Hello, I am interested in how boosters think online graph algorithms should be written. I have looked at the connected_components algorithm and feel that it breaks some of the ideas behind generic programming. For example, consider the following:

typedef adjacency_list <vecS, vecS, undirectedS> Graph; Graph G(6); add_edge(0, 1, G); add_edge(1, 4, G);

// create the disjoint-sets structure, which requires // rank and parent vertex properties ... initialize_incremental_components(G, ds); incremental_components(G, ds);

generic_algorithm_which_adds_edges(G);

At this point, the connected_components data structures may be out-of-sync. Now, I suppose that we could write a wrapper class which looked like a "Graph" and provides its own add_edge to update "ds" correctly. However, this seems overly cumbersome. It strikes me that a better way of doing this would be to use an abstract base class, like so:

template<class T, ...> class connected_components : public T { ... };

template<class T> pair<T::edge_descriptor, bool> add_edge(connected_components<T>::vertex_descriptor t, ...) { // do stuff return add_edge(static_cast<T::vertex_descriptor>(t), ...); }

Thus, we supply "Graph" as the base class and can then safely pass it to "generic_algorithm_which...". So, does anyone know of any reasons not to do this? Cheers, David J. Pearce