From: Bertram Scharpf <lists@...>
Date: 2009-07-04T23:34:10+09:00
Subject: Re: How to remove/delete/destroy class variable in Ruby 1.9?

Hi,

Am Samstag, 04. Jul 2009, 16:30:05 +0900 schrieb dzw!:
> Ok, code below shows better what I am talking about, I understand that
> @@var is acting like global variable.
> But how to get rid of it when is not needed anymore?
> 
> class A
>   @@var = 'var in A'
>   class <<self
>     def item      ; @@var       ; end
>     def item= var ; @@var = var ; end
>   end
> end
> class B
>   @@var = 'var in B'
>   class <<self
>     def item      ; @@var       ; end
>     def item= var ; @@var = var ; end
>   end
> end
> 
> 
> A.item #=>  "var in A"
> B.item #=>  "var in B"
> 
> A.item='test'
> A.item #=>  "test"
> B.item #=>  "var in B"
> 
> @@var ='ltl fkr'                #here is the funny part
> A.item         #=> "ltl fkr"
> B.item         #=> "ltl fkr"
> 
> A.item='test'                  #and here is getting even funnier
> A.item         #=> "test"
> B.item         #=> "test"    # i wish it to stay 'ltl fkr'

I cannot reproduce it here with Ruby 1.8.6. Are you using 1.9?

I guess A's and B's @@var gets superseded by Object's @@var.
Try to check these calls:

  Object.class_variables
  class Object ; remove_class_variable "@@var" ; end
  Object.instance_eval { remove_class_variable "@@var" }

  (Object.methods - Object.instance_methods).grep /var/
    #=> ["class_variables", "class_variable_defined?"]

  (Object.private_methods - Object.private_instance_methods).grep /var/
    #=> ["remove_class_variable", "class_variable_get", "class_variable_set"]

Bertram


-- 
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de