This code is broken, and only does the right thing because of the 1/2/3 nature of the example. Use this patch (only a few lines have changed, so it should be human readable) to get it to work for all cases.

RCS file: /home/perl/tools/Cartesian.pm,v
retrieving revision 1.2
diff -r1.2 Cartesian.pm
30c30,31
<     my $sizes = [];
---
>     my $div = [];
>     my $mod = [];
33,34c34,36
<         push @$sizes, scalar(@$lref);
<         $total *= $sizes->[-1];
---
>         push @$div, $total;
>         push @$mod, scalar(@$lref);
>         $total *= $mod->[-1];
37,38c39,42
<     $self->{sizes} = $sizes;
<     $self->{count} = $total;
---
>     $self->{div} = $div;
>     $self->{mod} = $mod;
>     $self->{total} = $total;
>     $self->{count} = 0;
44,45c48,49
<     my $c = $self->{count}--;
<     return undef  unless $c;
---
>     my $c = $self->{count}++;
>     return undef if ($c == $self->{total});
48c52
<         push @$ret, $self->{arr}->[$i]->[$c % $self->{sizes}->[$i]];
---
>         push @$ret, $self->{arr}->[$i]->[($c / $self->{div}->[$i]) %
+ $self->{mod}->[$i]];
[download]

Woops