From: Aredridel <aredridel@...>
Date: 2004-07-08T07:43:27+09:00
Subject: Re: Class#=== has interesting results

> Why is that this is defined like that and not like this:
> 
>   Case Equality --- Returns true if anObject is an instance of mod, one of mod's
> descendents or _is mod_.

Because then it would match some instances of class Class, instances of
mod and instances of descendants of mod. That's three separate things,
two closely related and a third that's not.

It doesn't match descendants of mod -- it matches instances of
descendants of mod.

I can't think of any use-case where matching instances of Class in
addition to instances of Mod would be useful.

> I understand what it matches, that is not the purpose of my line of questions, I
> am asking why it doesn't also match itself, and for what reason you would want
> to match descendents of x but not x itself.  Does anyone have a logical reason
> why this is the case?

I think you confuse the kind_of? relation with the equals or "is"
relation. 

Class kind_of Class
Class kind_of Object
Object kind_of Object
Class is Class
mod is_a Class
instance kind_of mod
instance kind_of Object

but not 

instance kind_of Class
instance is_a Class

Ari