$ cat lib/A.pm 
package A;

use Moose;

has bar => (
    is  => 'rw',
    default => 'A-bar',
);

__PACKAGE__->meta->make_immutable;

##</code><code>##

$ cat lib/C.pm
package C;

use Moose;

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

    print "whos_who() is in package: ", __PACKAGE__, "\n";
    print "\$self is in package: ", ref($self), "\n";

    return;
}

__PACKAGE__->meta->make_immutable;

##</code><code>##

$ cat lib/D.pm
package D;

use Moose;

has 'bar' => (
    is  => 'rw',
    default => 'D-bar',
);

__PACKAGE__->meta->make_immutable;

##</code><code>##

$ cat lib/C1.pm
package C1;

use Moose;

extends 'C';
use A;
use D;

has a => ( is => 'ro', default => sub { A->new } );
has d => ( is => 'ro', default => sub { D->new } );

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

    print $self->a, "\n";
    print $self->a->bar, "\n";
    print $self->d, "\n";
    print $self->d->bar, "\n";
    $self->whos_who;

    return;
}

__PACKAGE__->meta->make_immutable;

##</code><code>##

$ cat ./acd.pl
#!/usr/bin/env perl

use strict;
use warnings;

use lib 'lib';

use C1;

my $c1 = C1::->new();

$c1->foo();

##</code><code>##

$ ./acd.pl
A=HASH(0x25db7c0)
A-bar
D=HASH(0x25db880)
D-bar
whos_who() is in package: C
$self is in package: C1