Re: [Boost-users] [BGL] graph without parallel edges

From: Douglas Gregor (doug.gregor_at_[hidden])
Date: 2006-02-28 09:24:31

On Feb 28, 2006, at 1:23 AM, Alejandro Aragón wrote:
> Well, it seems now that the problem is fixed.  I was using a directedS
> graph with setS for the OutEdgeListS.  I changed that to  
> undirectedS and
> now edges are not added twice as before.  I thought that setS  
> completely
> discarded parallel edges no matter of the choice of the directivity of
> the graph.  It doesn't make sense to me that you can have a directed
> graph with a disjoint set container that doesn't allow the parallel  
> edge
> behavior.  I think there should be some warning if you use setS with
> directedS right?

I think the Graph library is doing the right thing here. In a  
directed graph, the edges (u, v) and (v, u) are not parallel edges,  
so even with OutEdgeListS=setS you can have both in a graph. By using  
setS, you won't be able to have two edges (u, v) and (u, v).

        Doug