From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-07-12T07:06:09+09:00
Subject: Re: class_attr_accessor

On Tue, 12 Jul 2005, Jeffrey Moss wrote:

> I was playing around with class variables and class instance variables 
> because I wanted to implement a certain functionality, while not really 
> understanding the coexistence of the two, I found the reason the two exist is 
> quite clear, the class instance variables facilitate "subclass slots" (as I 
> know them from other languages) while the @@ syntax facilitates "class slots"
>
> I did a google search for "class_attr_accessor" and found that a number of 
> people have implemented this functionality in their own code.  I suggest it 
> be officially added to the ruby distribution.
>
> Here is an example:
>
> class Module
> private
> def class_attr_accessor(*attrs)
>   attrs.each {|attr|
>     module_eval(<<-EOS)
>       class << self
>         def #{attr}; @#{attr}; end
>         def #{attr}=(v); @#{attr} = v; end
>       end
>     EOS
>   }
> end
> end
>
> I really don't think a new notation, similar to @@, is necessary, I think 
> calling obj.class.accessor_name is very nice. In fact having both a 
> subclass_attr_accessor and a class_attr_accessor wouldn't hurt either. In 
> that case, class_attr_accessor would just be a way to make @@vars public.
>
> -Jeff Moss

check out

   http://raa.ruby-lang.org/project/traits/

inheritence is quite tricky with the impl of class_attr_accessor above.

cheers.

-a
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