Recursive objects decoration

Problem wording :

Design a system enabling to display visual objects on a screen. A visual object can be composed with one or more texts or images. If needed, the system must allow to add to this object a vertical scrollbar, an horizontal scrollbar, an edge and a menu (these additions may be cumulated).

Optimal solution :

Static diagram :

In this solution, if we add a new decoration, there is no code modification. Moreover, the decorators are able to decorate themselves.

Alternative solution 1 :

Static diagram :

Except for adding a new Decorator, this solution is not so bad

Click here to see the spoiled pattern deduced from this alternative solution

Alternative solution 2 :

Static diagram :

In this solution, there is no extensibility possibilities, no maximal factorisation between decorators and objects to decorate, and a decorator can't be decorated by another decorator

Click here to see the spoiled pattern deduced from this alternative solution

Alternative solution 3 :

Static diagram :

In this solution, we cannot manage the decoration during the execution.

Click here to see the spoiled pattern deduced from this alternative solution

Alternative solution 4 :

Static diagram :

In this solution, it is not possible to add or to remove a object to decorate withtout doing code mofication. The factorisation between decorators and objects to decorate is not maximal. Moreover, a decorator cannot be decorated by another decorator.

Click here to see the spoiled pattern deduced from this alternative solution