From: Kyle Putnam <kyle@...>
Date: 2004-08-11T09:04:12+09:00
Subject: Re: Singleton class methods

On Tue, 2004-08-10 at 19:27, David A. Black wrote:
> Hi --
> 
> <<snip>>
> 
> It's the same as with any class: you can open its scope with the
> 'class' keyword (using "<< obj" to indicate the anonymous class you
> want), or you can capture it in a constant or variable and class_eval
> from there, and so on.  For example (using a non-Class object, just
> for a change of pace :-)
> 
>   x = "hi"
>   class << x
>     C = 1
>   end
> 
>   xclass = (class << x; self; end)
> 
>   puts xclass::C    # =>  1
> 
> This (class << x; self; end) thing is rather unwieldy, but there's an
> RCR pending for Kernel#singleton_class, which would then do for an
> object's singleton class what #class does for its class of origin.
> Here's that method, plus the above example rewritten to use it:
> 
>   module Kernel
>     def singleton_class; class << self; self; end; end
>   end
> 
>   x = "hi"
>   x.singleton_class::C = 1     # (or const_set if you prefer)
>   p x.singleton_class::C       # =>  1
> 
> 
> David

That makes it crystal clear! I was looking specifically for what you
demonstrated with xclass = (class << x; self; end).

Kernel#singleton_class seems like a great idea - had I seen that listed
from Object#methods it would've been obvious :)

Thanks!
    Kyle