Hi All , I've been trying to use a custom structure for describing the various edge properties of a graph. I'm defining a graph as the following struct edge_properties { int capacity ; double weight ; typedef struct edge_properties_tag kind ; // NOT SURE what this does ? }; typedef boost::adjacency_list<listS, vecS, bidirectionalS, property<vertex_name_t, std::string>, edge_properties > Graph; This allows me to create a Graph instance g. I've been trying to retrieve the edge properties via a get call, but have not been able to do so. To retrieve the vertex properties doing the following works property_map<Graph, vertex_name_t>::type v_names ; v_names = get(vertex_name,g) ; But on attempting to do something similar for retrieving the edge properties always fails with the following error message "test.cpp: 75: error: expected primary-expression before ',' token" test.cpp 71: property_map<Graph, edge_properties>::type epr; 72: property_map<Graph, vertex_name_t>::type v_names ; 74: v_names = get(vertex_name,g) ; 75: epr = get(edge_properties,g) ; I've tried various variants but seems to me i'm missing something fundamental in the way boost-graph keeps the edge_properties hidden. Any pointers will be useful. Thanks in advance

On Sun, 14 Mar 2010, Kya Bey wrote:

Hi All ,  I've been trying to use a custom structure for describing the various edge properties of a graph. I'm defining a graph as the following

struct edge_properties {     int         capacity ;      double      weight ;     typedef struct edge_properties_tag kind ;  // NOT SURE what this does ?  };

typedef boost::adjacency_list<listS, vecS, bidirectionalS,                               property<vertex_name_t, std::string>,                               edge_properties > Graph;

This allows me to create a Graph instance g. I've been trying to retrieve the edge properties via a get call, but have not been able to do so. 

It appears that you are trying to use bundled properties. There is information on using them at <URL:http://www.boost.org/doc/libs/1_42_0/libs/graph/doc/bundles.html>. You do not need the kind in your structure in that case.

I've tried various variants but seems to me i'm missing something fundamental in the way boost-graph keeps the edge_properties hidden.  Any pointers will be useful. 

The syntax you want is get(&edge_properties::capacity, g) to get the capacity, and something similar for the weight. -- Jeremiah Willcock