Checking whether a template argument is a reference [C++03]

Question

I want to check whether a template argument is of reference type or not in C++03. (We already have is_reference in C++11 and Boost).

I made use of SFINAE and the fact that we can't have a pointer to a reference.

Here is my solution

#include <iostream>
template<typename T>
class IsReference {
  private:
    typedef char One;
    typedef struct { char a[2]; } Two;
    template<typename C> static One test(C*);
    template<typename C> static Two test(...);
  public:
    enum { val = sizeof(IsReference<T>::template test<T>(0)) == 1 };
    enum { result = !val };

};

int main()
{
   std::cout<< IsReference<int&>::result; // outputs 1
   std::cout<< IsReference<int>::result;  // outputs 0
}

Any particular issues with it? Can anyone provide me a better solution?

Answer 1

You can do this a lot easier:

template <typename T> struct IsRef {
  static bool const result = false;
};
template <typename T> struct IsRef<T&> {
  static bool const result = true;
};

Answer 2

Years ago, I wrote this:

//! compile-time boolean type
template< bool b >
struct bool_ {
    enum { result = b!=0 };
    typedef bool_ result_t;
};

template< typename T >
struct is_reference : bool_<false> {};

template< typename T >
struct is_reference<T&> : bool_<true> {};

To me it seems simpler than your solution.

However, it was only ever used a few times, and might be missing something.