extensions to settor variables?

[arnold@cc.gatech.edu (Arnold Robbins)]

I may have mentioned this before on this list.  Ksh-93 takes settor
variables two steps further.  You can supply functions that are called
when a variable is a) set, b) referenced, and c) unset.  They are called
discipline functions in ksh.  The syntax is a bit strange and not worth
going through here, but is there interest (on Paul's part in particular)
in seeing something like this in es?

Arnold