设计模式——观察者模式（C++实现）

 #include <iostream>
 #include <vector>
 #include <algorithm>
 #include <iterator>
 #include <string>

 using namespace std;

 class STSubject;

 //观察者
 class STObserver
 {
 public:
         virtual void Update() = ;
 };

 class STConcreteObserverA: public STObserver
 {
 public:
         virtual void Update()
         {
                 cout<< "ConcreteObserverA Get Subject: "<< endl;
         }
 };

 class STConcreteObserverB: public STObserver
 {
 public:
         virtual void Update()
         {
                 cout<< "ConcreteObserverB Get Subject: "<< endl;
         }
 };

 //目标
 class STSubject
 {
 public:
         void Attach(STObserver* pstObserver)
         {
                 m_vecObj.push_back(pstObserver);
         }
         void Detach(STObserver* pstObserver)
         {
                 typeof(m_vecObj.begin()) it = find(m_vecObj.begin(), m_vecObj.end(), pstObserver);
                 if (it != m_vecObj.end())
                         m_vecObj.erase(it);
         }
         void Notify()
         {
                 for (size_t i = ; i < m_vecObj.size(); i++)
                 {
                         m_vecObj[i]->Update();
                 }
         }

         virtual string GetName() = ;

 private:
         vector<STObserver*> m_vecObj;
 };

 class STConcreteSubjectA: public STSubject
 {
 public:
         virtual string GetName()
         {
                 return "ConcreteSubjectA";
         }

 };

 int main(int argc, char* argv[])
 {
         STSubject* pstSubjectA = new STConcreteSubjectA();
         STObserver* pstObserverA = new STConcreteObserverA();
         STObserver* pstObserverB = new STConcreteObserverB();

         pstSubjectA->Attach(pstObserverA);
         pstSubjectA->Attach(pstObserverB);

         pstSubjectA->Notify();

         pstSubjectA->Detach(pstObserverB);
         pstSubjectA->Notify();

         return ;
 }
 //////////////////////////////////
 [root@ ~/learn_code/design_pattern/12_observer]$ ./observer
 ConcreteObserverA Get Subject:
 ConcreteObserverB Get Subject:
 ConcreteObserverA Get Subject: