Thanks for your answer! It's good to read that module hierarchy does not have to be pure inheritance. Indeed I try to avoid having excessive depth in my modules hierarchy. I use it only to create compartments for autonomous code. I don't think I would end up with the last situation you described, as it would indeed lead to a high quantity of redundant code. I indeed know about the OO nomenclature and the objects I'm dealing with constitute really a composition. Thanks for the reminder!