package Parent;
use Moose;

has 'knibbel' => (
	is => 'rw', 
	isa => 'HashRef[Maybe[Value]]',
	lazy_build => 1,
);
has 'knabbel' => (
	is => 'rw', 
	isa => 'ArrayRef[Maybe[Value]]',
	lazy_build => 1,
);

sub BUILD {
	my $self = shift;
	my $meta = $self->meta;
	print("BUILD called for " . __PACKAGE__ . "\n");
	no strict;
	foreach my $attribute ($meta->get_attribute_list) {
		print("Creating builder for attribute [$attribute]\n");
		*{__PACKAGE__ . '::_build_' . $attribute} = sub {
			my $self = shift;
			my $meta = $self->meta;
			my $fropsel = $meta->get_attribute($attribute);
			if ($fropsel->type_constraint->name =~ /^ArrayRef/) { return []; }
			if ($fropsel->type_constraint->name =~ /^HashRef/) { return {}; }
		};
	}
	use strict;
}
1;

##</code><code>##

package Child;
use Moose;
extends 'Parent';

has 'knuisje' => (
	is => 'rw', 
	isa => 'Str',
	lazy_build => 1,
);

sub BUILD {
	my $self = shift;
	my $meta = $self->meta;
	print("BUILD called for " . __PACKAGE__ . "\n");
	no strict;
	foreach my $attribute ($meta->get_attribute_list) {
		print("Creating builder for attribute [$attribute]\n");
		*{__PACKAGE__ . '::_build_' . $attribute} = sub {
			my $self = shift;
			my $meta = $self->meta;
			my $fropsel = $meta->get_attribute($attribute);
			if ($fropsel->type_constraint->name =~ /^Str/) { return ""; }
		};
	}
	use strict;
}
1;

##</code><code>##

#!/usr/bin/perl -w
use strict;

use Parent;
use Child;

my $child = Child->new();

##</code><code>##

$ ./testchild.pl
BUILD called for Parent
Creating builder for attribute [knuisje]
BUILD called for Child
Creating builder for attribute [knuisje]