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;
}