Re: [Boost-users] boost.graph external properties question.

On Jul 31, 2004, at 9:38 PM, Jeffrey Holle wrote:

HI,

I'm starting a project that uses boost.graph and I'm trying to decide if I should use internal or external properties. My code that implements external properties is like, for example: typedef boost::graph_traits <GraphT>::vertex_descriptor Vertex; typedef std::map VertexData;

My question is:

Given my use of Vertex as a key of a std::map, it needs to be unique. Is this uniqueness quality maintained across different graphs?

No, it is not guaranteed that vertex descriptors from different graphs are distinct. In fact, they will very often be the same: when using adjacency_list with VertexListS = vecS, vertex descriptors are always integers between 0 and num_vertices(g).

That is, can I instanciate 2 GraphT objects and populate both, but maintain only one VertexData container?

Not unless you want to make the key type std::pair. Doug