Hi all, I am wrapping the Boost Graph Library with a thin class, and I am having a problem in retrieving the edge. I use a mechanism similar to the one in here: http://stackoverflow.com/questions/3100146/adding-custom-vertices-to-a-boost... For testing, I add two vertices (suppose pNode1 and pNode2) successfully, and they can be retrieved as well by passing in their vertex descriptors. However, this is not the case for the edges: when I add an edge from pNode1 to pNode2, the edge is correctly stored as the out_edge of pNode1, but when I retrieve the edge using its edge descriptor, which is the (valid) return value of the add_edge() function, the pointer value is NULL. Also, when I debug the code, I find that inside the graph, there are two variables m_edges and m_vertices. The m_vertices correctly contains two vertex descriptors, but the m_edges is empty. So, do I make a mistake here? I have been looking for some information in Boost's archive and other sources (StackOverflow, ...), but so far haven't found anything helpful. I include a snippet at the end of this e-mail. I am using Visual Studio 2008 SP1 on Windows Vista SP2, and Boost 1.44.0 (haven't upgraded yet to 1.45, but the latter doesn't seem to address this issue). Thank you! Best regards, Nicholas Mario Wardhana //--------------------------- snippet ----------------------------- template <class NodeData, class EdgeData> class BoostGraphWrapper : public Graph<NodeData, EdgeData> { typedef boost::adjacency_list<boost::listS, boost::listS, boost::directedS, Node<NodeData>*, Edge<NodeData, EdgeData>*, boost::listS> BoostGraph; typedef typename boost::graph_traits<BoostGraph>::vertex_descriptor BoostVertexDescriptor; typedef typename boost::graph_traits<BoostGraph>::edge_descriptor BoostEdgeDescriptor; //... public: void AddNode(Node<NodeData>* pNode); Edge<NodeData, EdgeData>* AddEdge(Node<NodeData>* pNode1, Node<NodeData>* pNode2); //... private: BoostGraph m_graph; //... }; template <class NodeData, class EdgeData> void BoostGraphWrapper<NodeData, EdgeData>::AddNode(Node<NodeData>* pNode) { Graph<NodeData, EdgeData>::AddNode(pNode); // 1. Get the descriptor BoostVertexDescriptor vertexDescriptor = boost::add_vertex(m_graph); // 2. Fill with the node m_graph[vertexDescriptor] = pNode; // ... } template <class NodeData, class EdgeData> Edge<NodeData, EdgeData>* BoostGraphWrapper<NodeData, EdgeData>::AddEdge( Node<NodeData>* pNode1, Node<NodeData>* pNode2 ) { Graph<NodeData, EdgeData>::AddEdge(pNode1, pNode2); // 1. Get vertex descriptors of the nodes BoostVertexDescriptor vertexDescriptor1 = GetBoostVertexDescriptor(pNode1); BoostVertexDescriptor vertexDescriptor2 = GetBoostVertexDescriptor(pNode2); Node<NodeData>* tempNode = m_graph[vertexDescriptor1]; Node<NodeData>* tempNode2 = m_graph[vertexDescriptor2]; // 2. Add an empty edge BoostEdgeDescriptor edgeDescriptor; bool inGraph = false; boost::tie(edgeDescriptor,inGraph) = boost::add_edge(vertexDescriptor1, vertexDescriptor2, m_graph); if(!inGraph) { return NULL; } assert(BoostEdgeSize() == 1); // successful // 3. Fill the edge with the vertices Edge<NodeData, EdgeData>* temp = m_graph[edgeDescriptor]; assert(NULL != temp); // fails here //.... return pEdge; } void SomeFunction() { BoostGraphWrapper<int, int> graphWrapper; Node<int>* pNode1 = new Node<int>(); Node<int>* pNode2 = new Node<int>(); Edge<int, int>* pEdge; graphWrapper.AddNode(pNode1); graphWrapper.AddNode(pNode2); pEdge = graphWrapper.AddEdge(pNode2, pNode1); // fails here }