Merge the has_finder gem, renamed as 'named_scope'. Closes #11404 [nkallen]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@9084 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

@@ -1,5 +1,19 @@
 *SVN*
 
+* Merge the has_finder gem, renamed as 'named_scope'.  #11404 [nkallen]
+
+  class Article < ActiveRecord::Base
+    has_finder :published, :conditions => {:published => true}
+    has_finder :popular, :conditions => ...
+  end
+
+  Article.published.paginate(:page => 1)
+  Article.published.popular.count
+  Article.popular.find(:first)
+  Article.popular.find(:all, :conditions => {...})
+
+  See http://pivots.pivotallabs.com/users/nick/blog/articles/284-hasfinder-it-s-now-easier-than-ever-to-create-complex-re-usable-sql-queries
+
 * Add has_one :through support.  #4756 [thechrisoshow]
 
 * Migrations: create_table supports primary_key_prefix_type.  #10314 [student, thechrisoshow]

activerecord/lib/active_record.rb

@@ -37,6 +37,7 @@ unless defined? ActiveSupport
 end
 
 require 'active_record/base'
+require 'active_record/named_scope'
 require 'active_record/observer'
 require 'active_record/query_cache'
 require 'active_record/validations'
@@ -64,6 +65,7 @@ ActiveRecord::Base.class_eval do
   include ActiveRecord::Observing
   include ActiveRecord::Timestamp
   include ActiveRecord::Associations
+  include ActiveRecord::NamedScope
   include ActiveRecord::AssociationPreload
   include ActiveRecord::Aggregations
   include ActiveRecord::Transactions

activerecord/lib/active_record/associations.rb

@@ -1133,7 +1133,7 @@ module ActiveRecord
             end
           end
         end
-
+        
         def add_multiple_associated_save_callbacks(association_name)
           method_name = "validate_associated_records_for_#{association_name}".to_sym
           ivar = "@#{association_name}"

activerecord/lib/active_record/associations/association_collection.rb

@@ -41,7 +41,7 @@ module ActiveRecord
         delete(@target)
         reset_target!
       end
-
+      
       # Calculate sum using SQL, not Enumerable
       def sum(*args)
         if block_given?
@@ -168,8 +168,10 @@ module ActiveRecord
             else
               super
             end
-          else
-            @reflection.klass.send(:with_scope, construct_scope) do
+          elsif @reflection.klass.scopes.include?(method)
+            @reflection.klass.scopes[method].call(self, *args)
+          else          
+            with_scope(construct_scope) do
               if block_given?
                 @reflection.klass.send(method, *args) { |*block_args| yield(*block_args) }
               else

activerecord/lib/active_record/associations/association_proxy.rb

@@ -119,6 +119,10 @@ module ActiveRecord
           )
         end
 
+        def with_scope(*args, &block)
+          @reflection.klass.send :with_scope, *args, &block
+        end
+          
       private
         def method_missing(method, *args)
           if load_target

activerecord/lib/active_record/associations/has_many_association.rb

@@ -167,7 +167,10 @@ module ActiveRecord
         def construct_scope
           create_scoping = {}
           set_belongs_to_association_for(create_scoping)
-          { :find => { :conditions => @finder_sql, :readonly => false, :order => @reflection.options[:order], :limit => @reflection.options[:limit] }, :create => create_scoping }
+          {
+            :find => { :conditions => @finder_sql, :readonly => false, :order => @reflection.options[:order], :limit => @reflection.options[:limit] },
+            :create => create_scoping
+          }
         end
     end
   end

activerecord/lib/active_record/associations/has_many_through_association.rb

@@ -139,8 +139,10 @@ module ActiveRecord
             else
               super
             end
+          elsif @reflection.klass.scopes.include?(method)
+            @reflection.klass.scopes[method].call(self, *args)
           else
-            @reflection.klass.send(:with_scope, construct_scope) do
+            with_scope construct_scope do
               if block_given?
                 @reflection.klass.send(method, *args) { |*block_args| yield(*block_args) }
               else

activerecord/lib/active_record/named_scope.rb

@@ -0,0 +1,128 @@
+module ActiveRecord
+  module NamedScope
+    # All subclasses of ActiveRecord::Base have two named_scopes:
+    # * <tt>all</tt>, which is similar to a <tt>find(:all)</tt> query, and
+    # * <tt>scoped</tt>, which allows for the creation of anonymous scopes, on the fly:
+    #
+    #   Shirt.scoped(:conditions => {:color => 'red'}).scoped(:include => :washing_instructions)
+    #
+    # These anonymous scopes tend to be useful when procedurally generating complex queries, where passing
+    # intermediate values (scopes) around as first-class objects is convenient.
+    def self.included(base)
+      base.class_eval do
+        extend ClassMethods
+        named_scope :all
+        named_scope :scoped, lambda { |scope| scope }
+      end
+    end
+
+    module ClassMethods
+      def scopes
+        read_inheritable_attribute(:scopes) || write_inheritable_attribute(:scopes, {})
+      end
+
+      # Adds a class method for retrieving and querying objects. A scope represents a narrowing of a database query,
+      # such as <tt>:conditions => {:color => :red}, :select => 'shirts.*', :include => :washing_instructions</tt>.
+      #
+      #   class Shirt < ActiveRecord::Base
+      #     named_scope :red, :conditions => {:color => 'red'}
+      #     named_scope :dry_clean_only, :joins => :washing_instructions, :conditions => ['washing_instructions.dry_clean_only = ?', true]
+      #   end
+      # 
+      # The above calls to <tt>named_scope</tt> define class methods <tt>Shirt.red</tt> and <tt>Shirt.dry_clean_only</tt>. <tt>Shirt.red</tt>, 
+      # in effect, represents the query <tt>Shirt.find(:all, :conditions => {:color => 'red'})</tt>.
+      #
+      # Unlike Shirt.find(...), however, the object returned by <tt>Shirt.red</tt> is not an Array; it resembles the association object
+      # constructed by a <tt>has_many</tt> declaration. For instance, you can invoke <tt>Shirt.red.find(:first)</tt>, <tt>Shirt.red.count</tt>,
+      # <tt>Shirt.red.find(:all, :conditions => {:size => 'small'})</tt>. Also, just
+      # as with the association objects, name scopes acts like an Array, implementing Enumerable; <tt>Shirt.red.each(&block)</tt>,
+      # <tt>Shirt.red.first</tt>, and <tt>Shirt.red.inject(memo, &block)</tt> all behave as if Shirt.red really were an Array.
+      #
+      # These named scopes are composable. For instance, <tt>Shirt.red.dry_clean_only</tt> will produce all shirts that are both red and dry clean only.
+      # Nested finds and calculations also work with these compositions: <tt>Shirt.red.dry_clean_only.count</tt> returns the number of garments
+      # for which these criteria obtain. Similarly with <tt>Shirt.red.dry_clean_only.average(:thread_count)</tt>.
+      #
+      # All scopes are available as class methods on the ActiveRecord descendent upon which the scopes were defined. But they are also available to
+      # <tt>has_many</tt> associations. If,
+      #
+      #   class Person < ActiveRecord::Base
+      #     has_many :shirts
+      #   end
+      #
+      # then <tt>elton.shirts.red.dry_clean_only</tt> will return all of Elton's red, dry clean
+      # only shirts.
+      #
+      # Named scopes can also be procedural.
+      #
+      #   class Shirt < ActiveRecord::Base
+      #     named_scope :colored, lambda { |color|
+      #       { :conditions => { :color => color } }
+      #     }
+      #   end
+      #
+      # In this example, <tt>Shirt.colored('puce')</tt> finds all puce shirts.
+      #
+      # Named scopes can also have extensions, just as with <tt>has_many</tt> declarations:
+      #
+      #   class Shirt < ActiveRecord::Base
+      #     named_scope :red, :conditions => {:color => 'red'} do
+      #       def dom_id
+      #         'red_shirts'
+      #       end
+      #     end
+      #   end
+      #
+      def named_scope(name, options = {}, &block)
+        scopes[name] = lambda do |parent_scope, *args|
+          Scope.new(parent_scope, case options
+            when Hash
+              options
+            when Proc
+              options.call(*args)
+          end, &block)
+        end
+        (class << self; self end).instance_eval do
+          define_method name do |*args|
+            scopes[name].call(self, *args)
+          end
+        end
+      end
+    end
+    
+    class Scope
+      attr_reader :proxy_scope, :proxy_options
+      [].methods.each { |m| delegate m, :to => :proxy_found unless m =~ /(^__|^nil\?|^send|class|extend|find|count|sum|average|maximum|minimum|paginate)/ }
+      delegate :scopes, :with_scope, :to => :proxy_scope
+
+      def initialize(proxy_scope, options, &block)
+        [options[:extend]].flatten.each { |extension| extend extension } if options[:extend]
+        extend Module.new(&block) if block_given?
+        @proxy_scope, @proxy_options = proxy_scope, options.except(:extend)
+      end
+
+      def reload
+        load_found; self
+      end
+
+      protected
+      def proxy_found
+        @found || load_found
+      end
+
+      private
+      def method_missing(method, *args, &block)
+        if scopes.include?(method)
+          scopes[method].call(self, *args)
+        else
+          with_scope :find => proxy_options do
+            proxy_scope.send(method, *args, &block)
+          end
+        end
+      end
+
+      def load_found
+        @found = find(:all)
+      end
+    end
+  end
+end

activerecord/test/cases/associations/cascaded_eager_loading_test.rb

@@ -61,16 +61,17 @@ class CascadedEagerLoadingTest < ActiveRecord::TestCase
 
   def test_eager_association_loading_with_has_many_sti
     topics = Topic.find(:all, :include => :replies, :order => 'topics.id')
-    assert_equal topics(:first, :second), topics
+    first, second, = topics(:first).replies.size, topics(:second).replies.size
     assert_no_queries do
-      assert_equal 1, topics[0].replies.size
-      assert_equal 0, topics[1].replies.size
+      assert_equal first, topics[0].replies.size
+      assert_equal second, topics[1].replies.size
     end
   end
 
   def test_eager_association_loading_with_belongs_to_sti
     replies = Reply.find(:all, :include => :topic, :order => 'topics.id')
-    assert_equal [topics(:second)], replies
+    assert replies.include?(topics(:second))
+    assert !replies.include?(topics(:first))
     assert_equal topics(:first), assert_no_queries { replies.first.topic }
   end
 

activerecord/test/cases/base_test.rb

@@ -477,7 +477,7 @@ class BasicsTest < ActiveRecord::TestCase
 
   def test_load
     topics = Topic.find(:all, :order => 'id')
-    assert_equal(2, topics.size)
+    assert_equal(4, topics.size)
     assert_equal(topics(:first).title, topics.first.title)
   end
 
@@ -549,10 +549,11 @@ class BasicsTest < ActiveRecord::TestCase
   end
 
   def test_destroy_all
-    assert_equal 2, Topic.count
-
-    Topic.destroy_all "author_name = 'Mary'"
-    assert_equal 1, Topic.count
+    original_count = Topic.count
+    topics_by_mary = Topic.count(:conditions => mary = "author_name = 'Mary'")
+    
+    Topic.destroy_all mary
+    assert_equal original_count - topics_by_mary, Topic.count
   end
 
   def test_destroy_many
@@ -562,8 +563,9 @@ class BasicsTest < ActiveRecord::TestCase
   end
 
   def test_delete_many
-    Topic.delete([1, 2])
-    assert_equal 0, Topic.count
+    original_count = Topic.count
+    Topic.delete(deleting = [1, 2])
+    assert_equal original_count - deleting.size, Topic.count
   end
 
   def test_boolean_attributes
@@ -588,21 +590,21 @@ class BasicsTest < ActiveRecord::TestCase
   end
 
   def test_update_all
-    assert_equal 2, Topic.update_all("content = 'bulk updated!'")
+    assert_equal Topic.count, Topic.update_all("content = 'bulk updated!'")
     assert_equal "bulk updated!", Topic.find(1).content
     assert_equal "bulk updated!", Topic.find(2).content
 
-    assert_equal 2, Topic.update_all(['content = ?', 'bulk updated again!'])
+    assert_equal Topic.count, Topic.update_all(['content = ?', 'bulk updated again!'])
     assert_equal "bulk updated again!", Topic.find(1).content
     assert_equal "bulk updated again!", Topic.find(2).content
 
-    assert_equal 2, Topic.update_all(['content = ?', nil])
+    assert_equal Topic.count, Topic.update_all(['content = ?', nil])
     assert_nil Topic.find(1).content
   end
 
   def test_update_all_with_hash
     assert_not_nil Topic.find(1).last_read
-    assert_equal 2, Topic.update_all(:content => 'bulk updated with hash!', :last_read => nil)
+    assert_equal Topic.count, Topic.update_all(:content => 'bulk updated with hash!', :last_read => nil)
     assert_equal "bulk updated with hash!", Topic.find(1).content
     assert_equal "bulk updated with hash!", Topic.find(2).content
     assert_nil Topic.find(1).last_read
@@ -637,7 +639,9 @@ class BasicsTest < ActiveRecord::TestCase
   end
 
   def test_delete_all
-    assert_equal 2, Topic.delete_all
+    assert Topic.count > 0
+    
+    assert_equal Topic.count, Topic.delete_all
   end
 
   def test_update_by_condition
@@ -804,17 +808,17 @@ class BasicsTest < ActiveRecord::TestCase
 
   def test_update_attributes!
     reply = Reply.find(2)
-    assert_equal "The Second Topic's of the day", reply.title
+    assert_equal "The Second Topic of the day", reply.title
     assert_equal "Have a nice day", reply.content
 
-    reply.update_attributes!("title" => "The Second Topic's of the day updated", "content" => "Have a nice evening")
+    reply.update_attributes!("title" => "The Second Topic of the day updated", "content" => "Have a nice evening")
     reply.reload
-    assert_equal "The Second Topic's of the day updated", reply.title
+    assert_equal "The Second Topic of the day updated", reply.title
     assert_equal "Have a nice evening", reply.content
 
-    reply.update_attributes!(:title => "The Second Topic's of the day", :content => "Have a nice day")
+    reply.update_attributes!(:title => "The Second Topic of the day", :content => "Have a nice day")
     reply.reload
-    assert_equal "The Second Topic's of the day", reply.title
+    assert_equal "The Second Topic of the day", reply.title
     assert_equal "Have a nice day", reply.content
 
     assert_raise(ActiveRecord::RecordInvalid) { reply.update_attributes!(:title => nil, :content => "Have a nice evening") }
@@ -1770,7 +1774,7 @@ class BasicsTest < ActiveRecord::TestCase
     xml = topics(:first).to_xml(:indent => 0, :skip_instruct => true, :include => :replies, :except => :replies_count)
     assert_equal "<topic>", xml.first(7)
     assert xml.include?(%(<replies type="array"><reply>))
-    assert xml.include?(%(<title>The Second Topic's of the day</title>))
+    assert xml.include?(%(<title>The Second Topic of the day</title>))
   end
 
   def test_array_to_xml_including_has_many_association

activerecord/test/cases/finder_test.rb

@@ -542,7 +542,7 @@ class FinderTest < ActiveRecord::TestCase
   end
 
   def test_find_all_by_array_attribute
-    assert_equal 2, Topic.find_all_by_title(["The First Topic", "The Second Topic's of the day"]).size
+    assert_equal 2, Topic.find_all_by_title(["The First Topic", "The Second Topic of the day"]).size
   end
 
   def test_find_all_by_boolean_attribute
@@ -551,7 +551,7 @@ class FinderTest < ActiveRecord::TestCase
     assert topics.include?(topics(:first))
 
     topics = Topic.find_all_by_approved(true)
-    assert_equal 1, topics.size
+    assert_equal 3, topics.size
     assert topics.include?(topics(:second))
   end
 
@@ -563,8 +563,8 @@ class FinderTest < ActiveRecord::TestCase
 
   def test_find_all_by_nil_attribute
     topics = Topic.find_all_by_last_read nil
-    assert_equal 1, topics.size
-    assert_nil topics[0].last_read
+    assert_equal 3, topics.size
+    assert topics.collect(&:last_read).all?(&:nil?)
   end
 
   def test_find_by_nil_and_not_nil_attributes

activerecord/test/cases/fixtures_test.rb

@@ -123,7 +123,7 @@ class FixturesTest < ActiveRecord::TestCase
   end
 
   def test_complete_instantiation
-    assert_equal 2, @topics.size
+    assert_equal 4, @topics.size
     assert_equal "The First Topic", @first.title
   end
 

activerecord/test/cases/lifecycle_test.rb

@@ -68,9 +68,9 @@ class LifecycleTest < ActiveRecord::TestCase
   fixtures :topics, :developers
 
   def test_before_destroy
-    assert_equal 2, Topic.count
-    Topic.find(1).destroy
-    assert_equal 0, Topic.count
+    original_count = Topic.count
+    (topic_to_be_destroyed = Topic.find(1)).destroy
+    assert_equal original_count - (1 + topic_to_be_destroyed.replies.size), Topic.count
   end
 
   def test_after_save

activerecord/test/cases/named_scope_test.rb

@@ -0,0 +1,116 @@
+require "cases/helper"
+require 'models/post'
+require 'models/topic'
+require 'models/comment'
+require 'models/reply'
+require 'models/author'
+
+class NamedScopeTest < ActiveRecord::TestCase
+  fixtures :posts, :authors, :topics
+  
+  def test_implements_enumerable
+    assert !Topic.find(:all).empty?
+    
+    assert_equal Topic.find(:all),   Topic.all
+    assert_equal Topic.find(:all),   Topic.all.collect
+    assert_equal Topic.find(:first), Topic.all.first
+    assert_equal Topic.find(:all),   Topic.all.each { |i| i }
+  end
+  
+  def test_found_items_are_cached
+    Topic.columns
+    all_posts = Topic.all
+    
+    assert_queries(1) do
+      all_posts.collect
+      all_posts.collect
+    end
+  end
+  
+  def test_reload_expires_cache_of_found_items
+    all_posts = Topic.all
+    all_posts.inspect
+    
+    new_post = Topic.create!
+    assert !all_posts.include?(new_post)
+    assert all_posts.reload.include?(new_post)
+  end
+  
+  def test_delegates_finds_and_calculations_to_the_base_class
+    assert !Topic.find(:all).empty?
+    
+    assert_equal Topic.find(:all),               Topic.all.find(:all)
+    assert_equal Topic.find(:first),             Topic.all.find(:first)
+    assert_equal Topic.count,                    Topic.all.count
+    assert_equal Topic.average(:replies_count), Topic.all.average(:replies_count)
+  end
+  
+  def test_subclasses_inherit_scopes
+    assert Topic.scopes.include?(:all)
+    
+    assert Reply.scopes.include?(:all)
+    assert_equal Reply.find(:all), Reply.all
+  end
+  
+  def test_scopes_with_options_limit_finds_to_those_matching_the_criteria_specified
+    assert !Topic.find(:all, :conditions => {:approved => true}).empty?
+    
+    assert_equal Topic.find(:all, :conditions => {:approved => true}), Topic.approved
+    assert_equal Topic.count(:conditions => {:approved => true}), Topic.approved.count
+  end
+  
+  def test_scopes_are_composable
+    assert_equal (approved = Topic.find(:all, :conditions => {:approved => true})), Topic.approved
+    assert_equal (replied = Topic.find(:all, :conditions => 'replies_count > 0')), Topic.replied
+    assert !(approved == replied)    
+    assert !(approved & replied).empty?
+    
+    assert_equal approved & replied, Topic.approved.replied
+  end
+
+  def test_procedural_scopes
+    topics_written_before_the_third = Topic.find(:all, :conditions => ['written_on < ?', topics(:third).written_on])
+    topics_written_before_the_second = Topic.find(:all, :conditions => ['written_on < ?', topics(:second).written_on])
+    assert_not_equal topics_written_before_the_second, topics_written_before_the_third
+    
+    assert_equal topics_written_before_the_third, Topic.written_before(topics(:third).written_on)
+    assert_equal topics_written_before_the_second, Topic.written_before(topics(:second).written_on)
+  end
+  
+  def test_extensions
+    assert_equal 1, Topic.anonymous_extension.one
+    assert_equal 2, Topic.named_extension.two
+  end
+  
+  def test_multiple_extensions
+    assert_equal 2, Topic.multiple_extensions.extension_two
+    assert_equal 1, Topic.multiple_extensions.extension_one    
+  end
+  
+  def test_has_many_associations_have_access_to_named_scopes
+    assert_not_equal Post.containing_the_letter_a, authors(:david).posts
+    assert !Post.containing_the_letter_a.empty?
+        
+    assert_equal authors(:david).posts & Post.containing_the_letter_a, authors(:david).posts.containing_the_letter_a
+  end
+  
+  def test_has_many_through_associations_have_access_to_named_scopes
+    assert_not_equal Comment.containing_the_letter_e, authors(:david).posts
+    assert !Comment.containing_the_letter_e.empty?
+        
+    assert_equal authors(:david).comments & Comment.containing_the_letter_e, authors(:david).comments.containing_the_letter_e
+  end
+  
+  def test_active_records_have_scope_named__all__
+    assert !Topic.find(:all).empty?
+        
+    assert_equal Topic.find(:all), Topic.all
+  end
+  
+  def test_active_records_have_scope_named__scoped__
+    assert !Topic.find(:all, scope = {:conditions => "content LIKE '%Have%'"}).empty?
+    
+    assert_equal Topic.find(:all, scope), Topic.scoped(scope)
+  end
+    
+end

activerecord/test/cases/validations_test.rb

@@ -428,7 +428,7 @@ class ValidationsTest < ActiveRecord::TestCase
     assert_nil t2.errors.on(:title)
     assert t2.errors.on(:parent_id)
 
-    t2.parent_id = 3
+    t2.parent_id = 4
     assert t2.save, "Should now save t2 as unique"
 
     t2.parent_id = nil

activerecord/test/fixtures/topics.yml

@@ -12,11 +12,31 @@ first:
 
 second:
   id: 2
-  title: The Second Topic's of the day
+  title: The Second Topic of the day
   author_name: Mary
-  written_on: 2003-07-15t15:28:00.0099+01:00
+  written_on: 2004-07-15t15:28:00.0099+01:00
   content: Have a nice day
   approved: true
   replies_count: 0
   parent_id: 1
   type: Reply
+
+third:
+  id: 3
+  title: The Third Topic of the day
+  author_name: Nick
+  written_on: 2005-07-15t15:28:00.0099+01:00
+  content: I'm a troll
+  approved: true
+  replies_count: 1
+
+fourth:
+  id: 4
+  title: The Fourth Topic of the day
+  author_name: Carl
+  written_on: 2006-07-15t15:28:00.0099+01:00
+  content: Why not?
+  approved: true
+  type: Reply
+  parent_id: 3
+

activerecord/test/models/author.rb

@@ -3,6 +3,7 @@ class Author < ActiveRecord::Base
   has_many :posts_with_comments, :include => :comments, :class_name => "Post"
   has_many :posts_with_categories, :include => :categories, :class_name => "Post"
   has_many :posts_with_comments_and_categories, :include => [ :comments, :categories ], :order => "posts.id", :class_name => "Post"
+  has_many :posts_containing_the_letter_a, :class_name => "Post"
   has_many :posts_with_extension, :class_name => "Post" do #, :extend => ProxyTestExtension
     def testing_proxy_owner
       proxy_owner
@@ -15,6 +16,7 @@ class Author < ActiveRecord::Base
     end
   end
   has_many :comments, :through => :posts
+  has_many :comments_containing_the_letter_e, :through => :posts, :source => :comments
   has_many :comments_desc, :through => :posts, :source => :comments, :order => 'comments.id DESC'
   has_many :limited_comments, :through => :posts, :source => :comments, :limit => 1
   has_many :funky_comments, :through => :posts, :source => :comments

activerecord/test/models/comment.rb

@@ -1,4 +1,6 @@
 class Comment < ActiveRecord::Base
+  named_scope :containing_the_letter_e, :conditions => "comments.body LIKE '%e%'"
+  
   belongs_to :post, :counter_cache => true
 
   def self.what_are_you

activerecord/test/models/post.rb

@@ -1,4 +1,6 @@
 class Post < ActiveRecord::Base
+  named_scope :containing_the_letter_a, :conditions => "body LIKE '%a%'"
+  
   belongs_to :author do
     def greeting
       "hello"

activerecord/test/models/topic.rb

@@ -1,4 +1,32 @@
 class Topic < ActiveRecord::Base
+  named_scope :written_before, lambda { |time|
+    { :conditions => ['written_on < ?', time] }
+  }
+  named_scope :approved, :conditions => {:approved => true}
+  named_scope :replied, :conditions => ['replies_count > 0']
+  named_scope :anonymous_extension do
+    def one
+      1
+    end
+  end
+  module NamedExtension
+    def two
+      2
+    end
+  end
+  module MultipleExtensionOne
+    def extension_one
+      1
+    end
+  end
+  module MultipleExtensionTwo
+    def extension_two
+      2
+    end
+  end
+  named_scope :named_extension, :extend => NamedExtension
+  named_scope :multiple_extensions, :extend => [MultipleExtensionTwo, MultipleExtensionOne]
+  
   has_many :replies, :dependent => :destroy, :foreign_key => "parent_id"
   serialize :content