#ifndef GEOMETRYOBSERVER_HPP
#define GEOMETRYOBSERVER_HPP
//
// $Id: GeometryObserver.hpp,v 1.2 2002/08/25 20:24:28 melanson Exp $
//
// File: GeometryObserver.hpp
// Purpose: 
// Created:  4-APR-2000   John Hobbs
//
// $Revision: 1.2 $
//
//

// Include files
namespace dgs {

class absObservedGeometer;

// Global definitions
class GeometryObserver {
public:
  // Since this is an observer, every instance must be registered with
  // a geometer.
  GeometryObserver(absObservedGeometer* myGeometer);
  GeometryObserver(const GeometryObserver& rhs);
  GeometryObserver& operator =(const GeometryObserver& rhs);
  virtual ~GeometryObserver();

  /// This returns the state of the update (and changes the state to not updated).
  bool updated();

  /**
     The user may implement this routine.  It is called by update() below.
     If implemented, it should include a call to updated() to reset the
     state to "not updated".
  */
  virtual void user_update();

private:
  friend class absObservedGeometer;

  /// Update is called by the absGeometer when a new geometry shows up
  bool update();

  /// This is set by update, and reset either by is_updated or user_update
  bool d_updated;

  /// The geometer which this observer is watching.  Needed by destructor.
  absObservedGeometer* d_myGeometer;

};

}
#endif //GEOMETRYOBSERVER_HPP