=begin

  = Find Those With =

  A macro method for defining named_scopes for has_many owners.

  USAGE

  Find only those posts with comments:

    class Post < ActiveRecord::Base
      has_many :comments

      finds_those_with :comments
    end

    Post.with_comments

  DISCLAIMER

  I don't know what the crap I'm doing with SQL.

=end
ActiveRecord::Base.class_eval do
  def self.finds_those_with(name, options={})
    options[:using] ||= "with_#{name}"
    options[:model] ||= name.to_s.classify.constantize
    named_scope options[:using].to_sym,
      :include => name,
      :select => "#{table_name}.*",
      :conditions => "#{options[:model].table_name}.id IS NOT NULL"
  end
end