http://www.codeproject.com/perl/camel_poop.asp

##</code><code>##

#class Person
package Person;
use strict;
use Address;    #Person class will contain an Address

#constructor
sub new {
    my ($class) = @_;
    my $self = {
        _firstName => undef,
        _lastName  => undef,
        _ssn       => undef,
        _address   => undef
    };
    bless $self, $class;
    return $self;
}

#accessor method for Person first name
sub firstName {
    my ( $self, $firstName ) = @_;
    $self->{_firstName} = $firstName if defined($firstName);
    return $self->{_firstName};
}

#accessor method for Person last name
sub lastName {
    my ( $self, $lastName ) = @_;
    $self->{_lastName} = $lastName if defined($lastName);
    return $self->{_lastName};
}

#accessor method for Person address
sub address {
    my ( $self, $address ) = @_;
    $self->{_address} = $address if defined($address);
    return $self->{_address};
}

#accessor method for Person social security number
sub ssn {
    my ( $self, $ssn ) = @_;
    $self->{_ssn} = $ssn if defined($ssn);
    return $self->{_ssn};
}

sub print {
    my ($self) = @_;

    #print Person info
    printf( "Name:%s %s\n\n", $self->firstName, $self->lastName );
}

1;

##</code><code>##

# class Employee
package Employee;
use Person;
use strict;
our @ISA = qw(Person);    # inherits from Person

#constructor
sub new {
    my ($class) = @_;

    #call the constructor of the parent class, Person.
    my $self = $class->SUPER::new();
    $self->{_id}   = undef;
    $self->{_title} = undef;
    bless $self, $class;
    return $self;
}

#accessor method for  id
sub id {
    my ( $self, $id ) = @_;
    $self->{_id} = $id if defined($id);
    return ( $self->{_id} );
}

#accessor method for  title
sub title {
    my ( $self, $title ) = @_;
    $self->{_title} = $title if defined($title);
    return ( $self->{_title} );
}

sub print {
    my ($self) = @_;

    # we will call the print method of the parent class
    $self->SUPER::print;
    $self->address->print;
}

1;

##</code><code>##

use strict;
use warnings;
use diagnostics;
use Employee;

#create Employee class instance
my $khurt =  eval { new Employee(); }  or die ($@);
 
#set object attributes
$khurt->firstName('Khurt');
$khurt->lastName('Williams');
$khurt->id(1001);
$khurt->title('Executive Director');

$khurt->address( new Address() );

$khurt->address->street('10 Anywhere Lane');
$khurt->address->city('Anytown');
$khurt->address->state('NJ');
$khurt->address->zip('12345');

#diplay Employee info
$khurt->print();

##</code><code>##

Can't locate Address.pm in @INC (@INC contains: /script/perl/test2/modules /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.7/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.6/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.5/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl/5.8.7 /usr/lib/perl5/site_perl/5.8.6 /usr/lib/perl5/site_perl/5.8.5 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.7/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.6/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.5/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl/5.8.7 /usr/lib/perl5/vendor_perl/5.8.6 /usr/lib/perl5/vendor_perl/5.8.5 /usr/lib/perl5/vendor_perl /usr/lib/perl5/5.8.8/i386-linux-thread-multi /usr/lib/perl5/5.8.8 .) at /script/perl/test2/modules/Person.pm line 4.
BEGIN failed--compilation aborted at /script/perl/test2/modules/Person.pm line 4.
Compilation failed in require at /script/perl/test2/modules/Employee.pm line 3.
BEGIN failed--compilation aborted at /script/perl/test2/modules/Employee.pm line 3.
Compilation failed in require at ./first.obj line 6.
BEGIN failed--compilation aborted at ./first.obj line 6 (#1)
    (F) You said to do (or require, or use) a file that couldn't be
    found. Perl looks for the file in all the locations mentioned in @INC,
    unless the file name included the full path to the file.  Perhaps you
    need to set the PERL5LIB or PERL5OPT environment variable to say where
    the extra library is, or maybe the script needs to add the library name
    to @INC.  Or maybe you just misspelled the name of the file.  See
    perlfunc/require and lib.
    
Uncaught exception from user code:
        Can't locate Address.pm in @INC (@INC contains: /script/perl/test2/modules /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.7/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.6/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.5/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl/5.8.7 /usr/lib/perl5/site_perl/5.8.6 /usr/lib/perl5/site_perl/5.8.5 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.7/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.6/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.5/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl/5.8.7 /usr/lib/perl5/vendor_perl/5.8.6 /usr/lib/perl5/vendor_perl/5.8.5 /usr/lib/perl5/vendor_perl /usr/lib/perl5/5.8.8/i386-linux-thread-multi /usr/lib/perl5/5.8.8 .) at /script/perl/test2/modules/Person.pm line 4.
BEGIN failed--compilation aborted at /script/perl/test2/modules/Person.pm line 4.
Compilation failed in require at /script/perl/test2/modules/Employee.pm line 3.
BEGIN failed--compilation aborted at /script/perl/test2/modules/Employee.pm line 3.
Compilation failed in require at ./first.obj line 6.
BEGIN failed--compilation aborted at ./first.obj line 6.
 at ./first.obj line 6