Method returning new instance of class?

[Arthur]

A bit inspired by the decorator discussions, I'm trying to tackle something
I had been avoiding.

Essentially I am trying to create a non-destructive tranformation of an
instance of a class - is one way of putting it.

The way I am currently conceptualizing a solution, what I need is a method
of the class that returns a new instance of the class.

I'm sure this is not new territory.

Suggestions appreciated.

Art