use strict;
use warnings;

{
  package parent 0.000001;
  use Moose;

  has 'changing_data' => (is => 'rw',  default => '');

  sub set_data {
    my $s = shift;
    $s->changing_data('foo foo foo');
  }

  sub create_child {
    my $s = shift;
    my $data = shift;
    return child->new(changing_data => $data);
  }
}

{
  package child 0.00001;
  use Moose;
  extends 'parent';
}

my $p = parent->new();
$p->set_data;

my $child = $p->create_child(sub{$p->changing_data()});
print $child->changing_data->(); 
$p->changing_data('bar bar bar');
print "\n";
print $child->changing_data->();