my $instanceC = CLASS_C->new();
$instanceC->method_from_class_A();

##</code><code>##

package CLASS_C;
use CLASS_B;
@ISA = ('CLASS_B');
use strict;

sub new {
  my $proto = shift;
  my $class = ref($proto) || $proto;
  my $self = {};
  $self->{attribut} = 1;
  $self = $class->SUPER::new(self => $self);
  return $self;
}
1;

##</code><code>##

package CLASS_B;
use CLASS_A;
@ISA = ('CLASS_A');
use strict;

sub new {
  my $proto = shift;
  my (%params) = @_;
  my $class = ref($proto) || $proto;
  my $self = $class->SUPER::new();
  foreach my $attr (keys %{$params{'self'}}) {
    $self->{$attr} = $params{'self'}->{$attr};
  }
  return $self;
}
1;

##</code><code>##

package CLASS_A;
use strict;

sub new {
  my $proto = shift;
  my $class = ref($proto) || $proto;
  my $self = {};
  bless($self,$class);
  return $self;
}
1;