Container      = SharedHouse
Element        = Person
->do_something = ->pay_rent
[download]

this used to work as long as one Person could only live in ONE house at a time.

my $cont = SharedHouse->new('Prag');
my $elem = Person->new('Egon');
$cont->add_elem($elem);

# method chaining
$cont->get_elem('Egon')->pay_rent();
[download]

Now the requirement changed to manage multiple houses in the same program with overlapping sets of inhabitants.

my best guess is that get_elem should now return an object of a new class Inhabitant pointing to one SharedHouse and one Person

• handles methods involving the Container directly
• delegates other methods to an object Person

$elem1 = $cont1->get_elem('Egon');
$elem2 = $cont2->get_elem('Egon');
[download]

but both are internally pointing to the same Person 'Egon'

$elem1->{person} == $elem2->{person}

such that

$elem1->pay_rent() pays the rent for the SharedHouse object in $cont1

but

$elem1->comb_hair() delegates to $elem1->{person}->comb_hair()

I hope it's clearer now. :)

(the real model is even more complicated, since the container is actually a matrix of two types of elements and values in the cell. Think of objects of type Room like $kitchen, and $Egon->owns("Kitchen", "Table"); )