From: Wayne Walker <wwalker@...>
Date: 2011-02-10T07:52:24+09:00
Subject: Trying to "inherit" class configuration and modify it

This gist has a bigger example of what I'm trying to do, but just
understanding how to make the following short example work, and/or why
it doesn't, will probably get me through the bigger problem.

testit.rb:

require 'pp'                                                                                                                                           
class A                                                                                                                                                
  @@a = [7]                                                                                                                                            
  def self.get_a                                                                                                                                       
    @@a                                                                                                                                                
  end                                                                                                                                                  
  def self.put_a                                                                                                                                       
    pp @@a                                                                                                                                             
  end                                                                                                                                                  
end                                                                                                                                                    
                                                                                                                                                       
class B < A                                                                                                                                            
  @@a = A.get_a.dup                                                                                                                                    
  @@a = [8]                                                                                                                                            
  def self.put_a                                                                                                                                       
    pp @@a                                                                                                                                             
  end                                                                                                                                                  
end                                                                                                                                                    
                                                                                                                                                       
A.put_a                                                                                                                                                
B.put_a                                                                                                                                                
A.put_a                                                                                                                                                

[wwalker@dogwood inherit_settings] $ ruby testit.rb
[8]
[8]
[8]

I would expect:
[7]
[8]
[7]

I don't see my error.  I think that maybe dup() doesn't work on a class
variable, or that maybe class variables are not really class variables,
but are rather hierarchy variables that can only exist in one place in
an class and it ancestry?

-- 

Wayne Walker
wwalker@solid-constructs.com
(512) 633-8076
Senior Consultant
Solid Constructs, LLC

> A: Because it messes up the order in which people normally read text.
> > Q: Why is top-posting such a bad thing?
> > > A: Top-posting.
> > > > Q: What is the most annoying thing in e-mail?