package C::C1; # That's the perlish name for the module
use File::FindLib 'lib';

use A;
use B;
use C;
use D;

sub new {
   return bless({
        _a   => A->new->bar,  # I don't understand bar here
        _b   => B->new->bar1, # nor bar1 here
        _c   => C->new(),
        _d   => D->new(),
    }, shift);
}

# now for any method of A:
sub a_method_1 {
   my $self = shift;
   $self->_a->a_method 1(@_);
}
# etc

# And for any method of B:
sub b_method_1 {
   my $self = shift;
   $self->_a->b_method 1(@_);
}
# etc
# Repeat for C and D, ad libidum.

##</code><code>##

sub new_d {
    my $self = shift;
    if (@_) {
        $self->{_d} = D->new(@_);
    }
    return $self->{_d};
}

##</code><code>##

use C::C1;
my $c1 = C::C1->new;
$c1->a_method_1();   # will execute A::a_method_1
$c1->b_method_1();   # will execute B::b_method_1
$c1->new_d(@params)  # will execute $self->{_d} = D->new(@params)