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() = 0;
};

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 = 0; i < m_vecObj.size(); i++)
                {
                        m_vecObj[i]->Update();
                }
        }

        virtual string GetName() = 0;

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 0;
}
//////////////////////////////////
[root@ ~/learn_code/design_pattern/12_observer]$ ./observer       
ConcreteObserverA Get Subject:
ConcreteObserverB Get Subject:
ConcreteObserverA Get Subject: