Rails/Ruby Mixin brings unwanted other class methods

Just hoping someone can explain this for me..

I have a Site class that imports a module:

Site

class Site < ActiveRecord::Base  
 include TrackableChanges  
 ...

In trackable_changes.rb

I have this code..

module TrackableChanges
  include ActiveSupport::Callbacks

  def self.included(base)
      # Initialize module.
      base.has_many :change_requests, :as => :model, :dependent => :destroy
      #Callbacks
      base.before_save :before_save_change_request
      base.after_save :after_save_change_request
      base.before_destroy :before_destroy_change_request

      Facility

  end 
...

The reference to Facility is really confusing me (I put a trivial reference in here..). Basically in Facility.rb I have this..

class Facility < ActiveRecord::Base
  acts_as_citier

acts_as_citier looks a bit like this:

module Citier
  def self.included(base) 
    # When a class includes a module the module’s self.included method will be invoked.
    base.send :extend, ClassMethods
  end
end

ActiveRecord::Base.send :include, Citier

Now.. Just by referencing Facility in my initial module it is going to the acts_as_citier gem and extending the ActiveRecord of my Site class. I want the acts_as_citier gem for my Facility but NOT for my Site.

Can anyone help stop this include trail bringing in this unwanted reference!?

EDIT

Seems like I can't reference the class Facility at all without it bringing in the开发者_运维问答 ActiveRecord class additions that is defined in the Facility via it's reference to the gem act_as_citier

cities does this...

ActiveRecord::Base.send :include, Citier

class Facility < ActiveRecord::Base
  #attr_accessible :name, :type, :facility_type_id, :accessibility_id, :tldc_id, :site_id, :tldc_approved  

  acts_as_citier if self.to_s == 'Facility' #Protects other classes from accidently getting the AR additions

Adding a condition to the include stops the acts_as_citier gem from extending any class that references 'Facility'.

I'm assuming the include on my Site class > runs through the module > which when it hits a reference to Facility class > runs through the Facility.rb > which runs through acts_as_citier and then hits the extend to active record line. It helped me remembering that every part of a .rb file is an executable.