Rails - May 2011 - self.included like a constructor method that gets called when a module is included in a class?

Hey all,

Let''s say you have a controller class and you include a module:

class ApplicationController < ActionController::Base
  include AuthenticationSystem

  def default_page
    case
      when cu.group_is?(:a) then a_path
      when cu.group_is?(:b) then b_path
      when cu.group_is?(:c) then c_path
    end
  end
end

Notice how this method makes a call to method cu. Now in order for cu to
exist, that means the module methods must be copied into
ApplicationController before any of its methods are called by
subclasses:

class DashboardController < ApplicationController
  def root
    redirect_to default_page
  end
end

If the module methods were not included prior to default_page being
called in ApplicationController, since default_page calls method cu
defined in the module AuthenticationSystem, it would throw error.

That part is clear. But what is unclear is what''s the whole purpose of
this:

module AuthenticationSystem
  def self.included(base)
    base.send :helper_method, :current_user
  end
end

If, for example, current_user setter/getter are already declared in
module:


  def current_user
    @current_user = User.find_by_id(session[:user_id])
  end

  alias :cu :current_user

  def current_user=(new_user)
    session[:user_id] = new_user ? new_user.id : nil
    @current_user = new_user
  end

and thus will be copied into the ApplicationController class, then
what''s the point of sending it to the class using base.send when it
will
already be copied into the class?

Or is base.send like a contructor method that gets executed before
anything else in the module and therefore when its included in a class,
it acts as consutrcotr of class and gets called prior to any methods of
the class being called?

Thanks for response.

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On May 9, 8:03 pm, John Merlino
<li...-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org>
wrote:
> Hey all,
>
> Let''s say you have a controller class and you include a module:
>
> module AuthenticationSystem
>   def self.included(base)
>     base.send :helper_method, :current_user
>   end
> end
>
The point of this is to call helper_method :current_user. You can look
up what helper_method does in the rails docs.

Fred
> If, for example, current_user setter/getter are already declared in
> module:
>
>   def current_user
>     @current_user = User.find_by_id(session[:user_id])
>   end
>
>   alias :cu :current_user
>
>   def current_user=(new_user)
>     session[:user_id] = new_user ? new_user.id : nil
>     @current_user = new_user
>   end
>
> and thus will be copied into the ApplicationController class, then
> what''s the point of sending it to the class using base.send when
it will
> already be copied into the class?
>
> Or is base.send like a contructor method that gets executed before
> anything else in the module and therefore when its included in a class,
> it acts as consutrcotr of class and gets called prior to any methods of
> the class being called?
>
> Thanks for response.
>
> --
> Posted viahttp://www.ruby-forum.com/.
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> The point of this is to call helper_method :current_user. You can look
> up what helper_method does in the rails docs.
>
> Fred
ok so basically this allows you to use current_user in your views.

thanks for response

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