use strict;
use warnings;

package Divisor;
use Carp;

sub new {
    my ($class, $divisor) = @_;
    croak "Not an integer: $divisor" if $divisor != int $divisor;

    my $instance = bless \$divisor => $class;
    $instance->_init($divisor);
}

sub _init {
    my ($instance, $divisor) = @_;
    
    $instance->set_divisibility_test(
        sub {
            my ($dividend) = @_;
            my $remainder = $dividend % $divisor;
            return ($remainder == 0);
        }
    );
    return $instance;
}

my %divisibility_test_for;

sub set_divisibility_test {
    my ($self, $code_ref) = @_;
    croak "Not a CODE ref: $code_ref" if ref $code_ref ne 'CODE';

    $divisibility_test_for{$self} = $code_ref;
}

sub divides {
    my ($self, $dividend) = @_;
    croak "Not an integer: $dividend" if $dividend != int $dividend;

    $divisibility_test_for{$self}($dividend);
}

'Divide et impera!';