[gentoo-dev] evar_push/pop helpers

[Mike Frysinger]

simple set of helpers to save/restore a variable in a limited section of code

you can see an example of it in action at the end of the file where i need to
tweak epatch (and no, doing `LC_COLLATE=C set -- ....` does not work).
-mike

--- eutils.eclass	22 May 2013 05:10:29 -0000	1.421
+++ eutils.eclass	2 Jun 2013 03:00:46 -0000
@@ -146,6 +146,77 @@ estack_pop() {
 	eval unset ${__estack_name}\[${__estack_i}\]
 }
 
+# @FUNCTION: evar_push
+# @USAGE: <variable to save> [more vars to save]
+# @DESCRIPTION:
+# This let's you temporarily modify a variable and then restore it (including
+# set vs unset semantics).  Arrays are not supported at this time.
+#
+# For example:
+# @CODE
+#		evar_push LC_ALL
+#		export LC_ALL=C
+#		... do some stuff that needs LC_ALL=C set ...
+#		evar_pop
+#
+#		# You can also save/restore more than one var at a time
+#		evar_push BUTTERFLY IN THE SKY
+#		... do stuff with the vars ...
+#		evar_pop     # This restores just one var, SKY
+#		... do more stuff ...
+#		evar_pop 3   # This pops the remaining 3 vars
+# @CODE
+evar_push() {
+	local var val
+	for var ; do
+		[[ ${!var+set} == "set" ]] \
+			&& val=${!var} \
+			|| val="${___ECLASS_ONCE_EUTILS}"
+		estack_push evar "${var}" "${val}"
+	done
+}
+
+# @FUNCTION: evar_push_set
+# @USAGE: <variable to save> [new value to store]
+# @DESCRIPTION:
+# This is a handy shortcut to save and temporarily set a variable.  If a value
+# is not specified, the var will be unset.
+evar_push_set() {
+	local var=$1
+	evar_push ${var}
+	case $# in
+	1) unset ${var} ;;
+	2) eval ${var}=\$2 ;;
+	*) die "${FUNCNAME}: incorrect # of args: $*" ;;
+	esac
+}
+
+# @FUNCTION: evar_pop
+# @USAGE: [number of vars to restore]
+# @DESCRIPTION:
+# Restore the variables to the state saved with the corresponding
+# evar_push call.  See that function for more details.
+evar_pop() {
+	local cnt=$1
+	case $# in
+	0) cnt=1 ;;
+	1)
+		: ${cnt:=bad}
+		[[ -n ${cnt//[0-9]} ]] && die "${FUNCNAME}: first arg must be a number: $*"
+		;;
+	*) die "${FUNCNAME}: only accepts one arg: $*" ;;
+	esac
+
+	local var val
+	while (( cnt-- )) ; do
+		estack_pop evar val || die "${FUNCNAME}: unbalanced push"
+		estack_pop evar var || die "${FUNCNAME}: unbalanced push"
+		[[ ${val} == "${___ECLASS_ONCE_EUTILS}" ]] \
+			&& unset ${var} \
+			|| eval ${var}=\${val}
+	done
+}
+
 # @FUNCTION: eshopts_push
 # @USAGE: [options to `set` or `shopt`]
 # @DESCRIPTION:
@@ -344,8 +415,11 @@ epatch() {
 		local EPATCH_SUFFIX=$1
 
 	elif [[ -d $1 ]] ; then
-		# Some people like to make dirs of patches w/out suffixes (vim)
+		# We have to force sorting to C so that the wildcard expansion is consistent #471666.
+		evar_push_set LC_COLLATE C
+		# Some people like to make dirs of patches w/out suffixes (vim).
 		set -- "$1"/*${EPATCH_SUFFIX:+."${EPATCH_SUFFIX}"}
+		evar_pop
 
 	elif [[ -f ${EPATCH_SOURCE}/$1 ]] ; then
 		# Re-use EPATCH_SOURCE as a search dir