revises recent commit related to :uniq => true

activerecord/lib/active_record/associations.rb

@@ -889,7 +889,7 @@ module ClassMethods
       #   Specifies type of the source association used by <tt>has_many :through</tt> queries where the source
       #   association is a polymorphic +belongs_to+.
       # [:uniq]
-      #   If true, duplicates will be omitted from the collection. Works only in conjunction with <tt>:through</tt>.
+      #   If true, duplicates will be omitted from the collection. Useful in conjunction with <tt>:through</tt>.
       # [:readonly]
       #   If true, all the associated objects are readonly through the association.
       # [:validate]

railties/guides/source/association_basics.textile

@@ -1371,47 +1371,41 @@ The +:through+ option specifies a join model through which to perform the query.
 
 h6(#has_many-uniq). +:uniq+
 
-Specify the +:uniq => true+ option to remove duplicates from the collection. It only works with +:through+ option.
+Set the +:uniq+ option to true to keep the collection free of duplicates. This is mostly useful together with the +:through+ option.
 
 <ruby>
 class Person < ActiveRecord::Base
-  has_many :readers
-  has_many :posts, :through => :readers
-
-  def self.lab
-    person = Person.create(:name => 'john')
-    p = Post.create(:name => 'a1')
-    person.posts << p
-    person.posts << p
-    person.reload
-    puts person.posts.inspect #=> [#<Post id: 5, name: "a1">, #<Post id: 5, name: "a1">]
-    puts Reader.all.inspect #=> [#<Reader id: 12, person_id: 5, post_id: 5>, #<Reader id: 13, person_id: 5, post_id: 5>]
-  end
+  has_many :readings
+  has_many :posts, :through => :readings
 end
+
+person = Person.create(:name => 'john')
+post   = Post.create(:name => 'a1')
+person.posts << post
+person.posts << post
+person.posts.inspect # => [#<Post id: 5, name: "a1">, #<Post id: 5, name: "a1">]
+Reading.all.inspect  # => [#<Reading id: 12, person_id: 5, post_id: 5>, #<Reading id: 13, person_id: 5, post_id: 5>]
 </ruby>
 
-In the above case +readers+ table has two records and +person.posts+ brings out both of these records even though these records are basically pointing to the same +post+ record.
+In the above case there are two readings and +person.posts+ brings out both of them even though these records are pointing to the same post.
 
-Now let's add +uniq => true+ option.
+Now let's set +:uniq+ to true:
 
 <ruby>
 class Person
-  has_many :readers
-  has_many :posts, :through => :readers, :uniq => true
-
-  def self.experiment
-    person = Person.create(:name => 'honda')
-    p = Post.create(:name => 'a1')
-    person.posts << p
-    person.posts << p
-    person.reload
-    puts person.posts.inspect #=> [#<Post id: 7, name: "a1">] 
-    puts Reader.all.inspect #=> [#<Reader id: 16, person_id: 7, post_id: 7>, #<Reader id: 17, person_id: 7, post_id: 7>] 
-  end
+  has_many :readings
+  has_many :posts, :through => :readings, :uniq => true
 end
+
+person = Person.create(:name => 'honda')
+post   = Post.create(:name => 'a1')
+person.posts << post
+person.posts << post
+person.posts.inspect # => [#<Post id: 7, name: "a1">] 
+Reading.all.inspect  # => [#<Reading id: 16, person_id: 7, post_id: 7>, #<Reading id: 17, person_id: 7, post_id: 7>] 
 </ruby>
 
-In the above case +readers+ table still has two records. However +person.posts+ will show only one +post+ record because collection will load only +unique+ records.
+In the above case there are still two readings. However +person.posts+ shows only one post because collection loads only unique records.
 
 h6(#has_many-validate). +:validate+