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

Subject: Re: [Boost-users] [BGL] getting an edge_descriptor of a reverse_graph
From: Alex Hagen-Zanker (ahh34_at_[hidden])
Date: 2011-12-20 12:00:26

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<reverse_graph_edge_descriptor, bool>  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