gistfile1.hpp

class Value
{
  Value() : type_(NIL_TYPE_ID) {}
  
  bool isReal()
  { return type_ == REAL_TYPE_ID; }
  
  // special thing here: anonymous union
  union {
    real_t r;
    int    i;
    const char * c;
  };
  uint type_;
};

// don't pass by value: constructor and destructor code will be called, even for small memory spaces
void compteur(const Value& val)
{
  if (val.isReal())
    compteur_ = val.r;
}