1 files changed, 42 insertions, 0 deletions
diff --git a/pym/portage/package/ebuild/_config/helper.py b/pym/portage/package/ebuild/_config/helper.py
new file mode 100644
index 000000000..00e2dfabc
--- /dev/null
+++ b/pym/portage/package/ebuild/_config/helper.py
@@ -0,0 +1,42 @@
+# Copyright 2010 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+__all__ = (
+	'ordered_by_atom_specificity',
+)
+
+from portage.dep import best_match_to_list
+
+def ordered_by_atom_specificity(cpdict, pkg):
+	"""
+	Return a list of matched values from the given cpdict,
+	in ascending order by atom specificity. The rationale
+	for this order is that package.* config files are
+	typically written in ChangeLog like fashion, so it's
+	most friendly if the order that the atoms are written
+	does not matter. Therefore, settings from more specific
+	atoms override those of less specific atoms. Without
+	this behavior, settings from relatively unspecific atoms
+	would (somewhat confusingly) override the settings of
+	more specific atoms, requiring people to make adjustments
+	to the order that atoms are listed in the config file in
+	order to achieve desired results (and thus corrupting
+	the ChangeLog like ordering of the file).
+	"""
+
+	results = []
+	keys = list(cpdict)
+
+	while keys:
+		bestmatch = best_match_to_list(pkg, keys)
+		if bestmatch:
+			keys.remove(bestmatch)
+			results.append(cpdict[bestmatch])
+		else:
+			break
+
+	if results:
+		# reverse, so the most specific atoms come last
+		results.reverse()
+
+	return results