From: "David A. Black" <dblack@...>
Date: 2004-02-16T11:29:53+09:00
Subject: Re: inheritence of class vars

Hi --

On Mon, 16 Feb 2004, Florian G. Pflug wrote:

> On Sat, Feb 14, 2004 at 10:44:04AM +0900, David A. Black wrote:
> > Class variables, at least through 1.8.x, are essentially per-hierarchy
> > and not per-Class-object.  For 1.9/2.0, though, Matz has presented the
> > following new rules:
> > 
> >   * class variables will be local to the class/module
> >   * if you need to access class variables from outside,
> >     define accessors
> 
> Might be me being stupid.. but if these new rules are in place, what will
> the difference between class variables and instance variables (of class
> objects) be?
> 
> The only thing coming to my mind, is that class variables are easily
> accessed from instance methods, while you need to do
> "self.class.class_eval{@my_class_instance_var}" for class-object instance
> variables.

I think that's the main difference, at least in terms of usage.
That's what makes me have doubts about it; I'm not sure what purpose
class variables will serve except to save some typing.  

> BTW: Just for the sake of being curious... is it possible to define
> class-variables of the class Class?

Sure, you can do this:

  class Class
    @@x = 1
  end


David

-- 
David A. Black
dblack@wobblini.net