#include <utility>
#include <iostream>

template<typename fun, typename... Ts>
class Dispatcher {
public:
  void dispatch(int x, Ts&& ...args) {
    if (x > 0)
      call<int>(std::forward<Ts>(args)...);
    else
      call<double>(std::forward<Ts>(args)...);
  }

protected:
  template<typename T>
  void call(Ts&& ...args) {
    throw std::runtime_error("Not implemented");
  }
};

class bla {};

template<> template<typename T>
void Dispatcher<bla, int, char, double>::call(int&& a, char&& b, double&& c) {
  std::cout << typeid(T).name() << " " << a << " " << b << " " << c << std::endl;
}

main() {
  std::cout << "main()" << std::endl;
  Dispatcher<bla, int, char, double> d;
  d.dispatch(5, 1, 'a', 5.5);
  d.dispatch(-5, 1, 'a', 5.5);
}