Can I create Java-like interfaces in Perl?

Question

I understand that Perl's OO model is rather primitive; it is, in most respects, essentially a namespace hack.

Nevertheless, I wonder if it is possible to create something like an "interface?" My goal is to have a base class from which others are extended whose principal purpose is to make mandatory the implementation of certain methods (by name is fine, no signature necessary) by those subclasses. I don't really care if it's a "purely virtual" class (like an "interface" in Java) or a concrete class with actual implementational stubs for those methods in the superclass, but what I want is to make it deterministically necessary that the subclass implement certain methods of the superclass.

Is this possible? If so, how?

Answer 1

Here's an answer using Moose ...

package Comparable;
use Moose::Role;

requires 'eq';

package Person;

has size => (
    is   => 'ro',
    does => 'Comparable',
);

Now the size attribute must be an object which implements the Comparable "interface". In Moose-land, interfaces are roles, and roles can be more than just an interface definition.