[boost] [bgl] null vertex

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-07-29 03:34:49

FYI,
I've just comitted a patch which adds the concept of 'null vertex' to BGL. If 
'G' is a graph type, then

    graph_traits<G>::null_vertex()

will return vertex_descriptor which does not refer to any vertex. Of course, 
that value is never returned by add_vertex.

I found this concept usefull in some code of mine, and I recall somebody asked 
for it long time ago. 

- Volodya