class Movie < ActiveRecord::Base
  def self.with_playing 
    with_scope :find => { :conditions => [ ‘state = ? AND visible = ?’, NOW_PLAYING, true ] } do 
      yield 
    end 
  end
end

class MovieController < ApplicationController 
  def director 
    Movie.with_playing do 
      @director = Movie.find_by_id(params[:movie_id]).director 
    end 
  end 
end

class Movie < ActiveRecord::Base
  def self.find_playing(*args)
    with_playing do
      find(*args)
    end
  end
 
  def self.find_playing_by_id
    with_playing do
      find_by_id(*args)
    end
  end
 
  def self.with_playing 
    with_scope :find => { :conditions => [ ‘state = ? AND visible = ?’, NOW_PLAYING, true ] } do 
      yield 
    end 
  end
end

def self.method_missing(method, *args, &block)
  if method.to_s =~ /^find_(all_)?playing_by/
    with_playing do
      super(method.to_s.sub('playing_', ''), *args, &block)
    end
  else
    super(method, *args, &block)
  end
end