How to process command-line args in bash scripts

while [ $# -gt 0 ]; do
case $1 in
--somevar)
SOMEVAR=$2
SOMEVARSTR="--somevar $2"
shift; shift
;;
--othervar)
OTHERVAR=$2
shift; shift
;;
--version)
VERSION=$2
shift; shift
;;
--debug)
DEBUGSTR="--debug"
shift
;;
*)
if [ -n "$TARGET" -o ! -d $1 ]; then
usage
fi
TARGET=$1
shift
;;
esac
done