#!/usr/local/bin/perl
use strict;
use warnings;
{
    package Dummy;
    sub new { bless $_[1], $_[0] }
    sub DESTROY { warn "($_[0])" }
}
{
    my $fact;
    $fact = sub{ $_[0] <= 1 ? $_[0] : $_[0] * $fact->($_[0] - 1) };
    bless $fact, 'Dummy';
    print $fact->(10), "\n";
}
warn "Goodbye, world!";