观察者模式（C++）

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
using namespace std;

class Observer
{
public:
    Observer(){}
    virtual ~Observer(){}
    virtual void run()=0;

protected:
    string _name;
};

class atlete : public Observer
{
public:
    atlete(string name){_name=name;}
    virtual ~atlete(){}
    void run()
    {
        cout<<"atlete "<<_name<<" run"<<endl;
    }
};

class Subject
{
public:
    Subject(){}
    virtual void notify()=0;
    virtual void attach(Observer*)=0;
    virtual void detach(Observer*)=0;

protected:
    vector<Observer*> vec;
};

class referee : public Subject
{
public:
    referee(){}
    virtual ~referee(){}
    void attach(Observer* p)
    {
        vec.push_back(p);
    }
    void detach(Observer* p)
    {
        vec.erase(remove_if(vec.begin(),vec.end(),bind1st(equal_to<Observer*>(),p)));
    }
    void notify()
    {
        cout<<"referee say 'run'"<<endl;
        vector<Observer*>::iterator it;
        for (it=vec.begin();it!=vec.end();it++)
        {
            (*it)->run();
        }
    }
};

int main()
{
    Observer *pat1=new atlete("zhangsan");
    Observer *pat2=new atlete("lisi");
    Observer *pat3=new atlete("wangwu");
    Subject *pre=new referee;

    pre->attach(pat1);
    pre->attach(pat2);
    pre->attach(pat3);
    pre->notify();
    
    cout<<endl;
    pre->detach(pat2);
    pre->notify();

    delete pat1;
    delete pat2;
    delete pat3;
    delete pre;

    system("pause");
    return 0;
}