effective c++ 27

#include <iostream>

using namespace std;

class Window
{
public:
	Window(){
		cout<<"construct window "<<endl;
	}
	Window(const Window & win){
		cout<<"copy construct window "<<endl;
	}
	virtual void on()
	{
		cerr <<"window "<< this << endl;
	}
};
struct SWindow: public Window
{
public:
	virtual void on()
	{
		(static_cast<Window>(*this)).on();//   Window               
		cerr <<" swindow " << this << endl;
	}
};
int main()
{
	SWindow w;
	w.on();

	Window win1 = w;//        Window       
	Window win(w);
	return 0;
}