package Foo::Bar;

use Carp;
our @ISA = ();

1;

sub new {
  my ($class, %opt) = @_;
  my $self = {};
  bless ($self, $class);
  $self->init(%opt);
  return $self;
}

##</code><code>##

package Foo::Bar::Baz;

use strict;
use warnings;
use Carp;

our @ISA = qw( Foo::Bar );

1;

sub init {
  my $self = shift;
  my %opt = @_;
  
  # do the actual init for this specific class
}

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;
use Foo::Bar::Baz;

my $item = Foo::Bar::Baz->new();