编译时多态

#include "stdafx.h"
#include <iostream>
using namespace std;

template <class T>
class B1
{
public: 
	void SayHi() 
	{
		T* pT = static_cast<T*>(this);   // HUH?? I‘ll explain this below

		pT->PrintClassName();
	}

	void PrintClassName() { cout << "This is B1"<<endl; }
};

class D1 : public B1<D1>
{
	// No overridden functions at all
};

class D2 : public B1<D2>
{
public:
	void PrintClassName() { cout << "This is D2"<<endl; }
};

int main()
{
	D1 d1;
	D2 d2;

	d1.SayHi();    // prints "This is B1"
	d2.SayHi();    // prints "This is D2"

	system("pause");

	return 0;
}