[gentoo-dev] new eshopts_{push,pop} functions

[Mike Frysinger]

i got tired of copying & pasting the shell option save/restore code, so i
created two helper functions.  am i missing anything before i add to
eutils.eclass ?  i could extend eshopts_pop to take a numeric argument for
number of stack entries to pop, but i dont see much value/use.

# @FUNCTION: eshopts_push
# @USAGE: [options to `set`]
# @DESCRIPTION:
# Often times code will want to enable a shell option to change code behavior.
# Since changing shell options can easily break other pieces of code (which
# assume the default state), eshopts_push is used to (1) push the current shell
# options onto a stack and (2) pass the specified arguments to set.
#
# A common example is to disable shell globbing so that special meaning/care
# may be used with variables/arguments to custom functions.  That would be:
# @CODE
#               eshopts_push -o noglob
#               for x in ${foo} ; do
#                       if ...some check... ; then
#                               eshopts_pop
#                               return 0
#                       fi
#               done
#               eshopts_pop
# @CODE
eshopts_push() {
        # have to assume __ESHOPTS_SAVE__ isn't screwed with
        # as a `declare -a` here will reset its value
        local i=${#__eshopts_save...@]}
        __ESHOPTS_SAVE__[$i]=$-
        [[ $# -eq 0 ]] && return 0
        set "$@" || die "eshopts_push: bad options to set"
}

# @FUNCTION: eshopts_pop
# @USAGE:
# @DESCRIPTION:
# Restore the shell options to the state saved with the corresponding
# eshopts_push call.  See that function for more details.
eshopts_pop() {
        [[ $# -ne 0 ]] && die "eshopts_pop takes no arguments"
        local i=$(( ${#__eshopts_save...@]} - 1 ))
        [[ ${i} -eq -1 ]] && die "eshopts_{push,pop}: unbalanced pair"
        local s=${__ESHOPTS_SAVE__[$i]}
        unset __ESHOPTS_SAVE__[$i]
        set +$-   || die "eshopts_pop: sanity: invalid shell settings !?"
        set -${s} || die "eshopts_pop: sanity: unable to restore saved shell 
settings"
}

and an example of new usage in eutils.eclass:

@@ -1343,16 +1363,15 @@ check_license() {
 
        # here is where we check for the licenses the user already
        # accepted ... if we don't find a match, we make the user accept
-       local shopts=$-
        local alic
-       set -o noglob #so that bash doesn't expand "*"
+       eshopts_push -o noglob # so that bash doesn't expand "*"
        for alic in ${ACCEPT_LICENSE} ; do
                if [[ ${alic} == ${l} ]]; then
-                       set +o noglob; set -${shopts} #reset old shell opts
+                       eshopts_pop
                        return 0
                fi
        done
-       set +o noglob; set -$shopts #reset old shell opts
+       eshopts_pop
 
        local licmsg=$(emktemp)
        cat <<-EOF > ${licmsg}

-mike

signature.asc
Description: This is a digitally signed message part.