#!/usr/bin/env perl

use strict;
use warnings;

use Data::Dumper;

my $res_re = qr{ \A [(] ( .* ) [)] \z }x;

my @all_res = (
    ['(x,y,z,etc)', 'maybe other stuff'],
    ['(x,y,z,etc,,abc,,,def)', 'maybe other stuff'],
    ['()', 'maybe other stuff'],
    ['', 'maybe other stuff'],
);

for (@all_res) {
    my @res = @$_;
    print Dumper \@res;
    $res[0] = '()' unless $res[0];

    my $res_wanted = [ split /,/ => ($res[0] =~ $res_re)[0] ];
    $res_wanted = [ '' ] unless @$res_wanted;
    print Dumper $res_wanted;
    print '-' x 60, "\n";
}