The "embedded actions" plugin 
=============================
Just like the traditional render :partial, embedded actions allow you to
refactor your views and extract presentation logic and templates into separate
files.
Unlike partials, embedded actions also let you define business logic to be
performed before the partial is included. That logic is encapsulated in the
already well understood metaphor of an action inside a controller.
So a simple call like
<%= embed_action :controller => "songs", :action => "top10" %>
lets you include an html fragment containing the top 10 songs into any of your
pages, regardless of which controller, action or view wants to do the including.
Additionally, embedded actions can provide caching of their results (allowing
for different parameters) just like page caching, but at the level of html
fragments. So your dynamic pages can still be rendered dynamically, but some of
the embedded actions can be cached (and expired) independently.
Just declare an action as 'cacheable' in a way similar to page caching, 
by invoking "caches_embedded" with the name of the action to cache.
class TestController < ApplicationController
  caches_embedded :user_list
  def user_list
    ...
  end
end
Cached fragments can be invalidated with calls to expires_embedded, but you must
remember to use the same set of parameters used to embed the cached action in
the first place.
Additionally, the underlying fragment caching mechanism can be passed 
an options hash in the following manner:
  caches_embedded :user_list, :ttl => 60.minutes
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Copyright (c) 2007 Sebastian Delmont <sd@notso.net> 
Copyright (c) 2007 StreetEasy / NMD Interactive <https://www.streeteasy.com/> 
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CONTRIBUTORS
- Sebastian Delmont <sd@notso.net>
- Jerret Taylor <jerrett@gmail.com>
- Ryan Barber <rfb@skyscraper.nu>
- Andreas Simon <asimon@med4you.de>
RELEASE HISTORY
1.0 - Oct 23 2007
  First widespread release.
1.0.1 - Oct 30 2007 
  Fixed bug that was causing a "Content-encoding: identity" to leak 
  to all requests.
1.0.2 - Nov 29 2007
  Fixed bug (thanks Jerret) that caused caching settings to leak 
  to actions with the same name in other controllers.
1.1 - Dec 4 2007
  Passthrough options for fragment caching (Ryan).
  Support for namespaced controllers in caching (Jerret). 
  Minor bug fixes.
1.1.1 - Feb 20 2008
  Allow symbol names for controllers and actions (Andreas)
  Fixed deprecated 'require_gem' in test environment (Andreas)