gistfile1.rb

  def self.allow(roles, options = {})
    class_eval do 
      def check_permission
        # Insert your application logic here
        if current_user.nil? or !current_user.roles.exists?(:id => roles)
          flash[:notice] = "Go away!"
          return check_and_redirect_to("/login")
        end
      end
    end

    before_filter :check_permission, options  
  end