//
//   This file contains the C# code from Program 5.2 of
//   "Data Structures and Algorithms
//    with Object-Oriented Design Patterns in C#"
//   by Bruno R. Preiss.
//
//   Copyright (c) 2001--2002 by Bruno R. Preiss, P.Eng.  All rights reserved.
//
//   http://www.brpreiss.com/books/opus6/programs/pgm05_02.txt
//
public abstract class ComparableObject : IComparable
{
    public static bool operator ==(ComparableObject c, object o)
    {
	if ((object)c == null || (object)o == null)
	    return (object)c == (object)o;
	else
	    return c.Compare(o) == 0;
    }

    public static bool operator !=(ComparableObject c, object o)
    {
	if ((object)c == null || (object)o == null)
	    return (object)c != (object)o;
	else
	    return c.Compare(o) != 0;
    }

    public static bool operator <(ComparableObject c, object o)
	{ return c.Compare(o) < 0; }

    public static bool operator >(ComparableObject c, object o)
	{ return c.Compare(o) > 0; }

    public static bool operator <=(ComparableObject c, object o)
	{ return c.Compare(o) <= 0; }

    public static bool operator >=(ComparableObject c, object o)
	{ return c.Compare(o) >= 0; }
    // ...
}