#ifndef _ordered_h
#define _ordered_h

class Ordered { // an abstract class

public:

   virtual ~Ordered() =0 ;              // virtual destructor

   virtual Ordered *clone() =0 ;        // make a copy
   virtual int cmp(Ordered *) =0 ;      // compare two Ordered objects

   virtual void print() =0 ;            // print to stdout
   virtual int *id() =0 ;               // run-time typing
} ;

#endif