From: Fernando Guillen <fguillen.mail@...>
Date: 2009-06-27T00:09:38+09:00
Subject: Trying to define a 'class' without using 'class' sentence

Hi people.. I was watching the Dave Thomas' talk on the ScotlandOnRails
2009 event about Ruby and the Object.

He say that a class does not exists on the Ruby land, a class is just an
instance of Class class.

So I was wondering, how could I define a 'class' without using the class
sentence .. I mean:

If I do this:

 <pre>
 class A
   def self.class_hello
     puts 'hello on class'
   end

   def instance_hello
     puts 'hello on instance'
   end
 end
 </pre>

I have a A class so I can start to instance instances of this class:

 <pre>
 a = A.new
 a.instance_hello
 A.class_hello
 </pre>

But as Dave says the A class is just constant instance of Class class,
so why not try to define a constant of an instance of Class class and
try to reproduce the same behavior:

 <pre>
 A = Class.new
 def A.class_hello
   puts 'hello on class'
 end

 a = A.new
 a.instance_hello # does not work
 A.class_hello
 </pre>

There it is, I could obtain the behavior of the class_hello but I
couldn't define the instance_hello with this approx.

So my questions are:

1) It is possible to obtain a total behavior of a Class constant without
the 'class' sentence?

2) What is the 'class' sentence?, because it is not a instance_method of
'main' that is an instance of Object, the Object#class method returns
the name of the class of the instance but not receive any kind of
arguments.

This doesn't work:

 <pre>
 self.class B
   def h
     puts "h"
   end
 end
 </pre>

This either:

 <pre>
 Object.class B
   def h
     puts "h"
   end
 end
 </pre>

So, as you can see I am trying to understand things that they should be
very simple, but for the moment my brain is not ready :)

f.
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