Rails - Mar 2006 - Making AR attriibutes private

Hi,

Can anyone tell me the syntax to make AR attributes private so that they 
can only be set through an object''s constructor?

I want do something like this, where item_id and rated_by are private 
and set only through the constructor:


# Schema as of Mon Mar 06 21:22:59 BRT 2006 (schema version 15)
#
#  id                  :integer(11)   not null
#  item_id             :integer(11)   default(0), not null
#  rated_by            :integer(11)   default(0), not null
#  created_on          :datetime      not null
#  updated_on          :datetime      not null
#

class Wow < ActiveRecord::Base
  belongs_to :item
  validates_presence_of :item_id, :rated_by

  def initialize(item, user)
    super()
    self.item_id = item.id  
    self.rated_by = user.id
  end
 
end

How do I make item_id and rated_by private and still accessible 
internally by the constructor?

Thanks,

Tim Case
tim@karmacrash.com