gistfile1.rb

  def textilize_description
    if changed.include?('description')
      self.description_html = textilize(self.description)
    end
  end

  def textilize(text)
    if text.blank?
      ""
    else
      doc = RedCloth.new(text || '')
      doc.filter_html = true
      doc.to_html
    end
  end