装饰模式

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

class Component
{
public:
        virtual void Operation() = 0;
};


class ConcreteComponent :public Component
{
        virtual void Operation()
       {
              cout << "具体对象的操作！" << endl;
       }
};

class Decorator :public Component
{
private:
        shared_ptr<Component > _pComponent;
protected:
        shared_ptr<Component > GetComponent()
       {
               return _pComponent;
       }
       
public:
        void SetComponent( shared_ptr<Component > pComponent )
       {
              _pComponent = pComponent;
       }


        virtual void Operation()
       {
               if (_pComponent != NULL)
              {
                     _pComponent->Operation();
              }
       }
};

class ConcreteDecorator1 :public Decorator
{
public:
        virtual void Operation()
       {
               //首先运行原Component的方法，再运行本类的方法
              GetComponent()->Operation();
              cout << "具体装饰对象ConcreteDecorator1" << endl;
       }

};

class ConcreteDecorator2 :public Decorator
{
public:
        virtual void Operation()
       {
              GetComponent()->Operation();
              cout << "具体装饰对象ConcreteDecorator2" << endl;
       }

};

// DecorateMethod.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "Decorator.h"


int _tmain (int argc , _TCHAR * argv [])
{

        //装饰的方法是，首先建造ConcreteComponent对象，
        //然后建造ConcreteDecorator1来装饰ConcreteComponent
        //借助智能指针来实现.
        //最后执行的是最后的装饰类的Operation
        shared_ptr<ConcreteComponent > pConcreteComponent(new ConcreteComponent);

        shared_ptr<ConcreteDecorator1 > pConcreteDecorator1(new ConcreteDecorator1);
       pConcreteDecorator1->SetComponent(pConcreteComponent);
       pConcreteDecorator1->Operation();
       std::cout << std::endl;

        shared_ptr<ConcreteDecorator2 > pConcreteDecorator2(new ConcreteDecorator2);
       pConcreteDecorator2->SetComponent(pConcreteDecorator1);

       pConcreteDecorator2->Operation();
       getchar();
        return 0;
}