Example: maps_observer_pattern_example

C++ example source code:

/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2021, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#include <mrpt/maps/CSimplePointsMap.h>
#include <mrpt/obs/CObservation2DRangeScan.h>
#include <mrpt/obs/stock_observations.h>
#include <mrpt/system/CObserver.h>

#include <iostream>

using namespace mrpt::obs;
using namespace mrpt::maps;
using namespace mrpt::poses;
using namespace mrpt::system;
using namespace std;

// Load a example laser scan:
CObservation2DRangeScan getScan()
{
    CObservation2DRangeScan scan1;
    stock_observations::example2DRangeScan(scan1);
    return scan1;
}

class MyObserver : public mrpt::system::CObserver
{
   protected:
    void OnEvent(const mrptEvent& e) override
    {
        if (e.isOfType<mrptEventMetricMapClear>())
            cout << "[MyObserver] Event received: mrptEventMetricMapClear\n";
        else if (e.isOfType<mrptEventMetricMapInsert>())
            cout << "[MyObserver] Event received: mrptEventMetricMapInsert\n";
        else if (e.isOfType<mrptEventOnDestroy>())
            cout << "[MyObserver] Event received: mrptEventOnDestroy\n";
        else
            cout << "[MyObserver] Event received: Generic mrptEvent \n";
    }
};

// ------------------------------------------------------
//              TestObserverPattern
// ------------------------------------------------------
void TestObserverPattern()
{
    CSimplePointsMap::Ptr map1 = CSimplePointsMap::Create();

    CObservation2DRangeScan obs = getScan();

    // Start observer:
    MyObserver observer;
    observer.observeBegin(*map1);

    // Insert:
    for (int i = 0; i < 3; i++)
        map1->insertObservation(obs);

    // Clear:
    map1->clear();

    // Insert again:
    map1->insertObservation(obs);

    // Destroy
    map1.reset();
}

int main()
{
    try
    {
        TestObserverPattern();

        return 0;
    }
    catch (exception& e)
    {
        cout << "MRPT exception caught: " << e.what() << endl;
        return -1;
    }
    catch (...)
    {
        printf("Another exception!!");
        return -1;
    }
}