From: Rick DeNatale <rick.denatale@...>
Date: 2010-12-06T07:49:40+09:00
Subject: Re: Singleton class, metaclass, eigenclass: what do they mean?

On Sun, Dec 5, 2010 at 4:24 PM, Peter Vandenabeele
<peter@vandenabeele.com> wrote:
> On Sun, Dec 5, 2010 at 4:54 PM, Rick DeNatale <rick.denatale@gmail.com> wrote:
>> There's a much simpler explanation IMHO.
> ...
> Thanks for the detailed explanation.
>
>> The 'things' pointed to by klass pointers are either:
>
> Could this be a typo where you intended to say 'super' pointers?

I think I should have said klass or superclass pointers.
>
>> 1) class objects (like Array, Hash, Object etc)  if they are marked by
>> a flag that they are 'virtual' then they are not returned by methods
>> like class, superclass, ancestors, etc.
>
> From my findings:
>
> * the ancestors and the class method always hide it (as you write above)
> * the 'superclass' method _does_ return the first singleton classes
> pointed to by 'super'
>
> <code>
> $ irb
> ruby-1.9.2-head > class A < Object; end
>  => nil
> ruby-1.9.2-head > A.singleton_class
>  => #<Class:A>
> ruby-1.9.2-head > A.singleton_class.superclass
>  => #<Class:Object>
> </code>
>

That's a diference between Ruby 1.9 and 1.8  in 1.8.7

class B < A
end

B.superclass # => A
b_sing = class << B; self; end

b_sing.superclass # => #<Class:Class>

-- 
Rick DeNatale

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