Add before_filter to pages controller from refinery engine

gistfile1.rb

require 'refinerycms'

module Refinery
  module MyEngine
    class Engine < Rails::Engine
      refinery.after_inclusion do
        ::PagesController.class_eval do
          before_filter :check_some_stuff, :only => :show
          def check_some_stuff
          end
        end
      end
    end
  end
end