Command

#include <iostream>



using namespace std;

#define DESTROY_POINTER(ptr) if (ptr) { delete ptr; ptr = NULL; }





class Receiver

{

public:

    void Action1() { cout<<"Receiver::Action1"<<endl; }

    void Action2() { cout<<"Receiver::Action2"<<endl; }

    void Action3() { cout<<"Receiver::Action3"<<endl; }

};





class Command

{

public:

    Command(Receiver* pReceiver) { m_pReceiver = pReceiver; }

    virtual ~Command() { DESTROY_POINTER(m_pReceiver); }

    

    virtual void Execute()=0;



protected:

    Receiver* m_pReceiver;

};



class ConcreteCommandA : public Command

{

public:

    ConcreteCommandA(Receiver* pReceiver) : Command(pReceiver) {}

    

    virtual void Execute() { m_pReceiver->Action1(); }

};



class ConcreteCommandB : public Command

{

public:

    ConcreteCommandB(Receiver* pReceiver) : Command(pReceiver) {}

    virtual void Execute() { m_pReceiver->Action2(); }

};



class ConcreteCommandC : public Command

{

public:

    ConcreteCommandC(Receiver* pReceiver) : Command(pReceiver) {}

    virtual void Execute() { m_pReceiver->Action3(); }

};





class Invoker

{

public:

    Invoker(Command* pCommand) { m_pCommand = pCommand; }

    ~Invoker() { DESTROY_POINTER(m_pCommand); }



    void Request() { m_pCommand->Execute(); }



private:

    Command* m_pCommand;

};







int main(int argc, char *argv[])

{

    Receiver* pReceiver = new Receiver;

    

    Invoker invoker1(new ConcreteCommandA(pReceiver));

    invoker1.Request();



    Invoker invoker2(new ConcreteCommandB(pReceiver));

    invoker2.Request();



    Invoker invoker3(new ConcreteCommandC(pReceiver));

    invoker3.Request();

    

    return 0;

}