smart.expression: S Expression for Smart Functions
Description
smart.expression is an S expression for
a smart function to call itself. It is best if you go through it line
by line, but most users will not need to know anything about it.
It requires the primary argument of the smart function to be called
"x".
The list component match.call must be assigned the
value of match.call() in the smart function; this is so
that the smart function can call itself later.