#include <functional>
#include <string>
#include <iostream>

class MyClass
{
public:
  template<typename T, typename U>
    auto operator()(T t, U u) const -> decltype(t + u)
    { return t + u; }
};

int main()
{
  auto myObj = std::bind(MyClass(), std::placeholders::_1, "confusing");
  std::cout << myObj(4) << myObj(std::string(" this is ")) << std::endl;    
}