You define a member function to create the model _mdl for the whole problem. It calls the functions that create the dimensions, nodes, depots, and visits. This function will be called from the main function.

Add the following code after the comment //Create the model

void RoutingModel::createModel() {
  _mdl = IloModel(_env);
  createDimensions();
  createNodes(_nodePath);
  createDepots(_depotPath);
  createVisits(_visitPath);
}