From: Ara.T.Howard@...
Date: 2005-05-04T11:44:46+09:00
Subject: Re: un_metaclass

On Wed, 4 May 2005, Mark Hubbart wrote:

> On 5/3/05, Ara.T.Howard <Ara.T.Howard@noaa.gov> wrote:
>>
>> thoughts on how to do this
>>
>>    class C
>>      class << self
>>        p un_metaclass #=> C
>>      end
>>    end
>>
>> ??
>
> heh... I was ahead of you on that one :) in the "inside_metaclass?"
> thread, my solution returned the instance for the "true" value:
>
> http://rubytalk.org/140390
>
> class Class
> def metaclass?
>   id = inspect[/\A\#<Class:\#<.+?\:0x(.+?)>>\Z/, 1]
>   ObjectSpace._id2ref(id.to_i(16)/2) if id
> end
> end
>
> Note that this code is very fragile; it will not work on 1.6.x, and
> isn't guaranteed to work in the future. It extracts the object_id of
> the instance from the metaclass' inspect string.

it doesn't seem to work for me:

   jib:~/eg/ruby > cat a.rb

   class Module
     def instance_class
       m = %r/^(?:#<Class:)+(.*?)(>+)$/io.match inspect
       if m
         klass_name, brackets = m[1], m[2]
         n = brackets.size - 1
         klass = const_get klass_name
         n.times{ klass = class << klass; self; end }
         klass
       else
         superclass
       end
     end
     def metaclass?
       id = inspect[%r/\A\#<Class:\#<.+?\:0x(.+?)>>\Z/, 1]
       ObjectSpace._id2ref(id.to_i(16)/2) if id
     end
     def both
       [ instance_class, metaclass? ]
     end
   end

   class C
     p both
     class << self
       p both
       class << self
         p both
         class << self
           p both
         end
       end
     end
   end

   class K < C
     p both
     class << self
       p both
       class << self
         p both
         class << self
           p both
         end
       end
     end
   end

   jib:~/eg/ruby > ruby a.rb
   [Object, nil]
   [C, nil]
   [#<Class:C>, nil]
   [#<Class:#<Class:C>>, nil]
   [C, nil]
   [K, nil]
   [#<Class:K>, nil]
   [#<Class:#<Class:K>>, nil]


did i do something wrong?

-a
-- 
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