On Mon, 5 Oct 2009, Cosimo Calabrese wrote:
Jeremiah Willcock ha scritto:
One issue with it is the case where the vertex or edge descriptor types of the two graphs are the same. You need separate types for "thing from graph 1" and "thing from graph 2"
Yes, it's true.
I thought to use a thing that I haven't never used, that is the 6th template parameter of adjacency_list: GraphProperties.
adjacency_list<EdgeList, VertexList, Directed, VertexProperties, EdgeProperties, *GraphProperties*>
I could define two tags:
struct original_graph_tag { }; struct little_graph_tag { };
and pass these types in the 'original' and 'little' graph, respectively. This could be enough to differentiate the two type of graph, and therefore the descriptors.
That only works if both graphs are adjacency_lists and you have control over the graph types. I would personally just make: template <typename T> struct from_first_graph {T data;}; template <typename T> struct from_second_graph {T data;}; and then have my variants be: boost::variant<from_first_graph<graph_traits<First>::vertex_descriptor>, from_second_graph<graph_traits<Second>::vertex_descriptor>
and the same for edge descriptors. This will disambiguate the types for arbitrary graphs. -- Jeremiah Willcock