From: "David A. Black" <dblack@...>
Date: 2004-03-09T01:53:52+09:00
Subject: Re: proposal:  class<<obj to invoke extend_object

Hi --

On Tue, 9 Mar 2004, Carlos wrote:

> [Simon Strandgaard <neoneye@adslhome.dk>, 2004-03-08 16.19 CET]
> > On Tue, 09 Mar 2004 00:02:13 +0900, Carlos wrote:
> > [snip] 
> > > Maybe you should ask for a method #singleton for singleton classes,
> > > that returns the object... ;)
> > 
> > I tried poking around with 'singleton'.. but no luck.
> > Please give me some more hints.
> 
> No... it doesn't exist (as I know), but if it existed, you could
> do what you are trying to do with
> 
> class << obj
>   def init
>     ...
>   end
> 
>   singleton.init
> end
> 
> This is why I said that maybe you should ask for it (to Matz). Sorry
> for false expectations...

Here's a brute-force but perhaps useable implementation:

  class Class
    def single_instance
      ObjectSpace.each_object do |obj|
	c = (class << obj; self; end)
	return obj if c == self
      end
    end
  end

  p (class << "hello"; self; end).single_instance   # "hello"


David

-- 
David A. Black
dblack@wobblini.net