#!/usr/bin/perl

# http://perlmonks.org/?node_id=1166285

use strict;
use warnings;
use Data::Dumper;
sub f {
    my @tmp = "list $_[0]\n" =~ /\G(?:^list\s+|,)(\w+)(?=(?:,\w+)*$)/m
+g;
    print(Dumper(\@tmp));
}
f("foo");
f("foo,bar");
f("foo,bar "); # should fail on this
f("foo, bar"); # should fail on this
[download]

produces

$VAR1 = [
          'foo'
        ];
$VAR1 = [
          'foo',
          'bar'
        ];
$VAR1 = [];
$VAR1 = [];
[download]