////   This file contains the C++ code from Program 5.3 of//   "Data Structures and Algorithms//    with Object-Oriented Design Patterns in C++"//   by Bruno R. Preiss.////   Copyright (c) 1998 by Bruno R. Preiss, P.Eng.  All rights reserved.////   http://www.pads.uwaterloo.ca/Bruno.Preiss/books/opus4/programs/pgm05_03.cpp//#include <typeinfo>Object::~Object ()    {}bool Object::IsNull () const    { return false; }int Object::Compare (Object const& object) const{    if (typeid (*this) == typeid (object))	return CompareTo (object);    else if (typeid (*this).before (typeid (object)))	return -1;    else	return 1;}