From: ts <decoux@...>
Date: 2002-12-12T03:06:54+09:00
Subject: Re: all the pretty evals...

>>>>> "C" == Chris Pine <nemo@hellotree.com> writes:

C> I'm asking how this sort of singleton class differs from 'regular'
C> inheritance.

 a singleton class is a class which is associated with an unique object.

 For example

   class A
   end

   a = A.new
   b = A.new

 `a' and `b' has the same class

 When you write

   class << a
      def tt
         "tt"
      end
   end

 ruby create a singleton class which is associated only with `a', this will
 give methods specifics to `a'. In my example `a' respond to #tt but not
 `b' 

 If it was possible to create an instance from this singleton class, like

   klass = class << b; self; end
   c = klass.new

 This will means that `b' *AND* `c' will have the same singleton class, and
 this class can't be singleton (because it will be associated with 2
 objects).


Guy Decoux