observer.h

c++程序

//Observer.h
#ifndef _OBSERVER_H_ 
#define _OBSERVER_H_

#include "Subject.h"
#include <string> 
using namespace std;

typedef string State;

class Observer 
{ 
public: 
	virtual ~Observer();
	virtual void Update(Subject* sub) = 0;
	virtual void PrintInfo() = 0;
protected: 
	Observer();
	State _st;
private:
};

class ConcreteObserverA:public Observer 
{ 
public: 
	virtual Subject* GetSubject(); 
	ConcreteObserverA(Subject* sub);
	virtual ~ConcreteObserverA();
	//传入Subject作为参数，这样可以让一个View属于多个的Subject。 
	void Update(Subject* sub);
	void PrintInfo();
protected:
private: 
	Subject* _sub;
};

class ConcreteObserverB:public Observer 
{ 
public: 
	virtual Subject* GetSubject(); 
	ConcreteObserverB(Subject* sub);
	virtual ~ConcreteObserverB();
	//传入Subject作为参数，这样可以让一个View属于多个的Subject。 
	void Update(Subject* sub);
	void PrintInfo();
protected:
private: 
	Subject* _sub;
};

#endif