$qqq = undef();
$www = undef();
$qqq->{qwe} = 123;
printf "'%s'  '%s'  '%s'  '%s'\n",
    $qqq, $www, $qqq->{qwe}, $www->{qwe};

$eee = '';
$rrr = '';
$eee->{asd} = 456;
printf "'%s'  '%s'  '%s'  '%s'\n",
    $eee, $rrr, $eee->{asd}, $rrr->{asd};

$ttt = 'Test';
$yyy = 'Test';
$ttt->{zxc} = 789;
printf "'%s'  '%s'  '%s'  '%s'\n",
    $ttt, $yyy, $ttt->{zxc}, $yyy->{zxc};