#!/usr/bin/perl -w

use strict;

package TieLazy;

use Tie::Hash;
@TieLazy::ISA = qw( Tie::StdHash );

sub new {
	my $class = shift;
	my %data;
	tie %data, "TieLazy", @_;
	bless \%data, $class;
}

sub TIEHASH {
	my $self = shift;
	my %data = %{ +shift };
	bless \%data, $self;
}

sub FETCH {
	my $self = shift;
	my $item = shift;
	if (defined(my $data = ($self->{$item}))) {
		if (ref($data) eq 'CODE') {
			return $self->{$item} = $data->();
		} else {
			return $self->{$item};
		}
	}
}


##</code><code>##

sub do_two {
	print "Doing two!\n";
	return 2;
}

my $tl = TieLazy->new({one => 1, two => \&do_two});
print join("\t", @$tl{qw( one two two )} ), "\n";

$tl->{three} = 3;
print "$$tl{three}\n";

$tl->{four} = sub { print "Four!\n"; return 4; };

print "Four exists!\n" if (exists($tl->{four}));

print "$$tl{four}\n";
print "$$tl{four}\n";