// src/backend/sgpemv2/history_observer.hh - Copyright 2005, 2006, University
//               of Padova, dept. of Pure and Applied
//               Mathematics
//
// This file is part of SGPEMv2.
//
// This is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// SGPEMv2 is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with SGPEMv2. If not, see http://www.gnu.org/licenses/.


#ifndef HISTORY_OBSERVER_HH
#define HISTORY_OBSERVER_HH 1

namespace sgpem
{
  class History;
  class HistoryObserver;
}

#include <sgpemv2/sgpemv2-visibility.hh>

namespace sgpem
{
  /** \brief Specifies that the object wants to be notified 
   * whenever backend::History changes
   *
   * Observers need to register to an History if they want to be
   * notified.
   * \see History
   */
  class SG_DLLEXPORT HistoryObserver
  {
  public:
    /** \brief Called on an History update 
     */
    virtual void update(const History& changed_history) = 0;
    virtual ~HistoryObserver();

  }
  ; // class HistoryObserver

}//~ namespace sgpem

#endif //HISTORY_OBSERVER_H


