From: Zev Blut <rubyzbibd@...>
Date: 2006-08-08T22:12:38+09:00
Subject: Re: Automatic instantiation of subclasses

On Tue, 08 Aug 2006 18:32:24 +0900, Mauricio Fernandez <mfp@acm.org> wrote:

> On Tue, Aug 08, 2006 at 06:19:12PM +0900, Kilivor Kante wrote:

>> So I want to know the names of A subclasses: A1 and A2. Then instantiate
>> via reflection. Is it possible?
>
> class A
>   class << self; attr_reader :subclasses end
>   def self.inherited(x); (@subclasses ||= []) << x end
> end


I am sure Mauricio knows this, but just in case others don't.  If you
use this particular solution a lot you might also want to call super,
because your class might inherit from another class that also wants to
use the inherited method. A simple change to fix this is:

def self.inherited(x); (@subclasses ||= []) << x; super; end

Cheers,
Zev