class versus instance method - how?

I have a file call authentication.rb in rails root/lib directory which has the following method defined amongst others:

module Authentication   ...   def authorize_admin?     logged_in? && has_role?('admin')   end   ... end

This module is included into application.rb as follows:

class ApplicationController < ActionController::Base

  # Ryan's stripped down Authentication module from Restful_Authentication   include Authentication   # Tim Harper's RoleRequirement module from his plugin   include RoleRequirementSystem

end

I am also using Ryan Heath's excellent navigation_helper plugin which has a "current_tab" class method. You set the current_tab at the controller level as follows:

class UsersController < ApplicationController

  before_filter :login_required   current_tab(self.authorize_admin? ? :clients : :basic_data)   ... end

I was trying the conditional form for setting the current tab based on whether the logged_in? user was an "admin" or a plain "user". That did not work. I got the following exception:

NoMethodError in UsersController#edit

undefined method `authorize_admin?' for UsersController:Class in line 4 which is the current_tab method above. I do not fully understand why. The current_tab is a class method why can't it take an argument containing an instance method?

I got around the above issue by doing this:

class UsersController < ApplicationController

  before_filter :login_required   current_tab :clients

  def edit     self.class.current_tab :basic_data unless authorize_admin?   end   .. end

So at the method level, I override the current_tab based on desired condition using the authorize_admin? method. This works.

So my question in the above context is: how do you call an instance method as an argument to the class method?

Bharat   ... end

If you don't understand why this doesn't work, then you probably don't understand when this code runs. This code runs when the class is loaded from users_controller.rb. In particular self is the class UsersController, so you can't call authorize_admin? on it, since that is an instance method and you don't have an instance of UsersController.

In production this code only executes once (when the app starts), ie there is no request or current user - clearly you can't be doing user specific things at this point.

Fred