Parse Function Arguments as well as Command Arguments

examples/parsing_function_args.sh

@@ -0,0 +1,106 @@
+#!/usr/bin/env bash
+
+# demonstrate use of getoptions for parsing function arguments.
+# getoptions was designed for parsing command arguments but works great for functions as well.
+# when a function is called, check to see if the parser function exists.
+# if it does not exist then create it using getoptions and a parser definition.
+# the parser definition is specified internally to the function but it will have global shell scope.
+# 
+
+set -euo pipefail
+
+source ./getoptions.sh
+
+function myfunc() {
+  # declare all function parameters and the helper variable as local variable
+  local my_flag
+  local my_param
+  local my_option
+  # shellcheck disable=SC2034
+  local my_version
+  local my_param2="world"
+  local my_option2
+
+  # declare the helper variable args specified in the parser definition as local
+  local args
+
+  # param2 has a prior value that is not specified in the function call
+  # shellcheck disable=SC2034
+  local param2_current="hello"
+  # shellcheck disable=SC2034
+  local my_option2_current="quick"
+
+  local parser_name="${FUNCNAME[0]}_parser"
+  if [ ! "$(type -t "${parser_name}")" == 'function' ]; then
+
+    myfunc_parser_def() {
+      setup   args plus:true help:usage abbr:true -- "Usage: myfunc [options...] [arguments...]" ''
+      msg -- 'Options:'
+      # shellcheck disable=SC1083
+      flag    my_flag    -f +f --{no-}flag
+      flag    my_verbose -v    --verbose   counter:true init:=0
+      param   my_param   -p    --param     init:="foo" pattern:"foo | bar"
+      param   my_param2  -q    --param2    init:="${my_param2}"
+      option  my_option  -o    --option    validate:number
+      # shellcheck disable=SC1083
+      option  my_option2 -n +n --{no-}option2   init:="missing value" on:"on value" no:"no value"
+      disp    :usage     -h    --help
+      disp    my_version       --version
+    }
+
+    number() {
+      case $OPTARG in (*[!0-9]*)
+        return 1
+      esac
+    }
+    echo "creating parser ${parser_name} from ${parser_name}_def"
+    eval "$(getoptions "${parser_name}_def" "${parser_name}")"
+  fi
+
+  # call the function arg parser
+  "${parser_name}" "${@}"
+  # reset the stack $@ variable to the positional arguments
+  eval "set -- ${args}"
+
+  # shellcheck disable=SC2034
+  readonly my_flag my_param my_option my_version my_param2 my_option2
+
+  #printf "my_flag: %s, my_param: %s, my_option: %s, my_param2: %s, my_option2: %s\n" "${my_flag}" "${my_param}" "${my_option}" "${my_param2}" "${my_option2}"
+
+  echo "  -- arguments begin"
+  local arg
+  for arg in "${@}"; do
+    printf "    %s=%s\n" "${arg}" "${!arg}"
+  done
+  echo "  -- arguments end"
+}
+
+
+echo "-- parameter with default value foo when parameter is not specified"
+myfunc my_param
+
+echo "-- parameter with explicit value bar"
+myfunc -p bar my_param
+
+echo "-- long form parameter with explicit value bar"
+myfunc --param bar my_param
+
+echo "-- option2 when not specified results in default 'missing value'"
+myfunc my_option2
+
+echo "-- option2 explicit on without value results in 'on value'"
+myfunc -n my_option2
+myfunc --option2 my_option2
+
+echo "-- option2 explicit off without value results in 'no value'"
+myfunc +n my_option2
+myfunc --no-option2 my_option2
+
+echo "-- option2 with explicit value results in 'myvalue'"
+myfunc -nmyvalue my_option2
+myfunc --option2=myvalue my_option2
+
+#echo "-- general test"
+myfunc -f --flag -p foo --param bar -o1 --option=2 -n -q "some_value" -- my_param my_flag my_param my_param2 my_option my_option2
+#myfunc -f --flag -p foo --param bar -o1 --option=9 --option2="some_option" -q "some_param" "A" "B" "C"
+#myfunc -f --flag -p foo --param bar -o1 --option=9 -q "some_param" "A" "B" "C"

lib/getoptions_abbr.sh

@@ -44,9 +44,9 @@ getoptions_abbr() {
 	_4 'OPTIND=$((($#+1)/2)) OPTARG=$1; shift'
 	_4 'while [ $# -gt "$OPTIND" ]; do OPTARG="$OPTARG, $1"; shift; done'
 	_4 'set "Ambiguous option: $1 (could be $OPTARG)" ambiguous "$@"'
-	[ "$_error" ] && _4 "$_error" '"$@" >&2 || exit $?'
+	[ "$_error" ] && _4 "$_error" '"$@" >&2 || return $?'
 	_4 'echo "$1" >&2'
-	_4 'exit 1 ;;'
+	_4 'return 1 ;;'
 	_3 '?*)'
 	_4 '[ "$2" = "$3" ] || OPTARG="$OPTARG=$2"'
 	_4 "shift 3; eval 'set -- \"\${OPTARG# }\"' \${1+'\"\$@\"'}; OPTARG= ;;"

lib/getoptions_base.sh

@@ -56,6 +56,7 @@ getoptions() {
 		[ "${1#-}" ] && _rest=$1
 		while loop "$@" && shift; do kv "$1" _; done
 	}
+	_0 "${_def:-$2}() {"
 	_flag() { args '' "$@"; defvar "$@"; }
 	_param() { args 1 "$@"; defvar "$@"; }
 	_option() { args 1 "$@"; defvar "$@"; }
@@ -67,7 +68,6 @@ getoptions() {
 	cmd() { :; }
 	_0 "${_rest:?}=''"
 
-	_0 "${_def:-$2}() {"
 	_1 'OPTIND=$(($#+1))'
 	_1 'while OPTARG= && [ $# -gt 0 ]; do'
 	[ "$_abbr" ] && getoptions_abbr "$@"
@@ -128,7 +128,7 @@ getoptions() {
 		args "$@"
 		_3 "$sw)"
 		code "$1" _4 "echo \"\${$1}\"" "${1#:}"
-		_4 'exit 0 ;;'
+		_4 'return 0 ;;'
 	}
 	_msg() { :; }
 
@@ -188,12 +188,12 @@ getoptions() {
 	_2 'notcmd) set "Not a command: $2" "$@" ;;'
 	_2 '*) set "Validation error ($1): $2" "$@"'
 	_1 'esac'
-	[ "$_error" ] && _1 "$_error" '"$@" >&2 || exit $?'
+	[ "$_error" ] && _1 "$_error" '"$@" >&2 || return $?'
 	_1 'echo "$1" >&2'
-	_1 'exit 1'
+	_1 'return 1'
 	_0 '}'
 
 	[ "$_help" ] && eval "shift 2; getoptions_help $1 $_help" ${3+'"$@"'}
 	[ "$_def" ] && _0 "eval $_def \${1+'\"\$@\"'}; eval set -- \"\${$_rest}\""
-	_0 '# Do not execute' # exit 1
+	_0 '# Do not execute' # return 1
 }