gistfile1.cpp

#include <iostream>
// implement

template<class T>
void implement(T t){
  t++;
  std::cout << t << std::endl;
}

//interface
template<class T>
void interface(T t){
  implement<T>(t);
}

// specilize
template<class>
void interface<double>(double& t){
  implement<double&>(t);
}

int main(){
  int a = 1;
  double b = 1.0;
  std::cout << a << " " << b << std::endl;
  
  interface(a);
  interface(b);
  
  std::cout << a << " " << b << std::endl;
  
  return 0;
}