http://www.perlmonks.org?node_id=514941

Inspired by the discussion of How to use Inheritance with Inside-Out Classes and Hash Based Classes, I have added the capability for Object::InsideOut objects to inherit from non-Object::InsideOut classes. (I refer to this as foreign inheritance in the POD.) Thus, using Object::InsideOut, you can now sub-class other Perl classes, and have access to their methods from your own inside-out objects.

Here's a quick-and-dirty sample that illustrates foreign inheritance using Object::InsideOut v1.18:

use strict; use warnings; # Borg is a foreign hash-based class package Borg; { # A regular hash-based constructor sub new { return (bless({}, shift)); } # A 'get' accessor sub get_borg { my ($self, $data) = @_; return ($self->{$data}); } # A 'put' accessor sub set_borg { my ($self, $key, $value) = @_; $self->{$key} = $value; } # A class method sub assimilate { return ('Resistance is futile'); } } # Foo is an Object::InsideOut class that inherits from class Borg package Foo; { use Object::InsideOut qw(Borg); # A data field with standard 'get_/set_' accessors my @foo :Field('Standard'=>'foo'); # Our class's 'contructor' sub init :Init { my ($self, $args) = @_; # Create a Borg object and inherit from it my $borg = Borg->new(); $self->inherit($borg); } # A class method sub comment { return ('I have no comment to make at this time'); } } package main; # Inheritance works on class m +ethods print(Foo->comment(), "\n"); # Call a 'native' class meth +od print(Foo->assimilate(), "\n"); # Call a 'foreign' class met +hod my $obj = Foo->new(); # Create our object $obj->set_foo('I like foo'); # Set data inside our object print($obj->get_foo(), "\n"); # Get data from our object $obj->set_borg('ID' => 'I am 5-of-7'); # Set data inside inherited ob +ject print($obj->get_borg('ID'), "\n"); # Get data from inherited obje +ct
Other points of interest:
  • Muliple inheritance is supported with any mix of Object::InsideOut and foreign classes.
  • The encapsulation of the inherited objects is strong, meaning that only the class where the inheritance takes place has direct access to the inherited object.
  • Disinheritance is supported to remove the association with an inherited object.
Any comments or suggestions from my fellow monks would be greatly appreciated. Enjoy.

Remember: There's always one more bug.