107 lines
3.2 KiB
C
107 lines
3.2 KiB
C
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/*******************************************************************
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* Copyright (c) 2022~2023 XMuli All rights reserved.
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* GitHub: https://github.com/XMuli
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* Description: 观察者模式 Observer Pattern
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* Reference: 情景 → Subject 发送一个消息，然后所有的 Observer A、B、C
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* 都有收到，并且对相同的消息，做出各自不同的操作响应
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* See: https://www.cnblogs.com/suzhou/p/dp16obsvr.html
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******************************************************************/
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#pragma once
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#include <iostream>
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#include <string>
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#include <list>
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using namespace std;
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class Observer { // 观察者
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public:
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virtual void update(string msg) = 0;
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virtual void doSomeThing() = 0;
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protected:
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string m_msg;
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};
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class Subject {
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public:
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Subject() = default;
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virtual ~Subject() = default;
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virtual void addObsvr(Observer* obj) = 0;
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virtual void removeObsvr(Observer* obj) = 0;
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virtual void notify(string msg) = 0;
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};
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//---------------------------------------------------------
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class ConcreteSubject: public Subject {
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public:
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ConcreteSubject() {};
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virtual ~ConcreteSubject() { m_obsvrs.clear(); }
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virtual void addObsvr(Observer* obj) override {
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m_obsvrs.push_back(obj);
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}
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virtual void removeObsvr(Observer* obj) override {
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m_obsvrs.remove(obj);
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}
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virtual void notify(string msg) override {
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for (const auto& it : m_obsvrs)
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it->update(msg);
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for (const auto& it : m_obsvrs)
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it->doSomeThing();
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cout << endl;
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}
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private:
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list<Observer*> m_obsvrs;
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};
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class AObserver : public Observer {
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public:
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void update(string msg) override { m_msg = msg; }
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virtual void doSomeThing() override { cout << "AObserver: 对 " << m_msg << " 进行 A 的操作" << endl; }
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};
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class BObserver : public Observer {
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public:
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void update(string msg) override { m_msg = msg; }
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virtual void doSomeThing() override { cout << "BObserver: 对 " << m_msg << " 进行 B 的操作" << endl; }
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};
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class CObserver : public Observer {
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public:
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void update(string msg) override { m_msg = msg; }
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virtual void doSomeThing() override { cout << "CObserver: 对 " << m_msg << " 进行 C 的操作" << endl; }
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};
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int main()
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{
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AObserver* a = new AObserver();
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BObserver* b = new BObserver();
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CObserver* c = new CObserver();
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ConcreteSubject* concreSubject = new ConcreteSubject();
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concreSubject->addObsvr(a);
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concreSubject->addObsvr(b);
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concreSubject->addObsvr(c);
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concreSubject->notify("messagebox 1");
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concreSubject->removeObsvr(c);
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concreSubject->notify("messagebox 2");
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//a->doSomeThing();
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//b->doSomeThing();
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//c->doSomeThing();
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return 0;
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}
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/*****************************打印结果*******************************
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AObserver: 对 messagebox 1 进行 A 的操作
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BObserver: 对 messagebox 1 进行 B 的操作
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CObserver: 对 messagebox 1 进行 C 的操作
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AObserver: 对 messagebox 2 进行 A 的操作
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BObserver: 对 messagebox 2 进行 B 的操作
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******************************************************************/
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