求索阁

#include <iostream>
#include <vector>
using namespace std;

//
struct ILight
{
public:
    virtual ~ILight() { }

    virtual void Switch() = 0;
};

class CLightOn : public ILight
{
public:
    virtual ~CLightOn() { }

    virtual void Switch() { cout<<"on to off"<<endl; }
};

class CLightOff : public ILight
{
public:
    virtual ~CLightOff() { }

    virtual void Switch() { cout<<"off to on"<<endl; }
};

class CContext
{
public:
    CContext() { }

    void Switch(ILight *pLight) { pLight->Switch(); }
};

//
void main()
{
    CContext context;

    CLightOn lightOn;
    context.Switch(&lightOn);

}