recursive INCLUDERC tricks - dirname.rc

For a number of weeks, the following comment from my "spamcheck" has
been bothering me
   # needs to be set for INCLUDERC.  Is there a way to get it from $_ ?
   SPAMCHECK_RCDIR=${SPAMCHECK_RCDIR:-$RCDIR/spamcheck}
that is I want to do
   this_rcfile=$_
   SPAMCHECK_RCDIR=`dirname $this_rcfile`
but without having to leave procmail.  Well, today I figured out how
to do this by using a recursive INCLUDERC file.  Here's dirname.rc
  lastdirname=${lastdirname:-"/"}

  dir_re="[^/]+"
  regexp=${regexp:-"(^/)?$dir_re"}
  :0
  * $ PATHNAME ?? ()\/$regexp
  {
    lastdirname=$dirname
    dirname=$MATCH

    regexp=$regexp/$dir_re
    INCLUDERC=$_
  }
  :E
  {
    DIRNAME=$lastdirname
    lastdirname=
    dirname=
    regexp=
  }

And a few simple test cases...
  RCDIR=$HOME/.procmail

  PATHNAME=/foo/bar/baz/foobar.baz
  INCLUDERC=$RCDIR/dirname.rc
  TMP=`dirname $PATHNAME`
  LOG="$PATHNAME: $DIRNAME <-> $TMP
  "

  PATHNAME=/foo
  INCLUDERC=$RCDIR/dirname.rc
  TMP=`dirname $PATHNAME`
  LOG="$PATHNAME: $DIRNAME <-> $TMP
  "

  PATHNAME=foo/bar/baz/foobar.baz
  INCLUDERC=$RCDIR/dirname.rc
  TMP=`dirname $PATHNAME`
  LOG="$PATHNAME: $DIRNAME <-> $TMP
  "
It seems like things such as this would be a lot easier of procmail
had a LIGHTER variable which would be set to the matching text before
the \/ token.

   Dan
------------------- message is author's opinion only ------------------
J. Daniel Smith <DanS(_at_)bristol(_dot_)com>        
http://www.bristol.com/~DanS
Bristol Technology B.V.                   +31 33 450 50 50, ...51 (FAX)
Amersfoort, The Netherlands               {info,jobs}(_at_)bristol(_dot_)com