mrptEvent.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2018, 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 |
   +------------------------------------------------------------------------+ */
#pragma once
 
#include <mrpt/system/datetime.h>
 
namespace mrpt
{
namespace system
{
class CObservable;
 
/**  The basic event type for the observer-observable pattern in MRPT.
 *   You can sub-class this base class to create custom event types, then
 *    tell between them in runtime with isOfType<T>(), for example:
 * \code
 *   if (e.isOfType<mrptEventOnDestroy>())
 *   {
 *     const mrptEventOnDestroy* ev = e.getAs<mrptEventOnDestroy>();
 *     ev-> ...
 *   }
 * \endcode
 *
 * \sa CObserver, CObservable
 * \ingroup mrpt_system_grp
 */
class mrptEvent
{
   protected:
        /** Just to allow this class to be polymorphic */
        virtual void do_nothing() {}
   public:
        /** Default ctor */
        inline mrptEvent() : timestamp(mrpt::system::now()) {}
        template <class EVENTTYPE>
        inline bool isOfType() const
        {
                return dynamic_cast<const EVENTTYPE*>(this) != nullptr;
        }
 
        template <class EVENTTYPE>
        inline const EVENTTYPE* getAs() const
        {
                return dynamic_cast<const EVENTTYPE*>(this);
        }
 
        template <class EVENTTYPE>
        inline EVENTTYPE* getAsNonConst() const
        {
                return const_cast<EVENTTYPE*>(dynamic_cast<const EVENTTYPE*>(this));
        }
 
        mrpt::system::TTimeStamp timestamp;
 
};  // End of class def.
 
/**  An event sent by any CObservable object (automatically) just before being
 * destroyed and telling its observers to unsubscribe.
 * \ingroup mrpt_base_grp
 */
class mrptEventOnDestroy : public mrptEvent
{
   protected:
        /** Just to allow this class to be polymorphic */
        void do_nothing() override {}
   public:
        inline mrptEventOnDestroy(const CObservable* obj) : source_object(obj) {}
        const CObservable* source_object;
 
};  // End of class def.
 
}  // namespace system
}  // namespace mrpt