observe模式

 

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <map>
#include <list>
#include <algorithm>
using namespace std;
typedef string State;

class SecretaryBase;
//抽象观察者
class CObserverBase {
protected:
    string name;
    SecretaryBase* sub;
public:
    CObserverBase(string strname, SecretaryBase* strsub) {
        name = strname;
        sub = strsub;
    }
    virtual void Update()=0;
};
//具体的观察者，看股票的
class StockObserver: public CObserverBase {
public:
    StockObserver(string strname, SecretaryBase* strsub) :
            CObserverBase(strname, strsub) {
    }
    virtual void Update();
};

//具体观察者，看NBA的
class NBAObserver: public CObserverBase {
public:
    NBAObserver(string strname, SecretaryBase* strsub) :
            CObserverBase(strname, strsub) {
    }
    virtual void Update();
};

//抽象通知者
class SecretaryBase {
public:
    string action;
    vector<CObserverBase*> observers;
public:
    virtual void Attach(CObserverBase* observer)=0;
    virtual void Notify()=0;
};

//具体通知者
class Secretary: public SecretaryBase {
public:
    void Attach(CObserverBase* ob) {
        observers.push_back(ob);
    }
    void Notify() {
        vector<CObserverBase*>::iterator p = observers.begin();
        while (p != observers.end()) {
            (*p)->Update();
            p++;
        }
    }
};

void StockObserver::Update() {
    cout << name << ":" << sub->action << ",不要玩股票了，要开始工作了" << endl;
}
void NBAObserver::Update() {
    cout << name << ":" << sub->action << ",不要看NBA了，老板来了" << endl;
}

int main() {
    SecretaryBase *p = new Secretary(); //创建观察者

    //被观察的对象
    CObserverBase *s1 = new NBAObserver("小李", p);
    CObserverBase *s2 = new StockObserver("小赵", p);
    //加入观察队列
    p->Attach(s1);
    p->Attach(s2);
    //事件
    p->action = "老板来了";
    //通知
    p->Notify();

    return 0;
}