Re: [Boost-users] [BGL] getting an edge_descriptor of a reverse_graph

20 Dec 2011


      On 20/12/2011 16:22, Jeremiah Willcock wrote:
...
On Tue, 20 Dec 2011, Alex Hagen-Zanker wrote:
...
I upgraded from boost 1.45 to 1.48 and there are some breaking 
changes related to reverse_graph
The main problem that I encounter is that boost::edge(u ,v, graph) 
returns a edge_descriptor to the graph that underlies reverse_graph, 
rather than reverse_graph itself . The following therefore does not 
compile:
template<typename Graph>
void foo(Graph& graph)
{
 boost::graph_traits<Graph>::edge_descriptor e = boost::edge(0, 1, 
graph).first;
}
That is a bug in that case; please file a ticket about it.  
boost::edge should always return an edge in the graph you call it on.
...
Do you have suggestions how to rewrite foo(Graph& graph)  in order to 
generically work for both plain and reversed graphs? For now I have 
rewritten the boost::edge function in reverse_graph.hpp to return a 
pair  but that does not seem right.
That is the right solution, actually, to match the specification of 
boost::edge.  Please send a patch if you can.
Done: https://svn.boost.org/trac/boost/ticket/6306