template pass by value or const reference or…?

Question

I can write a templated function this way

template void f(T x) {…}

or this way

template void f(T         


        

Answer 1

Thou shalt not wake the dead, but head a similar problem and here's some example code that shows how to use C++11s type traits to deduce whether a parameter should be passed by value or reference:

#include 
#include 

template
class example
{
    using parameter_type = typename std::conditional::value, key_type, key_type&>::type;

 public:
  void function(parameter_type param)
  {
      if (std::is_reference::value)
      {
          std::cout << "passed by reference" << std::endl;
      } else {
          std::cout << "passed by value" << std::endl;
      }
  }
};

struct non_fundamental_type
{
    int one;
    char * two;
};

int main()
{
  int one = 1;
  non_fundamental_type nft;

  example().function(one);
  example().function(nft);

  return 0;
}

Hope it helps others with a similar issue.