From: dblack@...
Date: 2006-08-25T03:23:36+09:00
Subject: Re: Call functions of superclass

Hi --

On Fri, 25 Aug 2006, Nathan Smith wrote:

>> I think you're adding an extra level of reference or indirection or
>> something.  Look at this:
>>
>> irb(main):001:0> class C; object_id; end
>> => 1615634
>> irb(main):002:0> C.new.class.object_id
>> => 1615634
>> irb(main):003:0> C.new.class.superclass.object_id
>> => 1683084
>> irb(main):004:0> C.new.class.superclass
>> => Object
>> irb(main):005:0> Object.object_id
>> => 1683084
>> irb(main):006:0> class << C; object_id; end
>> => 1615554
>>
>> As you can see, the singleton class of C is not the same object as
>> either C or the class of C.
>>
>> ("Singleton class" is the most general term; the Pickaxe uses
>> "metaclass" to mean singleton class of a Class object.  I tend to just
>> use "singleton".)
>
> I concede your point -- I was using singleton as the object-specific
> class, while it is the opposite of that. Thanks for the clarification.
> Maybe now my arguments will make more sense!

It doesn't sound like I clarified it.... :-)  The singleton class *is*
the object-specific class.  Here's a common idiom that illustrates it:

   class Object
     def singleton_class
       class << self
         self
       end
     end
   end

It sounds like this came out backwards -- ?


David

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