#!/usr/bin/perl
use strict;
use warnings;
use Sort::Topological qw/toposort/;
use Class::Struct Item => {
    id => '$',
    deps => '@',
};

my @items;
push @items, Item->new(id =>  $_) for 1..4;
# Make $items[1] a rank 'deeper', so it should sort last
$items[3]->deps([$items[1]]);

map { print "id: ", $_->id, "\n" } @items;
# 1, 2, 3, 4
@items = toposort(sub { my $i = shift; @{$i->deps}; }, \@items);
map { print "id: ", $_->id, "\n" } @items;
# 1, 3, 4, 2