variadic template

#include <iostream>

using namespace std;

template <typename Op, typename T>
T accumulate(const Op& _operator, const T& a, const T& b){
  return _operator(a, b);
}

template <typename Op, typename T, typename ... Types>
T accumulate(const Op& _operator, const T& head, Types ... tail){
  return accumulate(_operator, head, accumulate(_operator, tail...));
}


class my_operator{
public:
  int operator ()(int a, int b) const{
    return a + b;
  }
};

int main(){
  cout << accumulate(my_operator(), 1, 2, 3, 4, 5, 6, 7, 8, 9, 10) << endl;

  return 0;
}