optfeature.eclass: New eclass with definition from eutils

Signed-off-by: David Seifert <soap@gentoo.org>

1 files changed, 63 insertions, 0 deletions

diff --git a/eclass/optfeature.eclass b/eclass/optfeature.eclass
new file mode 100644
index 000000000000..b0082606cd6d
--- /dev/null
+++ b/eclass/optfeature.eclass
@@ -0,0 +1,63 @@
+# Copyright 1999-2020 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: optfeature.eclass
+# @MAINTAINER:
+# base-system@gentoo.org
+# @BLURB: Advertise optional functionality that might be useful to users
+
+case "${EAPI:-0}" in
+	[0-7]) ;;
+	*)     die "Unsupported EAPI=${EAPI} (unknown) for ${ECLASS}" ;;
+esac
+
+if [[ -z ${_OPTFEATURE_ECLASS} ]]; then
+_OPTFEATURE_ECLASS=1
+
+# @FUNCTION: optfeature
+# @USAGE: <short description> <package atom to match> [other atoms]
+# @DESCRIPTION:
+# Print out a message suggesting an optional package (or packages)
+# not currently installed which provides the described functionality.
+#
+# The following snippet would suggest app-misc/foo for optional foo support,
+# app-misc/bar or app-misc/baz[bar] for optional bar support
+# and either both app-misc/a and app-misc/b or app-misc/c for alphabet support.
+# @CODE
+#	optfeature "foo support" app-misc/foo
+#	optfeature "bar support" app-misc/bar app-misc/baz[bar]
+#	optfeature "alphabet support" "app-misc/a app-misc/b" app-misc/c
+# @CODE
+optfeature() {
+	debug-print-function ${FUNCNAME} "$@"
+
+	local i j msg
+	local desc=$1
+	local flag=0
+	shift
+	for i; do
+		for j in ${i}; do
+			if has_version "${j}"; then
+				flag=1
+			else
+				flag=0
+				break
+			fi
+		done
+		if [[ ${flag} -eq 1 ]]; then
+			break
+		fi
+	done
+	if [[ ${flag} -eq 0 ]]; then
+		for i; do
+			msg=" "
+			for j in ${i}; do
+				msg+=" ${j} and"
+			done
+			msg="${msg:0: -4} for ${desc}"
+			elog "${msg}"
+		done
+	fi
+}
+
+fi