C++实现装饰者模式

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多个主题对象，每个主题对象都有三个观察者，感觉有点问题，说不好。有问题请提出来。

 

/*
    观察者模式：定义一种一对多的依赖，让多个观察者同时观察一个对象，当对象状态发生变化时，
    会通知所有它的观察者
*/

#include <iostream>
#include <list>
#include <string>
using namespace std;

class Subject;

class Observer
{
protected:
    string name;
    Subject *subject;
public:
    Observer(Subject *subject, string name)
    {
        this->subject = subject;
        this->name = name;
    }
    virtual void Update()
    {}
};

class Subject
{
    list<Observer*> observers;

public:

    void AddObserver(Observer *observer)
    {
        observers.push_back(observer);
    }

    void RemoveObserver(Observer *observer)
    {
        observers.remove(observer);
    }

    virtual void Notify()
    {
        list<Observer*>::iterator iter = observers.begin();
        for(; iter != observers.end(); iter++)
        {
            (*iter)->Update();
        }
    }
    virtual string  GetState()
    {
        return " ";
    }

    int GetObserverSize()
    {
        return observers.size();
    }
};

class ConcreteSubjectOne:public Subject
{
    string state;
public:

    ConcreteSubjectOne(string state)
    {
        this->state ="One " + state;
    }
    string GetState()
    {
        return this->state;
    }
};

class ConcreteSubjectTwo:public Subject
{
    string state;
public:

    ConcreteSubjectTwo(string state)
    {
        this->state ="Two " + state;
    }
    string GetState()
    {
        return this->state;
    }
};


class ConcreteObserverOne:public Observer
{
public:
    ConcreteObserverOne(Subject *subject, string name)
        :Observer(subject, name)
    {
    }
    void Update()
    {
        cout<<"Observer Type One: "<< name << " subject state is "<< subject->GetState()<<endl;
    }

};

class ConcreteObserverTwo:public Observer
{
public:
    ConcreteObserverTwo(Subject *subject, string name)
        :Observer(subject, name)
    {
    }
    void Update()
    {
        cout<<"Observer Type Two: "<< name << " subject state is "<< subject->GetState()<<endl;
    }

};

int main()
{
    ConcreteSubjectOne *subject_1 = new ConcreteSubjectOne("subject__1");
    ConcreteSubjectTwo *subject_2 = new ConcreteSubjectTwo("subject__2");

    ConcreteObserverOne *observer1  = new ConcreteObserverOne(subject_1, "observer 1");
    ConcreteObserverOne *observer2  = new ConcreteObserverOne(subject_1, "observer 2");
    ConcreteObserverOne *observer3  = new ConcreteObserverOne(subject_1, "observer 3");

    ConcreteObserverTwo *observer4  = new ConcreteObserverTwo(subject_2, "observer 4");
    ConcreteObserverTwo *observer5  = new ConcreteObserverTwo(subject_2, "observer 5");
    ConcreteObserverTwo *observer6  = new ConcreteObserverTwo(subject_2, "observer 6");

    subject_1->AddObserver(observer1);
    subject_1->AddObserver(observer2);
    subject_1->AddObserver(observer3);

    subject_2->AddObserver(observer4);
    subject_2->AddObserver(observer5);
    subject_2->AddObserver(observer6);


    subject_1->Notify();
    subject_2->Notify();

    cout<<subject_1->GetObserverSize()<<endl;
    cout<<subject_2->GetObserverSize()<<endl;

    delete subject_1;
    delete subject_2;

    delete observer6;
    delete observer5;
    delete observer4;
    delete observer3;
    delete observer2;
    delete observer1;

    getchar();
    return 0;
}