add confutils_require_one

diff --git a/eclass/confutils.eclass b/eclass/confutils.eclass
index 1e6c56baae2430e6cb81264f2f99604e542f1ca7..38f104272a6dcc57b21a4ae4b2ff735f776a0feb 100644 (file)
--- a/eclass/confutils.eclass
+++ b/eclass/confutils.eclass
@@ -1,6 +1,6 @@
 # Copyright 1999-2008 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
-# $Header: /var/cvsroot/gentoo-x86/eclass/confutils.eclass,v 1.21 2008/02/20 13:07:50 hollow Exp $
+# $Header: /var/cvsroot/gentoo-x86/eclass/confutils.eclass,v 1.22 2008/02/27 09:53:04 hollow Exp $
 
 # @ECLASS: confutils.eclass
 # @MAINTAINER:
@@ -38,6 +38,39 @@ confutils_init() {
        fi
 }
 
+# @FUNCTION: confutils_require_one
+# @USAGE: <flag> [more flags ...]
+# @DESCRIPTION:
+# Use this function to ensure exactly one of the specified USE flags have been
+# enabled
+confutils_require_one() {
+       local required_flags="$@"
+       local success=0
+
+       for flag in ${required_flags}; do
+               use ${flag} && ((success++))
+       done
+
+       [[ ${success} -eq 1 ]] && return
+
+       echo
+       eerror "You *must* enable *exactly* one of the following USE flags:"
+       eerror "  ${required_flags}"
+       eerror
+       eerror "You can do this by enabling *one* of these flag in /etc/portage/package.use:"
+
+       set -- ${required_flags}
+       eerror "     =${CATEGORY}/${PN}-${PVR} ${1}"
+       shift
+
+       for flag in $@; do
+               eerror "  OR =${CATEGORY}/${PN}-${PVR} ${flag}"
+       done
+
+       echo
+       die "Missing or conflicting USE flags"
+}
+
 # @FUNCTION: confutils_require_any
 # @USAGE: <flag> [more flags ...]
 # @DESCRIPTION: