<Proxy>();
    obj->Request();
    return 0;
}