Easy to use macro for creating SFINAE checks.

DefineSFINAECheck.hpp

#include <type_traits> 
// Create our interface
// usage: T1 is the typename, x1 is the variable name.
#define DEFINE_SFINAE_CHECK( NAME, EXPR ) \
template <typename U1> \
struct NAME \
{ \
  using yes = char; \
  using no  = char[2]; \
  template <typename T1>\
  static no& f1(...);\
  template<typename T1> \
  static auto f1(T1 x1) -> decltype( (EXPR), yes() );  \
  enum { value = sizeof(NAME::f1<U1>((std::declval<U1>(), U1()))) \
              == sizeof(NAME::yes) \
       }; \
}

// make a SFINAE check called is_ptr that checks if *x1 is a valid expression.
DEFINE_SFINAE_CHECK(is_ptr, *x1);

#include <iostream>
int main()
{
  static_assert(is_ptr<int *>::value == true, "int * should be a pointer type.");
  static_assert(is_ptr<int>::value == false, "int should not be a pointer type.");
  std::cout << "Success!\n";
}