Simple OO problem ...

[Bee]

# test::load
package test::load;
require Exporter;
our @ISA = qw/Exporter/;
our @EXPORT = qw/new copy/;

sub copy 
{  my $self ;
     my $x = shift;
     my $y = $x -> {B};
     $y .= $y;
     $self -> {YY} = $y;
     bless $self;
     return $self;
 } 

sub new
{ my $self;
     $self -> {A} = shift;
     $self -> {B} = shift;
     bless $self;
     return $self; 
}
1;
__END__


# main
use test::load;

my $x = test::load -> new ( AAA => 111 );
my $y = $x ->copy ;
my $z = $y;

$y->{YY} = 100;
print $z -> {YY};
__END__

Question :
How can I make $z become another (blessed) thing ?
So when I modify something in $y , and not affecting $z ?

Thanks in advise,
Bee