Creates :slug from given :title when creating models if no :slug given

autoslug.rb

# autoslug.rb
#
# Usage:
#
# include Autoslug
# attr_slug :title [, :slug] [, &block]
#
# Creates :slug from given :title when creating models if no :slug given
# Uses parameterize by default or can run :title through a &block:
#
# include Autoslug
# attr_slug(:title) { |s| s.parameterize.tr('-', '') }
#

module Autoslug

  def self.included(base)
    def base.attr_slug(title_attr, slug_attr = :slug, &block )

      def create_slug(title_attr, slug_attr, &block)
        self.send("#{slug_attr}=", (
          if block_given?
            yield(self.send(title_attr))
          else
            self.send(title_attr).parameterize
          end
            )
        ) unless send(slug_attr)
      end

      self.send :after_initialize do
        create_slug(title_attr, slug_attr, &block)
      end

    end
  end

end