From: Robert Klemme <bob.news@...>
Date: 2005-09-23T00:01:47+09:00
Subject: Re: Instantiating a subclass of NilClass.

Trans <transfire@gmail.com> wrote:
> I've subclasses NilClass, but don't know how to instantiate it. Any
> ideas?
>
>  class NullClass < NilClass
>    def inspect ; 'null' ; end
>    def method_missing(*args) ; self ; end
>  end
>
>  module Kernel
>    def null
>      NullClass.allocate #?
>    end
>  end
>
> T.

Hm...  I guess NilClass in Java lingo would be a final class, i.e., no 
inheritance allowed.

Btw, why do you want to do that?  I mean, you can create a class with 
nil-like behavior (apart from the boolean behavior I guess) without 
inheriting NilClass, can't you?

require 'singleton'

  class NullClass
    include Singleton

    def inspect ; 'null' ; end
    def nil?() true end
    def method_missing(*args) ; self ; end
  end

  module Kernel
    def null
      NullClass.instance
    end
  end

Kind regards

    robert