From: Logan Capaldo <logancapaldo@...>
Date: 2006-05-04T14:28:29+09:00
Subject: Re: Ruby idiom for attributes / properties


On May 4, 2006, at 1:07 AM, John Lam wrote:

> Excellent!
>
> Now the bigger question is - any chance this could become part of the
> standard distribution? I could add another special case in my  
> bridge to
> marshal traits auto-magically as well, but it would rock if this  
> mechanism
> could be something that I could grab a hold of when reflecting  
> against Ruby
> objects at the marshaling boundary.
>
> -John
> http://www.iunknown.com

You could do

class Module
  alias old_attr_reader attr_reader
  alias old_attr_writer attr_writer
  alias old_attr_accessor attr_accessor

  def attr_reader(*args)
      self.attributes |= args
      old_attr_reader(*args)
  end

  def attr_writer(*args)
      self.attributes |= args
      old_attr_writer(*args)
  end

  def attr_accessor(*args)
      self.attributes |= args
      old_attr_accessor(*args)
  end

  def attributes
      @attribs ||= []
  end

  def attributes=(new_attribs)
      @attribs = new_attribs
  end
end

class A
   attr_accessor :a
end

p A.attributes

Note that you'd have to make sure this was required before anything  
else, and it only works for attributes declared with the attr_*  
family of methods