Re: [Boost-users] [BGL] IncidenceGraph and out_edges

Subject: Re: [Boost-users] [BGL] IncidenceGraph and out_edges
From: Andrew Sutton (andrew.n.sutton_at_[hidden])
Date: 2009-06-15 07:18:59

> I'm trying to implement the IncidenceGraph concept for an non-BGL
> undirected graph like datastructure. Following the boost documentation the
> target function used with edges from out_edges(u,g) must give vertices !=
> u.
>
> Can somebody please explain me why this requirement is in BGL! I think it
> can make the adaption very difficult as it requieres to artificially
> orientate undirected edges for each call to out_edges. Any help would be
> much appreciated!
>

I'm not entirely sure. The constraint makes sense if you're building graphs
that don't allow loops, but otherwise, it would not seem to be necessary.
There's a small possibility that the requirement actually stemmed from an
adjacency_list bug that caused problems when deleting loop edges, but the
bug has since been fixed.

I would say: do what you think is right for your own graph structure.

Andrew Sutton
andrew.n.sutton_at_[hidden]