Provisional Dissonance wrote:
Yea, but first the original poster should indicate if
this is what he's
looking for -- I never needed this myself.
Hi, (btw, if possible, it would be nice to know your real name, so that I could write "Hi <your real name>")
At a basic conceptual level, I think of a graph as a data structure composed of nodes and edges. If I'm modeling a family tree, I expect the nodes to be objects of some family-member class. C++ exposes many robust and elegant methods for modeling the family-member - why should I, as a client, have to use property-maps at all?
Hmm, interesting question. In fact, something like typedef graph<City, Road> Road_map; looks quite reasonable to me.
If the node's "index" is related to the object, why would it not be a natural member of the node-type's class?
I don't think "index" should be type of 'City' class.
If, instead, it is a synthesized construct for communication between a graph and the algorithm operating over it, why should the client be responsible for its maintenance instead of the framework? What are the advantages of this approach? What are the disadvantages of simplifying things for the client? This is the type of design issue that I intended to question with my initial post.
I think the biggest problem is: how do you identify vertices? If you use "City&" you'd have some problems: 1. How vertices are really identified? Using operator==? Is it possible to insert two 'City' objects which are equal? If not, how to insure uniqueness? Do we really want 0(log n) lookup on each 'add_vertex'. 2. Even if 'City' objects in a graph are unique, how will add_edge be implemented? Do you need O(log n) lookup to find internal adjacency lists? 3. What's edge, and how it is identified? For example, 'Road' might not contain source/target vertices, but still we need to be able to find source/target vertices. One possible solution that I see is the make vertex_descriptor be always pointer type. It will point at some internal structure but also provide operator* which will return 'City'. Or, maybe, it should be possible to iterate over values of 'City', not only over values of vertex_descriptor. I still don't know if using City to identifiy vertices is feasible. - Volodya