From: Jim Freeze <jim@...>
Date: 2003-05-09T21:14:58+09:00
Subject: Re: Can a global be a constant?

On Friday,  9 May 2003 at 16:18:43 +0900, Mauricio Fern�ndez wrote:
> On Fri, May 09, 2003 at 01:13:51PM +0900, Jim Freeze wrote:
> > So, fundamentally, is the code in both class C and D below 
> > doing the same thing?
> > 
> > class C 
> >   class << self
> >     def set(x); @x = x; end  
> >     def get; puts @x; end
> >   end
> > end
> > 
> > class D
> >   def self.set; @x = x; end
> >   def self.get; puts @x; end
> > end
> 
> > If these class methods have instance variables for the 
> > singleton object, are class methods not just really
> > instance methods of the singleton object?
> 
> I don't think "singleton object" is standard terminology here.
> Regardless of the use of class instance variables, class methods are in
> fact singleton methods of the object that represents the class (i.e.,
> that of type Class). You can also view them as instance methods of the
> associated *singleton class*. 
> 

Hmm, associated singleton class seems weird to me.
Why does an object (in this case a class object) 
have an associated singleton class? Don't objects 
just have single methods added to them?

> batsman@tux-chan:/tmp$ expand -t2 ad.rb
> 
> class Foo
>   puts "Foo.id:  #{id}"
>   class << self
>     def foo
>     end
> 
>     puts "Foo'.id: #{id}"
>     puts "Foo' instance methods: " + instance_methods.inspect
>   end
>   puts "Foo singleton methods:" + singleton_methods.inspect
> end
> 
> batsman@tux-chan:/tmp$ ruby ad.rb
> Foo.id:  537725700
> Foo'.id: 537725690

I'm having troubles understanding the Foo and Foo' objects.
Can you explain more?

-- 
Jim Freeze
----------
Misery no longer loves company.  Nowadays it insists on it.
		-- Russell Baker