package Foo;

sub new {
  my ($class) = @_;
  return bless [], $class;
}

sub val {
  my $self = shift;
  $self->[0] = $_[0] if @_;
  "Foo($self->[0])";
}

package Bar;

sub new {
  my ($class) = @_;
  return bless { val => 'nothing' }, $class;
}

sub val {
  my $self = shift;
  $self->{val} = $_[0] if @_;
  "Bar($self->{val})";
}

##</code><code>##

# Something to mixin
package Printer;

sub print {
  my $self = shift;
  my $val = $self->val;
  print "Value is $val\n";
}

##</code><code>##

package Foo2;
use vars '@ISA';
@ISA = qw(Foo Printer);

package Bar2;
use vars '@ISA';
@ISA = qw(Bar Printer);

##</code><code>##

package main;

my $x = new Foo2;
my $y = new Bar2;

$x->val(17);
$y->val('xyzzy');

$x->print;
$y->print;