So that's why you don't want to derive from it ("isa"), but contain one. Use delegation to expose the calls in the same manner that inheritance would. I do agree that passing the parameter in to create the contained object will be more work since something like that is not handled automatically. So far I've avoided that in my current project, but have speculated on passing the whole parameter list given to 'new' in to the builders for the helper objects, so each pulls the parameters it wants.