From: Joel VanderWerf <vjoel@...>
Date: 2009-08-13T04:39:20+09:00
Subject: Re: Class#descendants?

Jason Lillywhite wrote:
> Ruby can do Class#ancestors but not Class#descendants.
> 
> I found this: http://termos.vemod.net/class-descendants
> 
> But it only works after you define a new inheritance. Is there a way to
> find descendants of a class that is already in place? For example:
> 
> Numeric.descendants
> => [Integer, Float, Complex]
> 
> Thank you.

irb(main):001:0> ObjectSpace.each_object(Class) {|cl| p cl if cl < Numeric}
Bignum
Float
Fixnum
Integer

But keep in mind: it's inefficient (so cache if you can), and it may not 
be standard across rubies (jruby may not have it IIRC). It's useful for 
interactive poking around though.

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407