From: Joel VanderWerf <vjoel@...>
Date: 2004-11-05T08:21:39+09:00
Subject: Re: How to enumerate nested classes

Tim Hunter wrote:
> I have a class nested in a module:
> 
> module Foo
>    class Bar
>    ... buncha stuff here
>    end
> end
> 
> Within Foo::Bar there are many nested classes, not necessarily descended
> from Bar, simply contained within its namespace.
> 
> I would like to write a test that ensures that each class contained within
> Foo::Bar has a method named deep_copy() somewhere in its inheritence
> hierarchy. I'd like to write the test without explicitly listing all the
> nested classes. That is, if I add another class to Foo::Bar, then the test
> automatically checks it as well.
> 
> I thought I could do this via ObjectSpace.each_object(Foo::Bar) but that
> doesn't work. I also tried getting a list of Foo::Bar's constants and going
> from there but I got nowhere.
> 
> Any ideas?

You were on the right track:

module Foo
   class D; end
   class Bar
     class C1; end
     class C2; end
     K = 3
   end
end

p Foo::Bar.constants.map{|k|Foo::Bar.const_get(k)}.grep(Class)