Moose is an excellent suggestion.

#!/usr/bin/perl

use strict;
use warnings;

my $red = Apple->new( color => 'green'  );
my $yel = Apple->new( color => 'yellow' );

$red->color( 'red' ); # It got ripe.

my $foo = Orange->new();
my $baz = Orange->new( apple => $red ); 

for my $obj ( $red, $yel, $foo, $baz ) {
    print 'served: ', $obj->serve, "\n";
}

print "\n fruit stand: \n",
    map $_->dump, $red, $yel, $foo, $baz;


BEGIN {
    package Apple;

    use Moose;
    use namespace::autoclean;

    has 'color' => (
        is => 'rw',
        isa => 'Str',
    );

    sub serve {
        return 'sliced';
    }

    __PACKAGE__->meta->make_immutable;
    1;
}

BEGIN {
    package Orange;

    use Moose;
    use namespace::autoclean;

    has 'apple' => (
        is => 'ro',
        isa => 'Apple',
        predicate => 'has_apple',
    );

    has 'shape' => (
        is => 'ro',
        isa => 'Str',
    );

    sub serve {
        my $self = shift;
        return $self->has_apple 
             ? $self->apple->serve() 
             : 'squeezed';
    }

    __PACKAGE__->meta->make_immutable;
    1;
}
[download]

I like to put all my extra packages in BEGIN blocks since it makes them as much work as much like they were used as possible. I also put the trailing true value in, so that I can grab them and dump them straight into a separate file if it should become desirable to break them out. This simple step has prevented me from having to rerun zillions of tests via make test and prove