前言

我觉得这是最有意思的模式，其中一个动，另外的自动跟着动。发布-订阅，我觉得很巧妙。

代码

头文件

#pragma once
#include<vector>
#include<string>
#include<iostream>// 抽象观察者
class Aobserver
{
public:virtual void update(std::string& updated_state) = 0;
};// 抽象通知者
class Asubject
{
protected:std::vector<Aobserver*> _pObservers;bool whetherRegist(Aobserver* p_observer){for (auto it : _pObservers) {if (it == p_observer) return true;}return false;}public:virtual void registObserver(Aobserver* p_observer) = 0;virtual void detachObserver(Aobserver* p_observer) = 0;virtual void notify(const std::string& teacher_name) = 0;};// 具体通知者
class Csubject1 : public Asubject
{
private:std::string _subjectName;public:Csubject1(const std::string& subject_name) :_subjectName(subject_name) {}// 注册观察者void registObserver(Aobserver* p_observer) override{if (p_observer!=nullptr && whetherRegist(p_observer) == false) {_pObservers.push_back(p_observer);}}void detachObserver(Aobserver* p_observer) override{if (p_observer != nullptr){for (auto it : _pObservers) {if (it == p_observer) {_pObservers.erase(std::remove(_pObservers.begin(),_pObservers.end(),it),_pObservers.end());}}}}void notify(const std::string& teacher_name) override{std::string notify_state = _subjectName + " say: "+ teacher_name +" is coming!";for (auto it : _pObservers) {it->update(notify_state);}}
};// 具体观察者
class Hablee : public Aobserver
{
private:void cancleReading(std::string& updated_state){std::cout << updated_state;std::cout << " you should stop reading" << std::endl;}public:void update(std::string& updated_state) override{this->cancleReading(updated_state);}};class Yuki : public Aobserver
{
private:void canclePlayingGuitar(std::string& updated_state){std::cout << updated_state;std::cout << " you should stop plaing guitar" << std::endl;}public:void update(std::string& updated_state) override{this->canclePlayingGuitar(updated_state);}
};

main.cpp

#include<iostream>
#include"Aobserver.h"int main()
{Csubject1 wzq("wangZhaoQi"); // 通知者Hablee lhb;	wzq.registObserver(&lhb);Yuki wwy;wzq.registObserver(&wwy);wzq.notify("lyj");wzq.notify("xiaoZhang");wzq.detachObserver(&lhb);wzq.notify("lyj");return 0;
}