SG::InitializedReadHandleKey< T > Node1 SG::InitializedReadHandle Key< T > + InitializedReadHandleKey() Node2 SG::ReadHandleKey< T > + ReadHandleKey() + ReadHandleKey() + operator=() # ReadHandleKey() # ReadHandleKey() Node2->Node1 Node3 SG::VarHandleKey - m_storeHandle - m_sgKey - m_hashedKey - m_isEventStore - m_owningHandle + VarHandleKey() + operator=() + assign() + initialize() + initialize() + clid() + key() + empty() + storeHandle() + owningHandle() + isEventStore() + start() + hashedKey() # pythonRepr() - setOwningHandle() - setKey() - updateKey() - parseKey() - updateHandle() Node3->Node2 Node4 Gaudi::DataHandle Node4->Node3