#!/usr/bin/perl

use strict;
use warnings;


package Zvire;
use Moose;

# atributy
has 'jmeno' => (is => 'ro', required => 1);


package Zvire::Kocka;
use Moose;

extends 'Zvire';
# nic navic oproti tride Zvire


package Zvire::Pes;
use Moose;

extends 'Zvire';

has 'kocka' => (
	is => 'rw',
	isa => 'Zvire::Kocka',
	clearer => 'clear_kocka'
);

sub pronasleduj {
	my $self = shift;
	print $self->jmeno()
		, defined $self->kocka()
		  ? ' pronasleduje kocku/kocoura jmenem '
		    . $self->kocka()->jmeno()
		  : ' nepronasleduje nikoho'
		, ".\n";
}

package main;

my $tom = Zvire::Kocka->new(jmeno => 'Tom');
my $spike = Zvire::Pes->new(jmeno => 'Spike', kocka => $tom);

$spike->pronasleduj();
$spike->clear_kocka();
$spike->pronasleduj();