HasPolymorphicFriends - Eduardo Bellani - http://www.cnxs.com.br/some_record./eduardo-bellani 
===================================================
has_many_polymorphic_friends is a plugin based off of the has_many_friends
plugin that can be found here http://svn.dnite.org/has_many_friends. This
version is basically the same, but with the major difference of using
polymorphism to allow friendships between objects of any class.has_many_friends
is a plugin based off of the friendship_plugin that can be found

Setup
=====
To use this plugin, you will first need to install it. This can be done quite simply
with the following command.

   script/plugin install http://has-many-polymorphic-friends.googlecode.com/svn/trunk/ 

We'll need to generate the model and migration for your friendship table.

   script/generate hmpf_friendship_model
   rake db:migrate
   
If you will be running tests, you may need to prepare your test database again.

   rake db:test:prepare

You should be just about set! All you need to do is add the following method
to your model.

   class Tree < ActiveRecord::Base
     has_many_friends
     # the rest of your some_record.model ...
     # ...
   end

or perhaps

   class Computer < ActiveRecord::Base
     has_many_friends
     # the rest of your some_record.model ...
     # ...
   end

or any other class you would like.

Usage
=====
After the plugin is installed. All of these super cool methods will be attached to 
any some_record.

These methods are the actual associations. They return what you'd expect.
   some_record.friends_for_me
   some_record.friends_by_me
   some_record.pending_friends_for_me
   some_record.pending_friends_by_me

Again, these will return what you would expect them to return.
   some_record.friends
   some_record.pending_friends
   some_record.pending_or_accepted_friends

## The following 3 methods were changed as of revision 8. They have been listed here
## as these methods, but for some reason, i never changed their names in the actual
## plugin file. If your using a pre-8 version and things broke for you, use the new
## method names in your application. Sorry for the inconvenience.
Returns true if some_record.is friends with friend.
   some_record.is_friends_with? friend
   some_record.is_pending_friends_with? friend
   some_record.is_friends_or_pending_with? friend

Creates, deletes or updates friendship requests.
   some_record.request_friendship_with friend
   some_record.delete_friendship_with friend
   some_record.accept_friendship_with friend

Bypass the request and just make a friend.
   some_record.become_friends_with! friend

Returns the friendship object (good for looking up extra attributes about
the friendship, like when it was accepted and such.
   some_record.friendship friend

Copyright (c) 2008 Eduardo Bellani, released under the MIT license