is_update_from() {
	res="`vercmp $1 $2`"
	case $res in
		'-1'|'0') return 0;;
		'1') return 1;;
	esac
}

## arg 1:  the new package version
## arg 2:  the old package version
post_upgrade() {
	if is_update_from $2 15-1; then
		echo " - pkgtools now uses \$XDG_CONFIG_HOME for all user-specific configuration."
		echo "   run «mv ~/.pkgtools \"\$XDG_CONFIG_HOME/pkgtools\"»"
	fi
	if is_update_from $2 18-1; then
		echo " - newpkg has been rewritten to be completely modular. See here for more info:"
		echo "   http://github.com/Daenyth/pkgtools/commit/2d37197"
	fi
	if is_update_from $2 22-1; then
		echo " - This is the largest release in a long time. This updates all python scripts"
		echo "   to py3k."
		echo " - This version of pkgtools includes a new tool called gem2arch, for automating"
		echo "   ruby gem packaging"
	fi
	if is_update_from $2 24-2; then
		echo " - pkgtools no longer provides the pkgfile command.  This is now provided by the"
		echo "   'pkgfile' package."
		echo " - you may want to clean /var/cache/pkgtools/lists"
	fi
	if is_update_from $2 25-4; then
		echo " - As pactree can print reverse dependency tree since the release of pacman 3.4,"
		echo "   whoneeds is just a small wrapper around pactree now."
	fi
}

## arg 1:  the old package version
post_remove() {
	cat << _EOM
 - You may want to clean /var/cache/pkgtools/lists
_EOM
}