Re: [Boost-users] BGL: shared_ptr as bundled properties > how to generate properties maps ???

Subject: Re: [Boost-users] BGL: shared_ptr as bundled properties > how to generate properties maps ???
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2010-01-07 09:59:51

On Wed, 6 Jan 2010, Damien Maupu wrote:

> Dear all,
>
> I am using bundled properties when I define my graph.
> The bundled properties are smart pointers to my own class Edge and Vertex.
> I write something like:
> typedef boost::shared_ptr<Vertex> VertexPtr;
> typedef boost::shared_ptr<Edge> EdgePtr;
> typedef adjacency_list<vecS, vecS, directedS, VertexPtr, EdgePtr>    Graph;
>
> Vertex and Edge being my own classes to store information on the vertices and 
> the edges.
> For what I read in the doc, this is the correct, more modern way to do it.
>
> My problem is the following.
> I am trying to use the BGL algorithms and some of them require vertex/edge 
> info to be provide as properties maps.
>
> From http://www.boost.org/doc/libs/1_41_0/libs/graph/doc/bundles.html
> I know it is possible to generate those maps from bundled properties.
>
> It works well if I don't use shared_ptr but cannot compile otherwise.
>
> When using shared_ptr, similarly to the doc, I wrote:
>
> typedef property_map<SearchGraph, float EdgePtr::*>::type WeightMap;
> WeightMap weightMap = get(&EdgePtr::m_cost, *_graph);
>
> m_cost being a public float member of my own class Edge.
>
> I have the following compilation error:
> 'm_cost' : is not a member of 'boost::shared_ptr<T>'
>
> Indeed it is not.
> My question is, I can let the shared_ptr access the member?
> In other world how to deal with bundled properties / properties maps and 
> shared_ptr.
>
> Extra question, could 'm_cost' be a private member of my own class Edge?

Try writing a function that takes an edge descriptor and returns a 
reference to m_cost for that edge (using the bundled property syntax), 
then using the code in 
<URL:http://article.gmane.org/gmane.comp.lib.boost.user/54397> to convert 
that into a property map.

BTW, sorry about referring to this message before I sent it (this is the 
one I was referring to about handling pointers as bundled properties).  I 
thought I had sent it earlier.

-- Jeremiah Willcock