Re: [Boost-users] [BGL] Problems with remove_vertex

From: Doug Gregor (dgregor_at_[hidden])
Date: 2007-01-29 15:12:11

On Jan 29, 2007, at 2:38 PM, Adrian Boeing wrote:

> Hi Jens,
>
> Unfortunately it's all part of a larger program so I can't easily
> provide a small example.
>
> Yes, I am using the vecS storage:
> typedef
> boost::adjacency_list<boost::vecS,boost::vecS,boost::bidirectionalS,bo 
> ost::property<vertex_prop_t,
> T>,boost::property<edge_prop_t, U>,boost::no_property, boost::listS >
> graph_type;
>
> I'm not sure how to remove the property descriptor, there does not  
> seem
> to be a boost::remove(vertex prop,graph) that I can find anywhere.

Hmmm. So, when one removes a vertex from an adjacency_list with  
VertexListS=vecS, it actually invalidates all of the existing vertex  
descriptors. So simple code like the following causes problems:

        graph_type::vertex_descriptor u = *vertices(g).first;
        graph_type::vertex_descriptor v = *(++vertices(g).first);
        clear_vertex(u, g);
        remove_vertex(u, g);
        adjacent_vertices(v, g); // v has been invalidated

vecS is a tricky beast. I usually recommend avoiding the removal of  
vertices when VertexListS=vecS... it's inefficient and hard to use  
properly.

        Cheers,
        Doug