CObserver.h

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/* +---------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)               |
   |                          http://www.mrpt.org/                             |
   |                                                                           |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file        |
   | See: http://www.mrpt.org/Authors - All rights reserved.                   |
   | Released under BSD License. See details in http://www.mrpt.org/License    |
   +---------------------------------------------------------------------------+ */
#ifndef  CObserver_H
#define  CObserver_H
 
#include <mrpt/utils/utils_defs.h>
#include <mrpt/utils/mrptEvent.h>
#include <set>
 
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