废话少说，直接上代码。释义的话，各位看官可自行百度。这个观察者模式的本质，就是将所有观察者对象放进一个list中，发送给观察者的消息，统一使用 NOTIFY_OBSERVER 发给他们。下面就是代码：

#ifndef OBSERVER_H
#define OBSERVER_H
#include <list>
#include "singletonbase.h"
using namespace std;

class CObserver
{
public:
    virtual int OnNotify(int msg1, int msg2, int msg3, int msg4) = 0;
};

class CSubject
{
public:
    virtual int Notify(int msg1, int msg2, int msg3, int msg4) = 0;
    virtual void Attach(CObserver *observer) = 0;
    virtual void Dettach(CObserver *observer) = 0;
};

class ConcreteSubject : public CSubject
{
    REGISTER_SINGLETON(ConcreteSubject)

public:
    __inline int Notify(int msg1, int msg2, int msg3, int msg4)
    {
        int bret = -1, bret1;

        list<CObserver *>::iterator it = m_list_observer.begin();

        for(; it != m_list_observer.end(); it++)
        {
            bret1 = (*it)->OnNotify(msg1, msg2, msg3, msg4);

            if(bret1 != -1)
            {
                bret = bret1;
            }
        }
        return bret;
    }

public:
    __inline void Attach(CObserver *observer)
    {
        m_list_observer.push_back(observer);
    }

    __inline void Dettach(CObserver *observer)
    {
        m_list_observer.remove(observer);
    }

protected:
    list<CObserver*> m_list_observer;
};

#define REGISTER_OBSERVER(observer) \
    GET_SINGLETON_INSTANCE(ConcreteSubject)->Attach(observer)

#define REMOVE_OBSERVER(observer) \
    GET_SINGLETON_INSTANCE(ConcreteSubject)->Dettach(observer)

#define NOTIFY_OBSERVER(param1, param2, param3, param4) \
    GET_SINGLETON_INSTANCE(ConcreteSubject)->Notify(param1, param2, param3, param4)

#endif

 可以看出，这个 NOTIFY_OBSERVER 宏函数，是直接调用派生类的OnNotify函数的。所以，这里要注意多线程的情况。最好就是避免在多线程中使用这个接口。