#! /usr/bin/env perl

use warnings;
use strict;

package BigObjs;
use Moose;
has 'little_objs' => ( is => 'rw', isa => 'HashRef', default => sub { {} } );

# our reader method
sub get_little_obj {
  my ($s, $id) = @_;

  return $s->little_objs->{$id};
}

# add new little objects to our collection
sub add_little_obj {
  my ($s, $little_obj) = @_;

  # create code ref to reader method in big object
  $little_obj->get_obj_by_id(sub{$s->get_little_obj(@_)});

  $s->little_objs->{$little_obj->id} = $little_obj;
}

package LittleObjs;
use Moose;

has 'id' => (is => 'rw');
has 'data' => (is => 'rw');
has 'get_obj_by_id' => (is => 'rw');

sub alter_another_little_object {
  my ($s, $id) = @_;
  my $other_little_object = $s->get_obj_by_id->($id);
  $other_little_object->do_stuff;
}

sub do_stuff {
  my $s = shift;
  print "I'm doing stuff to: " . $s->id . "\n";
}

no Moose;

my $big = BigObjs->new();
my $little1 = LittleObjs->new(id => 'little1', data => 'foo');
my $little2 = LittleObjs->new(id => 'little2', data => 'bar');

$big->add_little_obj($little1);
$big->add_little_obj($little2);

$little1->alter_another_little_object('little2');