I'm wondering if there should ever be inheritance instead of
composition. Can you get away with never using extends and just use
field members. I understand that one can use this as an "is a"
relationship but I think interfaces, having multiples of them allowed
are more appropriate.

Some say that one should use a base class if therre is shared
functionality. I've seen it used very usefully for "deferred"
functionality sometimes but I'm still wondering if that can be done by
composition too. What I mean by deferred is that an abstract class's
non-abstract methods calling abstract ones. With composition, it seems
you'd have the enclosing class merely call the method passing in what
it would need and delegating but somehow, it doesn't seem to fit as
well. I thought perhaps "decorator" and lazy instantiation might be
useful or maybe even listener-/action/event model. This all seems a bit
fuzzy and decorators seem rather powerful but also a bit obscure since
the order of nesting seems so arbitrary. Is there a way to control that
with the pattern better?

Thank you.

John Gagon
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