package Animal;

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

1;

-------------------------------------------------------------------

package Cat;
use strict;

use Animal;
our @ISA = qw(Animal);

sub speak {
  print "meow...\n";
}

1;

-------------------------------------------------------------------

package Dog;
use strict;

use Animal;
our @ISA = qw(Animal);

sub speak {
  print "woof...\n";
}

1;

---------------------------------------------------------

#!/usr/bin/perl

use strict;
use warnings;

use Dog;
use Cat;

my $dog = Dog->new();
my $cat = Cat->new();

$dog->speak;
$cat->speak;