////////////////////////////////////////
// test1 -- re-implementation of
// is_convertible and enable_if
////////////////////////////////////////

#include <iostream>
using namespace std;

struct yes {};
struct no { char _c[2]; };

struct any_conversion
{
  template <typename T> any_conversion(T const &);
};

template <typename T>
struct checker
{
  static no check(any_conversion);
  static yes check(T);
};

template <typename From, typename To>
struct is_convertible
{
  static From _from;
  static const bool value =
    sizeof(checker<To>::check(_from)) == sizeof(yes);
};

template <bool Cond>
struct enable_if {};

template <>
struct enable_if<true> 
{
  typedef void type;
};

template <bool Cond>
struct disable_if 
{
  typedef void type;
};

template <>
struct disable_if<true> {};

struct Foo 
{
  Foo() {};

  Foo(Foo const & f) 
  {
    cout << "Copy Constructor." << endl;
  }
  
  template <typename T>
  Foo(T const & t,
      typename enable_if<is_convertible<T,Foo>::value>::type * = 0)
  {
    cout << "Convertible." << endl;
  }

  template <typename T>
  Foo(T const & t,
      typename disable_if<is_convertible<T,Foo>::value>::type * = 0)
  {
    cout << "Not Convertible." << endl;
  }
};

int main() 
{
  Foo f;
  Foo f2(f);
  Foo f3(1);

  return 0;
}