From: Jeremy Hinegardner <jeremy@...>
Date: 2008-05-23T03:22:40+09:00
Subject: Re: Prevent ruby constant variables from changing?

On Thu, May 22, 2008 at 04:49:32PM +0900, Pe??a, Botp wrote:
> From: George Wang [mailto:stdcells@yahoo.com] 
> 
> i too had this problem, and the closest i can get is to wrap the constants in
> a module and then freeze the module.

Interesting new knowledge for me when I test this out.  I didn't know that what
is returned from the end of a class ... end and module .. end block is NilClass.

  % cat x.rb
  module C
    X = 42
  end.freeze

  puts "C::X => #{C::X}"
  C::X = 99

  puts "C::X => #{C::X}"
  C.freeze
  C::X = 42

  puts "C::X => #{C::X}"

  % ruby x.rb
  C::X => 42
  x.rb:6: warning: already initialized constant X
  C::X => 99
  x.rb:10: can't modify frozen module (TypeError)

Hmm... lets look at what is returned by the end of a module and a class

 % cat c.rb
 c = class C; end
 puts c.inspect

 m = module M; end
 puts m.inspect

 % ruby c.rb
 nil
 nil

You learn something new every day.

enjoy,

-jeremy    



-- 
========================================================================
 Jeremy Hinegardner                              jeremy@hinegardner.org