// EqualityComparable concept, requested by IncidenceGraph concept template <typename Graph1, typename Graph2> inline bool operator!=( const typename boost::graph_traits< boost::union_graph<Graph1, Graph2> >::edge_descriptor& left, const typename boost::graph_traits< boost::union_graph<Graph1, Graph2> >::edge_descriptor& right ) { return !( left == right ); }
UG ug( g1, g2 );
graph_traits<UG>::edge_descriptor e1; graph_traits<UG>::edge_descriptor e2;
tie( e1, existence ) = edge( v1, v2, g ); tie( e2, existence ) = edge( v1, v2, g );
e1 != e2; }
I looks like the inequality operator is provided in terms of edge descriptors, but you're actually comparing variants. You may be able to get away with writing something like: template <typename G1, typename G2> bool operator!=( typename graph_traits<union_graph<G1, G2>>::edge_descriptor left, typename graph_traits<union_graph<G1, G2>>::edge_descriptor right) { ... } That should generate an inequality operator over variants, but prevent the template from becoming overly general, since its explicitly "specialized" for your union_graph. Maybe? Andrew Sutton andrew.n.sutton@gmail.com