//Purpose:
//  Prototype d version of boost::mpl::set
//
  class
bool_
  ( bool TrueFalse
  )
{
}
  class
set
  (
  )
{
}
  class
set
  ( Head
  , Tail...
  )
  : set!(Tail) //needed if specialization of has_key_tester to work.
{
}
  
  bool_!(true)
has_key_tester
  ( Head
  , Tail...
  )
  /*Modelled after
   * void print(T, A...)(T t, A a)
   *at http://www.digitalmars.com/d/variadic-function-templates.html
   */
  ( set!(Head,Tail)
  )
{
    return new bool_!(true);
}
  bool_!(false)
has_key_tester
  ( Head
  )
  ( set!()
  )
{
    return new bool_!(false);
}

  class 
not_member
{}
  
void test()
{
    auto set_int_float=new set!(int,float);
    auto set_empty=new set!();
    set_empty=set_int_float;//check that set_empty is superset of set_int_float
    {
        bool_!(true) result=has_key_tester!(int)(set_int_float);
    }
    {
        bool_!(false) result=has_key_tester!(not_member)(set_empty);
    }
    {
        bool_!(false) result=has_key_tester!(not_member)(set_int_float);
    }
}