Introduce python_export_best() to obtain variables for the most preferred Python implementation enabled.

2 files changed, 31 insertions, 2 deletions

diff --git a/eclass/ChangeLog b/eclass/ChangeLog
index c4081f1626b0..753a175e9c03 100644
--- a/eclass/ChangeLog
+++ b/eclass/ChangeLog
@@ -1,6 +1,10 @@
 # ChangeLog for eclass directory
 # Copyright 1999-2012 Gentoo Foundation; Distributed under the GPL v2
-# $Header: /var/cvsroot/gentoo-x86/eclass/ChangeLog,v 1.475 2012/10/29 09:23:58 mgorny Exp $
+# $Header: /var/cvsroot/gentoo-x86/eclass/ChangeLog,v 1.476 2012/10/29 09:25:04 mgorny Exp $
+
+  29 Oct 2012; Michał Górny <mgorny@gentoo.org> python-r1.eclass:
+  Introduce python_export_best() to obtain variables for the most preferred
+  Python implementation enabled.
 
   29 Oct 2012; Michał Górny <mgorny@gentoo.org> python-r1.eclass:
   Add getters for common Python variables.
diff --git a/eclass/python-r1.eclass b/eclass/python-r1.eclass
index 4ce32bd092d9..eb54c74b7d06 100644
--- a/eclass/python-r1.eclass
+++ b/eclass/python-r1.eclass
@@ -1,6 +1,6 @@
 # Copyright 1999-2012 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
-# $Header: /var/cvsroot/gentoo-x86/eclass/python-r1.eclass,v 1.9 2012/10/29 09:23:58 mgorny Exp $
+# $Header: /var/cvsroot/gentoo-x86/eclass/python-r1.eclass,v 1.10 2012/10/29 09:25:04 mgorny Exp $
 
 # @ECLASS: python-r1
 # @MAINTAINER:
@@ -387,3 +387,28 @@ python_foreach_impl() {
 		fi
 	done
 }
+
+# @FUNCTION: python_export_best
+# @USAGE: [<variable>...]
+# @DESCRIPTION:
+# Find the best (most preferred) Python implementation enabled
+# and export given variables for it. If no variables are provided,
+# EPYTHON & PYTHON will be exported.
+python_export_best() {
+	debug-print-function ${FUNCNAME} "${@}"
+
+	[[ ${#} -gt 0 ]] || set -- EPYTHON PYTHON
+
+	local impl best
+	for impl in "${_PYTHON_ALL_IMPLS[@]}"; do
+		if has "${impl}" "${PYTHON_COMPAT[@]}" && use "python_targets_${impl}"
+		then
+			best=${impl}
+		fi
+	done
+
+	[[ ${best+1} ]] || die "python_export_best(): no implementation found!"
+
+	debug-print "${FUNCNAME}: Best implementation is: ${impl}"
+	python_export "${impl}" "${@}"
+}