gistfile1.rb

# ApplicationController
def render_sidebar_widget(path, item = nil)
  locals = {}
  locals = self.send(item) unless item.nil?
  render_to_string(:partial => path, :locals => locals).html_safe
end
helper_method :render_sidebar_widget

def reading_list
  set(:reading_items, ReadingItem.updated_desc.all)
  { :reading_items => @reading_items }
end

# View
<% render_sidebar_widget("reading_items/listing", :reading_list) %>