> > Am I violating smalltalk style by giving my collections instance
variables?
>
> Yes.  It's much more common to think about (domain object A) *having* a
> collection of (domain object B), rather than *being* a collection.
>
The collection subclass isn't a domain object so much as it describes a
relationship between domain objects.

This collection notifies a listener when its contents have been changed.

What is a more ideal implementation this type of object?

Thank you.