A base class for all graph nodes.

namespace tbb {
namespace flow {

    class graph_node {
        explicit graph_node( graph &g );
        virtual ~graph_node();

} // namespace flow
} // namespace tbb

The graph_node class is a base class for all flow graph nodes. The virtual destructor allows flow graph nodes to be destroyed through pointers to graph_node. For example, a vector< graph_node * > can be used to hold the addresses of flow graph nodes that will need to be destroyed later.