[Boost-users] a question about incremental_component and disjoint_sets.

Hi, I have a question about incremental_component and disjoint_sets. Here is the context: I have a class object initialized with an empty boost::graph. The algorithm incrementally builds the graph with the function add_vertex(graph). At the same time, I have to maintain the connected components of the graph. Here is the question: I know incremental_component.hpp can deal with the case edges are being added. Could it deal with the case that vertices are being added? Especially at the beginning, the graph is empty. And it seems I cannot declare an empty disjoint_sets variable in the class: classe X { ...... protected: //.... some graph typedef std::vector rank; std::vector parent; disjoint_sets ds; ...... }; Here is the compiler error: error C2248: 'disjoint_sets::disjoint_sets ' : cannot access private member declared in class 'boost::disjoint_sets' e:\temp\boost\boost_1_32_0\boost\pending\disjoint_sets.hpp(68) : see declaration of 'disjoint_sets::disjoint_sets' Could anybody help? Thanks a lot. Vivid