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Asked: 2026-06-01T14:12:38+00:00

Edit: I can use Actionscript 3.0 and/or Java I have a bit of a

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Edit: I can use Actionscript 3.0 and/or Java

I have a bit of a problem with the decorator class. I want to be able to decorate a subclass of a subclass of the abstract class.

To clarify; I have the abstract weapon class, which an abstract sword class extends. Then, finally a concrete long sword class extends it. I want to be able to decorate the long sword class.

                                   Weapon <-------------Enchant "Decorator
                                     /\                  /   \
                                    /  \        "+3 damage"|"Paralyze"
                                   /    \                  V
"Abstract Components":       Sword    |    Axe    "Concrete Decorators" 
                              / \         /    \
                             /   \       /      \
"Concrete Components": LongSword|Short RedAxe| WarAxe "Apply Decorators Here"

Currently all the books I’ve read about design patterns deals with “one layer” Decorations, e.g:

                                        Weapon <-------------Enchant "Decorator
                                         /\                  /   \
                                        /  \        "+3 damage"|"Paralyze"
                                       /    \                  V
  "Concrete components already":    Sword | Axe      "Concrete Decorators"
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1 Answer

  1. Editorial Team

    In static languages like Java, C++ and (I presume) C#, you can’t create a decorator for a class and use it to decorate subclasses of that class. Well you can, but the effect is to hide the functionality of the subclass.

    I guess what you want is to be able to mix-and-match decorators, where each decorator could be for the object’s class or one of its ancestors.

    In the dynamic languages e.g., perl and ruby, you can define or redefine an individual method of an individual object, and you could theoretically use this to peform decoration on subclasses.

    Assuming you’re constrained by a static language, my suggestion is this: For each kind of enchantment your want to have, create a Modifier base class or interface, and then create concrete classes for each enchantment. Then in each object, have a list of modifiers of each class/interface, and run through them as necessary to, say, calculate damage.

    The closest analogous patterns are Strategy or Template Method.

    I have translated your question in my mind to “How would one implement the item modifier system used in the Diablo games?”. There are many issues to consider – saving and restoring state, and interactions between modifiers, are just two that occur to me now.

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