define_method_owns.rb

  # Meta-method to setup before_filters on controller
  # actions requiring various authorization levels.
  def self.must_be(role, options={})
    define_method "#{role}_required" do
      unless authorized?(role)
        if logged_in?
          redirect_to request.referer || root_url, :alert => "You must be an #{role} to access that page."
        else
          redirect_to login_path, :alert => "You must be logged in to access that page."
        end
      end
    end
    
    protected "#{role}_required"
    before_filter "#{role}_required".to_sym, options
  end