Careful, B is an actual core module.

Yes, I am am aware of that. Am just using A, B, C... as placeholders (too many Algebra lessons for my daughter).

It may help decide if you reflect on whether A is-a B and A is-a C. Compare that to your answers to the same question with has-a substituted.

Nice. Put that way, A has-a B and has-a C. Thanks for your aggregation code. I will work with that tact.

That said, could I do something like...

package A;
use B;
use C;
use strict;

sub new {
    my ($class) = @_;
    bless {}, $class;
}

sub make_B {
    my ($self) = shift;
    return new B(@_);
}

sub make_C {
    my ($self) = shift;
    return new C(@_);
}

### and then, in my script...
use A;
my $a = A->new();
# $a has all the methods of A

my $b = $a->make_B('a', 'b');
# now $b has all the methods of B

my $c = $c->make_C('c', 'd');
# and $c has all the methods of C
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