From: "David A. Black" <dblack@...>
Date: 2003-11-29T12:57:37+09:00
Subject: Re: Class-level readers and writers

Hi --

On Sat, 29 Nov 2003, Carl Youngblood wrote:

> I've been working with the class attribute shortcuts that Hal introduced 
> in THE RUBY WAY:
> 
> class Class
> 	def cattr_reader(*syms)
> 		syms.each do |sym|
> 			class_eval <<-EOS
> 				if !defined? @@#{sym.id2name}
> 					@@#{sym.id2name} = nil
> 				end
> 				def self.~{sym.id2name}
                                         ^  typo here
> I'm having a problem, however, in that classes that are inherited from 
> the ones in which I declare these attrs don't seem to have them anymore. 
>   Does anyone know how I can make my declared class attributes get 
> inherited?

I ran your code (except for the typo :-) with this added:

  class A; cattr_accessor(:x); end
  class B < A; end
  B.x = 1
  puts B.x

and it printed 1, so I think the error must be somewhere else.  

(Just as a footnote, you can also use "normal" accessor shortcuts at
the class object level:

  class A
    class << self
      attr_accessor :x
    end
  end

  A.x = 1   # and so on

which is implemented with instance variables rather than class
variables, if for any reason that suits your purposes better.)


David

-- 
David A. Black
dblack@wobblini.net