Header files and namespaces :

To continue this tutorial, we need to include the following files, and namespaces.

#include <iostream>
#include <set>
//- - - - - - - - - - - - -
#include <tulip/TlpTools.h>
#include <tulip/Graph.h>
#include <tulip/ObservableGraph.h>
//- - - - - - - - - - - - -

using namespace std;
using namespace tlp;
        	

As said before, we will create a new class that inherits from ObservableGraph. This class will have several functions to be notified when a node or an edge is deleted or added or reversed (edge).

Following is the class GraphObserverTest :

class GraphObserverTest : public GraphObserver {
public:
  GraphObserverTest() {
  }

private:
  void addEdge(Graph * g,const edge e) {
    cout << "edge :" << e.id << " has been added" << endl;
  }
  void delEdge(Graph *,const edge e) {
    cout << "edge :" << e.id << " is about to be deleted" << endl;
  }
  void reverseEdge(Graph *,const edge e) {
    cout << "edge :" << e.id << " is about to be reversed" << endl;
  }
  void addNode(Graph * g,const node n) {
    cout << "node :" << n.id << " has been added" << endl;
  }
  void delNode(Graph *,const node n) {
    cout << "node :" << n.id << " is about to be deleted" << endl;
  }
  void destroy(Graph *g) {
    cout << "graph : " << g->getId() << " is about to be deleted" << endl;
  }
};
        	

Those methods are redefinitions of their homologues in the super class.

Following in the main function with some explanations :

int main(int argc, char **argv) {
  Graph *graph = tlp::newGraph();
        	

Nothing really new here, just the creation of the graph.

  //- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  GraphObserverTest graphObserverTest;
  graph->addObserver(&graphObserverTest);
  //- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        	

We add the instance of our class GraphObserverTest with the function Graph::addObserver .

We then perform some modifications on the graph :

  node n1 = graph->addNode();
  node n0 = graph->addNode();
  edge e0  = graph->addEdge(n0, n1);
  graph->reverse(e0);
  graph->delNode(n0);
  delete graph;
  //- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  return EXIT_SUCCESS;
}
        	

Following is the output of this program :

node :0 has been added
node :1 has been added
edge :0 has been added
edge :0 is about to be reversed
node :0 is about to be deleted 
edge :0 is about to be deleted