[boost] [graph] out_edges sort

Hi, I would like to visit my graph in a particular order using a dfs visitor. To do this I tried to order the out_edges of each node. I use the std sort function, like this: GraphContainer::out_edge_iterator oe_it, oe_itEnd; boost::tie( oe_it, oe_itEnd ) = boost::out_edges( vd, graph ); std::sort( oe_it, oe_itEnd, OrderEdge<GraphContainer>(graph) ); But it does nothing. It seems that there is an empty operator= on out_edge_descriptor. So, how can I sort the out_edges ? Best regards, Fabien Castan