foo()
{
	local var=1

	bar var
}

bar(string ref)
{
	local var=2

	eval "${ref}=3"
}



foo()
{
	local var=1

	bar &var
}

bar(string ref)
{
	local var=2

	!ref=3
}



__ref()
{
	__var=${1}

	case " ${__fn_vars} " in *" ${__var} "*)
		printf '__fn_vars_%d_%s' ${__sp} "${__var}"
		return 0
	;; esac
	eval "__val=\${__${__prev_tu}_static_vars}"
	case " ${__val} " in *" ${__var} "*)
		printf '__fn_vars_%d_%s' ${__sp} "${__var}"
		return 0
	;; esac
}

__derefset()
{
	__var=${1}
	
	case "${__var}" in
		*[!A-Za-z0-9_]*)
			printf 'Error: Invalid reference variable\n' >&2
			exit 1
			;;
		'__fn_vars_'[A-Za-z_]*)
			;;
		*)
			printf 'Error: Invalid reference variable\n' >&2
			exit 1
			;;
	esac

	eval "printf '%s' \${${__var#__fn_vars_}}"
}