From: Jamey Cribbs <jcribbs@...>
Date: 2006-03-05T11:55:07+09:00
Subject: Re: Kirbybase Hacks NilClass

Jamey Cribbs wrote:

> Dave Burt wrote:
>
>> You can subclass NilClass, but it has no allocator, so you'd have to 
>> define your own, and such an object still wouldn't be considered 
>> false in conditionals. There is only one nil, and only one false. So 
>> there is no point in subclassing NilClass.
>>
>>  
>>
> Yeah, I tried some of the same stuff Logan did in his email and 
> finally realized that NilClass won't let you subclass it.
>
> But, what if I did something like this:
>
> class KBNil
>    def method_missing(a,b)
>        nil
>    end
>
>    def nil?
>        true
>    end
> end
>
> Then, since, nil and false are the only things that don't evaluate to 
> true, if you do:
>
> k = KBNil.new
>
> puts 'True!' if k > 300 or 800 < 900    # True!
>
> puts 'False!' unless k > 300 or 800 < 900    # False!

Oops!  That should read:

puts 'False!' unless k > 300 and 800 < 900    False!

Jamey