From: "David A. Black" <dblack@...>
Date: 2007-10-24T07:05:52+09:00
Subject: Re: terminology: class methods versus kernel methods

Hi --

On Wed, 24 Oct 2007, Thufir wrote:

> On Oct 23, 2:45 pm, "Rick DeNatale" <rick.denat...@gmail.com> wrote:
> [...]
>> print is an instance method of the Kernel module.
>>
>> The Object class includes Kernel, so the instance methods of Kernel
>> are effectively instance methods of every object, at least in Ruby
>> 1.8.
> [...]
>
> Kernel is a class, sub-class, of Object?

Kernel is a module. Object mixes it in -- essentially:

   class Object
     include Kernel
   end

so that every instance of Object, or a subclass of Object, gets access
to the instance methods defined in Kernel.

Of course, the module Kernel is, itself, an Object :-) You'll find
that if you look closely at the top of the object tree in Ruby, there
are some circularities:

   - Kernel is a Module
   - Module is a Class
   - Class is a subclass of Module
   - Object is a Class
   - Class is an Object

etc.  Don't worry about it, though.  The reason there's circularity at
the top of the object tree is so that the rest of the object tree --
i.e., everything you really need to do -- makes sense.


David

-- 
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