[DGD] Inheriting the same program twice

[Petter Nyström]

I have run into a situation where it would make sense to have an object 
inherit a program twice, at different points in the inheritance tree.

With some ascii-graphic my inheritance tree would look like:

           A
          / \
         B   X
        / \
       X  ...

(Or in words: A inherits B and X, B inherits X.)

I am somehow led to believe this is very bad design, because as my code 
looks right now this shouldn't even compile. That is because I haven't 
defined any of the functions in X in A, so calls to these function in 
objects of type A should be ambiguos, but they are not and it does 
compile. This hints that maybe it doesn't matter if you inherit the same 
program multiple times in one object, it will still only have one data 
space for that program?

I would be happy if someone could tell me some truths on this subject. And 
perhaps also suggest good design alternatives to my problem here. It do 
makes sense for me to have objects of type A to have duplicated and 
separable data fields as defined by X.

Jimorie