>This is a good point to mention current Xerox PARC activities related to
Aspect-Oriented programming (AOP), where various orthogonal issues related
to code-generation are separated into "base" code and "aspect" code.  These
separate (but simple to write) code-specs are "weaved" deterministically
into a single piece of code that handles all of those issues just like a
good programmer would.  ECOOP covers this topic every year, and several
smalltalk implementations have been played with and discussed.  One
disadvantage is that aspects are specified statically, but there are more
dynamic ways that have been explored a little.  One was a smalltalk
implementation that included a MetaObject composition protocol.  I believe
that the implementation had a single MetaMetaObject intercept message-sends
to a given object and then pass the message to various MetaObjects
according to a deterministic strategy that could be dynamically modified.
(Check the ECOOP 99 AOP paper release; I don't have the URL handy).
Anyway, the Xerox group has as its ultimate goal to tackle
exception-handling via aspects or something similar.
>
http://ecoop99.di.fc.ul.pt/techprogramme/workshops.html
	for the ECOOP'99 overview

http://wwwtrese.cs.utwente.nl/aop-ecoop99/
	for the relevant AOP papers, and pointers to the papers of previous AOP
workshops

those should cover the current state of work in that direction.