From: dblack@...
Date: 2007-06-27T07:38:05+09:00
Subject: Re: Error in ancestor?

Hi --

On Wed, 27 Jun 2007, Robert Dober wrote:

> On 6/26/07, dblack@wobblini.net <dblack@wobblini.net> wrote:
>
>> The thing is, there's one big difference that's not just a matter of
>> implementation: singleton classes of Class objects are the only ones
>> that can actually be called by more than one object (the class, plus
>> its descendants).
> I am definitely lost here, what do you mean by "can be called", their
> methods of course, ok so that is exactly what I meant, it is the
> "outside world" that makes the difference.

I meant the inheritance situation:

   class C
     def C.x
     end
   end

   class D < C
   end

   D.x   # D calling C's "singleton" method (which is therefore
         # not really singleton, because more than one object can
         # execute it).

> It is not the "fault" of the Singleton Class that it does not inherit
> from Module, could we imagine the following e.g.:
>
> s="a"
> t=class<<s
>  def hi; 42 end
>  self
> end
> c = Class.new{ include t }
>
> BTW I wanted just to be sure that this and some other tricks do not
> work and they don't :-(
> But Ruby threw a "Virtual Class" to me, actually did we discuss this
> name?, I quite like it.

I don't.

   (class << ""; self; end).is_a?(Object)  # => true

Nothing "virtual" about it :-)


David

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