AthenaBaseComps::AthAlgorithmDHUpdate Node1 AthenaBaseComps::AthAlgorithm DHUpdate - m_linkedObjs + AthAlgorithmDHUpdate() + visit() - handle() Node2 IDataHandleVisitor Node2->Node1 Node3 std::unique_ptr< IDataHandle Visitor > + ptr + operator->() Node3->Node1 -m_chain