On Jun 26, 2004, at 5:33 AM, Tim Rowe wrote:

<excerpt>On Fri, 25 Jun 2004 16:53:51 -0500, Doug Gregor wrote:

<excerpt>Exactly. When the type of the vertex list for an adjacency
list is

"vecS", the descriptors are just integers. It tends to make many

things much easier when this is the case!

</excerpt>

Thanks -- is that documented? I couldn't find it.

</excerpt>

*Technically* yes, it's documented, as in "you could find something in
the docs that says that this is the case." Granted, it's an aside in
the description of add_edge for an adjacency_list:

 
"<fontfamily><param>Courier</param><x-tad-bigger>VertexList</x-tad-bigger></fontfamily><fontfamily><param>Times</param><bigger><bigger> selector
is
</bigger></bigger></fontfamily><fontfamily><param>Courier</param><x-tad-bigger>vecS</x-tad-bigger></fontfamily><fontfamily><param>Times</param><bigger><bigger>,
and if either vertex descriptor
</bigger></bigger></fontfamily><fontfamily><param>Courier</param><x-tad-bigger>u</x-tad-bigger></fontfamily><fontfamily><param>Times</param><bigger><bigger>
or
</bigger></bigger></fontfamily><fontfamily><param>Courier</param><x-tad-bigger>v</x-tad-bigger></fontfamily><fontfamily><param>Times</param><bigger><bigger>
(which are integers) has a value greater than the current number of
vertices in the graph, the graph is enlarged so that the number of
vertices is
</bigger></bigger></fontfamily><fontfamily><param>Courier</param><x-tad-bigger>std::max(u,v)
+ 1</x-tad-bigger></fontfamily><fontfamily><param>Times</param><bigger><bigger>."</bigger></bigger></fontfamily>


I'm going to add a more obvious description into the documentation for
our upcoming release. Thanks for pointing out how  confusing this was!


<excerpt> And what about when the type of the vertex list is something
else -- is the type of boost::graph_traits<<G>::vertex_descriptor
available to the user for anything more than declaring variables to
identify vertices?

</excerpt>

Nope, that's it: a vertex descriptor just describes a particular
vertex when coupled with an appropriate graph.


	Doug