If you have a variable number of fields as a hash with variable number of elements, you can iterate over the list, processing the fields one at a time.

use strict;
use warnings;
use Data::Dumper;

my %fields = (
    f1  => [ 1, 2 ],
    f2  => [ 3, 4, 5 ],
    f3  => [ 6, 7 ],
);

my @combinations = ( {} );

foreach my $field (keys %fields) {
    my @tmp;
    foreach my $value (@{$fields{$field}}) {
        foreach my $c (@combinations) {
            push(@tmp, { %$c, $field => $value } );
        }
    }
    @combinations = @tmp;
    print "Intermediate:\n" . Dumper(\@combinations);
}

print "Final:\n" . Dumper(\@combinations);

[download]

This program does not produce a hash of hashes, which you said you needed, but you may be able to adapt it to produce the data structure you need. It does demonstrate how a program can iterate over variable data similar to your field definitions.

You might find an introduction to programming helpful. For self study, there are pointers to many resources for learning Perl programming in Where and how to start learning Perl.

In reply to Re: Populating Hash of hashes by ig
in thread Populating Hash of hashes by zeni

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.