XML::Twig sort children on attribute (perl)

Hi,

I need to sort the children of the "Entries" element using the "a" attribute with XML::Twig but cannot find a method to do so. The structure is as follows:

<Entries>
    <datatag1 a="A1">
        <t>A</t>
    </datatag1>
    <datatag1 a="ABA1">
        <t>D</t>
    </datatag1>
    <datatag1 a="C1">
        <t>1</t>
    </datatag1>
    <datatag1 a="F1">
        <t>14</t>
    </datatag1>
    <datatag1 a="AB1">
        <t>1</t>
    </datatag1>
</Entries>

The desired order after sorting needs to be:

<Entries>
    <datatag1 a="A1">
        <t>A</t>
    </datatag1>
    <datatag1 a="C1">
        <t>1</t>
    </datatag1>
    <datatag1 a="F1">
        <t>14</t>
    </datatag1>
    <datatag1 a="AB1">
        <t>1</t>
    </datatag1>
    <datatag1 a="ABA1">
        <t>D</t>
    </datatag1>
</Entries>

However the alphabetical sorting using:

$root->sort_children_on_att('a');

does not give the desired results. This is expected as alphabetically AB follows A. Is there any other way to do the sorting with XML::Twig to get the desired result?

Any help much appreciated.

Twig's sorting methods don't accepts a custom sort method, but you can always use Perl's sort and cut/paste the nodes:

#!/usr/bin/perl
use warnings;
use strict;

use XML::Twig;

my $xml = '<Entries>...</Entries>';

sub sort_children {
    my $parent = $_;
    my @children = sort {
        length $a->att('a') <=> length $b->att('a')
        or $a->att('a') cmp $b->att('a')
    } $parent->cut_children;
    $_->paste(last_child => $parent) for @children;
}

my $twig = 'XML::Twig'->new(twig_handlers => { Entries => \&sort_children });
$twig->parse($xml);
$twig->print;