sub match_all_ways {
    my ($string, $regex) = @_;
    my $count;
    my $incr = qr/(?{$count++})/;
    $string =~ /(?:$regex)$incr(?!)/;
    return $count;
}

print match_all_ways("abcdef", qr/..*..*./); # 20
print match_all_ways("abcdef", qr/..*..*./); # undef

##</code><code>##

sub match_all_ways {
    use vars '$count';
    my ($string, $regex) = @_;
    local $count = 0;
    my $incr = qr/(?{$count++})/;
    $string =~ /(?:$regex)$incr(?!)/;
    return $count;
}

##</code><code>##

{
  my $count;
  my $incr = qr/(?{$count++})/;
  sub match_all_ways {
      my ($string, $regex) = @_;
      $count = 0;
      $string =~ /(?:$regex)$incr(?!)/;
      return $count;
  }
}