代理模式（Proxy）

#include <iostream>
using namespace std;
class Base{
    public:
        virtual void fun()=0;
};
class Derived:public Base{
    public:
/*这里才是真正的实现*/
        virtual void fun()
        {
            cout<<"get"<<endl;
        }
};
class Proxy:public Base{
    private:
/*必须基类指针，为了实现多态，指向真正具有功能的对象*/
        Base *p;
    public:
        Proxy(Base *t):Base()
        {
            p=t;
        }
       /*类间通信*/
        void fun()
        {
            p->fun();
        }
};
int main(void)
{
    Base *d=new Derived();
    Base *p=new Proxy(d);
    p->fun();
    delete d;
    delete p;
    return 0;
}