From: "Mauricio Fernández" <batsman.geo@...>
Date: 2004-09-15T20:23:00+09:00
Subject: Re: Singleton method on object via define_method?

On Wed, Sep 15, 2004 at 05:09:52PM +0900, Robert Klemme wrote:
> >> o = Object.new
> => #<Object:0x10184d40>
> >> class << o; class << self; def to_s ; "foo" end end end
> => nil
> >> class << o; class << self;to_s end end
> => "foo"
> >> class << o; class << self; class << self; end end end
> => nil
> >> class << o; class << self; to_s end end
> => "#<Class:foo>"

It's using Module#to_s because the klass of the singleton class is
no longer itself... Module#to_s ends up calling 
 class << o; self.to_s end   
which you defined before.

> Hm, well ok.  But is there an equivalent without evil.rb, i.e. with
> "normal" Ruby code?  I know that you can access all kinds of internals if
> you write an extension, but AFAIK you can't know whether there is a
> singleton class or not. 

(I assume your last sentence if missing "... without an extension".)

The case above (singletons of singletons) is the only one I can think
of right now where you can always know if the singleton has been created
or not.

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