On 2011-12-29 15:00:10 +0000, Nicholas Mario Wardhana said:
On 29 December 2011 15:16, Kelvin Chung <kelvSYC@mac.com> wrote:
Suppose I have the following:
template <class T> class Graph { // Adapter class that I use for my purposes typedef typename boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, T> innerGraph; typedef typename boost::graph_traits<innerGraph>::vertex_descriptor VertexDescriptor;
innerGraph G; public: void addVertex(const T& vertex); bool containsVertex(const T& vertex) const;
void addEdge(const T& from, const T& to); // More stuff here };
The intent of this adapter class is to basically abstract out all the mentions of stuff like the descriptors and such. So a good helper function to this end would be a function that retrieves the VertexDescriptor for a given T, if it exists. Is there such a function already in the BGL, or do I have to manage that separately (ie. having an external map)?
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How about storing the descriptor in the T object, by having a member like
VertexDescriptor descriptor;
?
Constant-time retrieval is guaranteed, but then you have to typedef VertexDescriptor in your T. Alternatively, you can have it globally defined.
Wouldn't that impose a concept (or interface) requirement on T? (BTW, what are the current concept requirements for T? Does changing the second template param to boost::setS to disallow parallel edges also implies that T must be less-than comparable?) Or at least, present a chicken-and-egg problem regarding putting my T in a wrapper that also stores the VertexDescriptor? (Not that keeping an external T to VertexDescriptor map is any different, mind you, but at least I know what the external map means for the concept/interface requirements for T.) (Sometimes the language of the BGL documentation confuses me. Especially the fact that "Bundled Properties" seems to be a euphemism of "use a data structure that you like")