C++ 멤버템플릿의 특수화에 관한 마법같은(?) 코드

#include <iostream>
 
template<typename T>
struct identity { typedef T type; };
 
template<typename T>
class CConstraint
{
	public:
		template <typename TL>
			void Verify(int position, int* constraints);
 
	private:
		template<typename TL>
			void Verify(int, int*, identity<TL>);
		void Verify(int, int*, identity<int>);
		void Verify(int, int*, identity<long>);
};
 
 
template<typename T>
template <typename TL>
void CConstraint<T>::Verify(int position, int* constraints)
{
	Verify(position, constraints, identity<TL>());
}
 
template<typename T>
template<typename TL>
void CConstraint<T>::Verify(int, int*, identity<TL>)
{
	std::cout << "111" << std::endl;
}
 
template<typename T>
void CConstraint<T>::Verify(int, int*, identity<int>)
{
	std::cout << "222" << std::endl;
}
 
template<typename T>
void CConstraint<T>::Verify(int, int*, identity<long>)
{
	std::cout << "333" << std::endl;
}
 
 
int main()
{
	int arg = 100;
 
	CConstraint <char> obj;
	obj.Verify<int>(100, &arg);   //222
	obj.Verify<char>(100, &arg);  //111
	obj.Verify<long>(100, &arg);  //333
 
	CConstraint <long> obj2;      
	obj2.Verify<int>(100, &arg);  //222
	obj2.Verify<char>(100, &arg); //111
	obj2.Verify<long>(100, &arg); //333
 
	return 0;
}