Hello,


when you are inside the visitor the () operator takes two arguments, a
vertex descriptor and a reference to the graph.


So I guess you can use this graph variable to access the property map
for color.


For example I have the following visitor:


<fixed><color><param>7674,0F0D,504E</param>struct</color> SendMsg :
<color><param>7674,0F0D,504E</param>public</color> base_visitor
<<SendMsg>

{

	<color><param>7674,0F0D,504E</param>typedef</color> on_finish_vertex
event_filter;

	

	<color><param>2321,6E6C,2523</param>/* here what the visitor must
do... */</color>

	

	<color><param>7674,0F0D,504E</param>template</color>
<<<color><param>7674,0F0D,504E</param>class</color> Vertex,
<color><param>7674,0F0D,504E</param>class</color> Graph>

		<color><param>7674,0F0D,504E</param>void</color>
<color><param>7674,0F0D,504E</param>operator</color>()(Vertex u,
Graph& g)

	{


			Vertex v = g[u].get_parent_node();

			

			<color><param>7674,0F0D,504E</param>typename</color> graph_traits
<<Graph>::edge_descriptor e = edge(u,v,g).first;


			g[u].send_message( g[v].get_object(), g[e] );

	}	

};


</fixed>I guess in that example, you need to use the g variable with
the color map in order to do what you want... take a look at
"http://www.boost.org/libs/graph/doc/depth_first_search.html" and that
should help you.


I don't know exactly how to that, because I don't know about property
maps, but that would be something like g.color_map[v] = ...


(excuse me for the absolutely wrong syntax... you'd have to use put I
guess)


Jean-Noël


On 7-Mar-05, at 10:37 PM, Stephen Torri wrote:


<excerpt>I have a need to have a graph visitor algorithm similar to
depth first

search. The only difference is that if upon running discover_vertex the

intended operation to be done on the vertex is not done I want the
graph

color value for this position to still be white.


The reason is that the graph I am using the depth first search is a

directed graph with no loops in it. A vertex might have two or more

vertices providing information. If all the information is not there I

want the visitor to try again.


What do I have to do to gain access to the color map inside the visitor

when I am in discover_vertex?


Stephen


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</excerpt>