CObserver.h

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/* +---------------------------------------------------------------------------+
   |          The Mobile Robot Programming Toolkit (MRPT) C++ library          |
   |                                                                           |
   |                       http://www.mrpt.org/                                |
   |                                                                           |
   |   Copyright (C) 2005-2012  University of Malaga                           |
   |                                                                           |
   |    This software was written by the Machine Perception and Intelligent    |
   |      Robotics Lab, University of Malaga (Spain).                          |
   |    Contact: Jose-Luis Blanco  <jlblanco@ctima.uma.es>                     |
   |                                                                           |
   |  This file is part of the MRPT project.                                   |
   |                                                                           |
   |     MRPT 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.                                   |
   |                                                                           |
   |   MRPT 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 MRPT.  If not, see <http://www.gnu.org/licenses/>.         |
   |                                                                           |
   +---------------------------------------------------------------------------+ */
#ifndef  CObserver_H
#define  CObserver_H

#include <mrpt/utils/utils_defs.h>
#include <mrpt/utils/mrptEvent.h>

namespace mrpt
{
        namespace utils
        {
                class CObservable;

                /** Inherit from this class to get notified about events from any CObservable object after subscribing to it.
                  *
                  *  The main methods in this class are:
                  *   - observeBegin(): To be called to start listening at a given object.
                  *   - OnEvent(): Virtual functions to be implemented in your child class to receive all the notifications. 
                  *
                  *  Note that if custom (child) mrptEvent classes are used, you can tell between them in runtime with "dynamic_cast<>()". 
                  *
                  * \note The pairs CObservable / CObserver automatically notify each other the destruction of any of them, effectively ending the subscription of events.
                  * \ingroup mrpt_base_grp
                  *  \sa CObservable, mrptEvent
                  */
                class BASE_IMPEXP CObserver
                {
                        friend class CObservable;

                public:
                        CObserver();
                        virtual ~CObserver();

                        /** Starts the subscription of this observer to the given object.  \sa observeEnd  */
                        void observeBegin(CObservable &obj);

                        /** Ends the subscription of this observer to the given object (note that there is no need to call this method, since the destruction of the first of observer/observed will put an end to the process
                            \sa observeBegin  */
                        void observeEnd(CObservable &obj);

                private:
                        std::set<CObservable*>  m_subscribed; 
                        void internal_on_event(const mrptEvent &e);

                protected:
                        /** This virtual function will be called upon receive of any event after starting listening at any CObservable object.
                          */
                        virtual void OnEvent(const mrptEvent &e) = 0;

                }; // End of class def.

        } // End of namespace
} // end of namespace
#endif