Move DefaultScope and NamedScope under Scoping

7 files changed, 357 insertions, 342 deletions

diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index de73715e35..2463f3951f 100644
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -58,7 +58,6 @@ module ActiveRecord
     autoload :Base
     autoload :Callbacks
     autoload :CounterCache
-    autoload :DefaultScope
     autoload :DynamicMatchers
     autoload :DynamicFinderMatch
     autoload :DynamicScopeMatch
@@ -69,7 +68,6 @@ module ActiveRecord
     autoload :Migration
     autoload :Migrator, 'active_record/migration'
     autoload :ModelSchema
-    autoload :NamedScope
     autoload :NestedAttributes
     autoload :Observer
     autoload :Persistence
@@ -129,6 +127,15 @@ module ActiveRecord
     end
   end
 
+  module Scoping
+    extend ActiveSupport::Autoload
+
+    eager_autoload do
+      autoload :Named
+      autoload :Default
+    end
+  end
+
   autoload :TestCase
   autoload :TestFixtures, 'active_record/fixtures'
 end
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 819c616927..b479c403a7 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -686,7 +686,6 @@ module ActiveRecord #:nodoc:
     extend Translation
     include Inheritance
     include Scoping
-    include DefaultScope
     extend DynamicMatchers
     include Sanitization
     include Integration
@@ -697,7 +696,7 @@ module ActiveRecord #:nodoc:
     include Locking::Optimistic, Locking::Pessimistic
     include AttributeMethods
     include Callbacks, ActiveModel::Observing, Timestamp
-    include Associations, NamedScope
+    include Associations
     include IdentityMap
     include ActiveModel::SecurePassword
     include Explain
diff --git a/activerecord/lib/active_record/default_scope.rb b/activerecord/lib/active_record/default_scope.rb
deleted file mode 100644
index dd637ad6c5..0000000000
--- a/activerecord/lib/active_record/default_scope.rb
+++ /dev/null
@@ -1,138 +0,0 @@
-require 'active_support/concern'
-
-module ActiveRecord
-  module DefaultScope
-    extend ActiveSupport::Concern
-
-    included do
-      # Stores the default scope for the class
-      class_attribute :default_scopes, :instance_writer => false
-      self.default_scopes = []
-    end
-
-    module ClassMethods
-      # Returns a scope for this class without taking into account the default_scope.
-      #
-      #   class Post < ActiveRecord::Base
-      #     def self.default_scope
-      #       where :published => true
-      #     end
-      #   end
-      #
-      #   Post.all          # Fires "SELECT * FROM posts WHERE published = true"
-      #   Post.unscoped.all # Fires "SELECT * FROM posts"
-      #
-      # This method also accepts a block meaning that all queries inside the block will
-      # not use the default_scope:
-      #
-      #   Post.unscoped {
-      #     Post.limit(10) # Fires "SELECT * FROM posts LIMIT 10"
-      #   }
-      #
-      # It is recommended to use block form of unscoped because chaining unscoped with <tt>scope</tt>
-      # does not work. Assuming that <tt>published</tt> is a <tt>scope</tt> following two statements are same.
-      #
-      # Post.unscoped.published
-      # Post.published
-      def unscoped #:nodoc:
-        block_given? ? relation.scoping { yield } : relation
-      end
-
-      def before_remove_const #:nodoc:
-        self.current_scope = nil
-      end
-
-      protected
-
-      # Use this macro in your model to set a default scope for all operations on
-      # the model.
-      #
-      #   class Article < ActiveRecord::Base
-      #     default_scope where(:published => true)
-      #   end
-      #
-      #   Article.all # => SELECT * FROM articles WHERE published = true
-      #
-      # The <tt>default_scope</tt> is also applied while creating/building a record. It is not
-      # applied while updating a record.
-      #
-      #   Article.new.published    # => true
-      #   Article.create.published # => true
-      #
-      # You can also use <tt>default_scope</tt> with a block, in order to have it lazily evaluated:
-      #
-      #   class Article < ActiveRecord::Base
-      #     default_scope { where(:published_at => Time.now - 1.week) }
-      #   end
-      #
-      # (You can also pass any object which responds to <tt>call</tt> to the <tt>default_scope</tt>
-      # macro, and it will be called when building the default scope.)
-      #
-      # If you use multiple <tt>default_scope</tt> declarations in your model then they will
-      # be merged together:
-      #
-      #   class Article < ActiveRecord::Base
-      #     default_scope where(:published => true)
-      #     default_scope where(:rating => 'G')
-      #   end
-      #
-      #   Article.all # => SELECT * FROM articles WHERE published = true AND rating = 'G'
-      #
-      # This is also the case with inheritance and module includes where the parent or module
-      # defines a <tt>default_scope</tt> and the child or including class defines a second one.
-      #
-      # If you need to do more complex things with a default scope, you can alternatively
-      # define it as a class method:
-      #
-      #   class Article < ActiveRecord::Base
-      #     def self.default_scope
-      #       # Should return a scope, you can call 'super' here etc.
-      #     end
-      #   end
-      def default_scope(scope = {})
-        scope = Proc.new if block_given?
-        self.default_scopes = default_scopes + [scope]
-      end
-
-      def build_default_scope #:nodoc:
-        if method(:default_scope).owner != DefaultScope::ClassMethods
-          evaluate_default_scope { default_scope }
-        elsif default_scopes.any?
-          evaluate_default_scope do
-            default_scopes.inject(relation) do |default_scope, scope|
-              if scope.is_a?(Hash)
-                default_scope.apply_finder_options(scope)
-              elsif !scope.is_a?(Relation) && scope.respond_to?(:call)
-                default_scope.merge(scope.call)
-              else
-                default_scope.merge(scope)
-              end
-            end
-          end
-        end
-      end
-
-      def ignore_default_scope? #:nodoc:
-        Thread.current["#{self}_ignore_default_scope"]
-      end
-
-      def ignore_default_scope=(ignore) #:nodoc:
-        Thread.current["#{self}_ignore_default_scope"] = ignore
-      end
-
-      # The ignore_default_scope flag is used to prevent an infinite recursion situation where
-      # a default scope references a scope which has a default scope which references a scope...
-      def evaluate_default_scope
-        return if ignore_default_scope?
-
-        begin
-          self.ignore_default_scope = true
-          yield
-        ensure
-          self.ignore_default_scope = false
-        end
-      end
-
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/named_scope.rb b/activerecord/lib/active_record/named_scope.rb
deleted file mode 100644
index 0313abe456..0000000000
--- a/activerecord/lib/active_record/named_scope.rb
+++ /dev/null
@@ -1,200 +0,0 @@
-require 'active_support/core_ext/array'
-require 'active_support/core_ext/hash/except'
-require 'active_support/core_ext/kernel/singleton_class'
-require 'active_support/core_ext/object/blank'
-require 'active_support/core_ext/class/attribute'
-
-module ActiveRecord
-  # = Active Record Named \Scopes
-  module NamedScope
-    extend ActiveSupport::Concern
-
-    module ClassMethods
-      # Returns an anonymous \scope.
-      #
-      #   posts = Post.scoped
-      #   posts.size # Fires "select count(*) from  posts" and returns the count
-      #   posts.each {|p| puts p.name } # Fires "select * from posts" and loads post objects
-      #
-      #   fruits = Fruit.scoped
-      #   fruits = fruits.where(:color => 'red') if options[:red_only]
-      #   fruits = fruits.limit(10) if limited?
-      #
-      # Anonymous \scopes tend to be useful when procedurally generating complex
-      # queries, where passing intermediate values (\scopes) around as first-class
-      # objects is convenient.
-      #
-      # You can define a \scope that applies to all finders using
-      # ActiveRecord::Base.default_scope.
-      def scoped(options = nil)
-        if options
-          scoped.apply_finder_options(options)
-        else
-          if current_scope
-            current_scope.clone
-          else
-            scope = relation.clone
-            scope.default_scoped = true
-            scope
-          end
-        end
-      end
-
-      ##
-      # Collects attributes from scopes that should be applied when creating
-      # an AR instance for the particular class this is called on.
-      def scope_attributes # :nodoc:
-        if current_scope
-          current_scope.scope_for_create
-        else
-          scope = relation.clone
-          scope.default_scoped = true
-          scope.scope_for_create
-        end
-      end
-
-      ##
-      # Are there default attributes associated with this scope?
-      def scope_attributes? # :nodoc:
-        current_scope || default_scopes.any?
-      end
-
-      # Adds a class method for retrieving and querying objects. A \scope represents a narrowing of a database query,
-      # such as <tt>where(:color => :red).select('shirts.*').includes(:washing_instructions)</tt>.
-      #
-      #   class Shirt < ActiveRecord::Base
-      #     scope :red, where(:color => 'red')
-      #     scope :dry_clean_only, joins(:washing_instructions).where('washing_instructions.dry_clean_only = ?', true)
-      #   end
-      #
-      # The above calls to <tt>scope</tt> define class methods Shirt.red and Shirt.dry_clean_only. Shirt.red,
-      # in effect, represents the query <tt>Shirt.where(:color => 'red')</tt>.
-      #
-      # Note that this is simply 'syntactic sugar' for defining an actual class method:
-      #
-      #   class Shirt < ActiveRecord::Base
-      #     def self.red
-      #       where(:color => 'red')
-      #     end
-      #   end
-      #
-      # Unlike <tt>Shirt.find(...)</tt>, however, the object returned by Shirt.red 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.first</tt>, <tt>Shirt.red.count</tt>, <tt>Shirt.red.where(:size => 'small')</tt>.
-      # Also, just as with the association objects, named \scopes act 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 was 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::Base descendant 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
-      #     scope :colored, lambda { |color| where(:color => color) }
-      #   end
-      #
-      # In this example, <tt>Shirt.colored('puce')</tt> finds all puce shirts.
-      #
-      # On Ruby 1.9 you can use the 'stabby lambda' syntax:
-      #
-      #   scope :colored, ->(color) { where(:color => color) }
-      #
-      # Note that scopes defined with \scope will be evaluated when they are defined, rather than
-      # when they are used. For example, the following would be incorrect:
-      #
-      #   class Post < ActiveRecord::Base
-      #     scope :recent, where('published_at >= ?', Time.now - 1.week)
-      #   end
-      #
-      # The example above would be 'frozen' to the <tt>Time.now</tt> value when the <tt>Post</tt>
-      # class was defined, and so the resultant SQL query would always be the same. The correct
-      # way to do this would be via a lambda, which will re-evaluate the scope each time
-      # it is called:
-      #
-      #   class Post < ActiveRecord::Base
-      #     scope :recent, lambda { where('published_at >= ?', Time.now - 1.week) }
-      #   end
-      #
-      # Named \scopes can also have extensions, just as with <tt>has_many</tt> declarations:
-      #
-      #   class Shirt < ActiveRecord::Base
-      #     scope :red, where(:color => 'red') do
-      #       def dom_id
-      #         'red_shirts'
-      #       end
-      #     end
-      #   end
-      #
-      # Scopes can also be used while creating/building a record.
-      #
-      #   class Article < ActiveRecord::Base
-      #     scope :published, where(:published => true)
-      #   end
-      #
-      #   Article.published.new.published    # => true
-      #   Article.published.create.published # => true
-      #
-      # Class methods on your model are automatically available
-      # on scopes. Assuming the following setup:
-      #
-      #   class Article < ActiveRecord::Base
-      #     scope :published, where(:published => true)
-      #     scope :featured, where(:featured => true)
-      #
-      #     def self.latest_article
-      #       order('published_at desc').first
-      #     end
-      #
-      #     def self.titles
-      #       map(&:title)
-      #     end
-      #
-      #   end
-      #
-      # We are able to call the methods like this:
-      #
-      #   Article.published.featured.latest_article
-      #   Article.featured.titles
-
-      def scope(name, scope_options = {})
-        name = name.to_sym
-        valid_scope_name?(name)
-        extension = Module.new(&Proc.new) if block_given?
-
-        scope_proc = lambda do |*args|
-          options = scope_options.respond_to?(:call) ? scope_options.call(*args) : scope_options
-          options = scoped.apply_finder_options(options) if options.is_a?(Hash)
-
-          relation = scoped.merge(options)
-
-          extension ? relation.extending(extension) : relation
-        end
-
-        singleton_class.send(:redefine_method, name, &scope_proc)
-      end
-
-    protected
-
-      def valid_scope_name?(name)
-        if respond_to?(name, true)
-          logger.warn "Creating scope :#{name}. " \
-                      "Overwriting existing method #{self.name}.#{name}."
-        end
-      end
-    end
-  end
-end
diff --git a/activerecord/lib/active_record/scoping.rb b/activerecord/lib/active_record/scoping.rb
index 50cd7d77e9..a8f5e96190 100644
--- a/activerecord/lib/active_record/scoping.rb
+++ b/activerecord/lib/active_record/scoping.rb
@@ -4,6 +4,11 @@ module ActiveRecord
   module Scoping
     extend ActiveSupport::Concern
 
+    included do
+      include Default
+      include Named
+    end
+
     module ClassMethods
       # with_scope lets you apply options to inner block incrementally. It takes a hash and the keys must be
       # <tt>:find</tt> or <tt>:create</tt>. <tt>:find</tt> parameter is <tt>Relation</tt> while
diff --git a/activerecord/lib/active_record/scoping/default.rb b/activerecord/lib/active_record/scoping/default.rb
new file mode 100644
index 0000000000..9840cbccae
--- /dev/null
+++ b/activerecord/lib/active_record/scoping/default.rb
@@ -0,0 +1,140 @@
+require 'active_support/concern'
+
+module ActiveRecord
+  module Scoping
+    module Default
+      extend ActiveSupport::Concern
+
+      included do
+        # Stores the default scope for the class
+        class_attribute :default_scopes, :instance_writer => false
+        self.default_scopes = []
+      end
+
+      module ClassMethods
+        # Returns a scope for this class without taking into account the default_scope.
+        #
+        #   class Post < ActiveRecord::Base
+        #     def self.default_scope
+        #       where :published => true
+        #     end
+        #   end
+        #
+        #   Post.all          # Fires "SELECT * FROM posts WHERE published = true"
+        #   Post.unscoped.all # Fires "SELECT * FROM posts"
+        #
+        # This method also accepts a block meaning that all queries inside the block will
+        # not use the default_scope:
+        #
+        #   Post.unscoped {
+        #     Post.limit(10) # Fires "SELECT * FROM posts LIMIT 10"
+        #   }
+        #
+        # It is recommended to use block form of unscoped because chaining unscoped with <tt>scope</tt>
+        # does not work. Assuming that <tt>published</tt> is a <tt>scope</tt> following two statements are same.
+        #
+        # Post.unscoped.published
+        # Post.published
+        def unscoped #:nodoc:
+          block_given? ? relation.scoping { yield } : relation
+        end
+
+        def before_remove_const #:nodoc:
+          self.current_scope = nil
+        end
+
+        protected
+
+        # Use this macro in your model to set a default scope for all operations on
+        # the model.
+        #
+        #   class Article < ActiveRecord::Base
+        #     default_scope where(:published => true)
+        #   end
+        #
+        #   Article.all # => SELECT * FROM articles WHERE published = true
+        #
+        # The <tt>default_scope</tt> is also applied while creating/building a record. It is not
+        # applied while updating a record.
+        #
+        #   Article.new.published    # => true
+        #   Article.create.published # => true
+        #
+        # You can also use <tt>default_scope</tt> with a block, in order to have it lazily evaluated:
+        #
+        #   class Article < ActiveRecord::Base
+        #     default_scope { where(:published_at => Time.now - 1.week) }
+        #   end
+        #
+        # (You can also pass any object which responds to <tt>call</tt> to the <tt>default_scope</tt>
+        # macro, and it will be called when building the default scope.)
+        #
+        # If you use multiple <tt>default_scope</tt> declarations in your model then they will
+        # be merged together:
+        #
+        #   class Article < ActiveRecord::Base
+        #     default_scope where(:published => true)
+        #     default_scope where(:rating => 'G')
+        #   end
+        #
+        #   Article.all # => SELECT * FROM articles WHERE published = true AND rating = 'G'
+        #
+        # This is also the case with inheritance and module includes where the parent or module
+        # defines a <tt>default_scope</tt> and the child or including class defines a second one.
+        #
+        # If you need to do more complex things with a default scope, you can alternatively
+        # define it as a class method:
+        #
+        #   class Article < ActiveRecord::Base
+        #     def self.default_scope
+        #       # Should return a scope, you can call 'super' here etc.
+        #     end
+        #   end
+        def default_scope(scope = {})
+          scope = Proc.new if block_given?
+          self.default_scopes = default_scopes + [scope]
+        end
+
+        def build_default_scope #:nodoc:
+          if method(:default_scope).owner != ActiveRecord::Scoping::Default::ClassMethods
+            evaluate_default_scope { default_scope }
+          elsif default_scopes.any?
+            evaluate_default_scope do
+              default_scopes.inject(relation) do |default_scope, scope|
+                if scope.is_a?(Hash)
+                  default_scope.apply_finder_options(scope)
+                elsif !scope.is_a?(Relation) && scope.respond_to?(:call)
+                  default_scope.merge(scope.call)
+                else
+                  default_scope.merge(scope)
+                end
+              end
+            end
+          end
+        end
+
+        def ignore_default_scope? #:nodoc:
+          Thread.current["#{self}_ignore_default_scope"]
+        end
+
+        def ignore_default_scope=(ignore) #:nodoc:
+          Thread.current["#{self}_ignore_default_scope"] = ignore
+        end
+
+        # The ignore_default_scope flag is used to prevent an infinite recursion situation where
+        # a default scope references a scope which has a default scope which references a scope...
+        def evaluate_default_scope
+          return if ignore_default_scope?
+
+          begin
+            self.ignore_default_scope = true
+            yield
+          ensure
+            self.ignore_default_scope = false
+          end
+        end
+
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/scoping/named.rb b/activerecord/lib/active_record/scoping/named.rb
new file mode 100644
index 0000000000..f7512bbf5f
--- /dev/null
+++ b/activerecord/lib/active_record/scoping/named.rb
@@ -0,0 +1,202 @@
+require 'active_support/core_ext/array'
+require 'active_support/core_ext/hash/except'
+require 'active_support/core_ext/kernel/singleton_class'
+require 'active_support/core_ext/object/blank'
+require 'active_support/core_ext/class/attribute'
+
+module ActiveRecord
+  # = Active Record Named \Scopes
+  module Scoping
+    module Named
+      extend ActiveSupport::Concern
+
+      module ClassMethods
+        # Returns an anonymous \scope.
+        #
+        #   posts = Post.scoped
+        #   posts.size # Fires "select count(*) from  posts" and returns the count
+        #   posts.each {|p| puts p.name } # Fires "select * from posts" and loads post objects
+        #
+        #   fruits = Fruit.scoped
+        #   fruits = fruits.where(:color => 'red') if options[:red_only]
+        #   fruits = fruits.limit(10) if limited?
+        #
+        # Anonymous \scopes tend to be useful when procedurally generating complex
+        # queries, where passing intermediate values (\scopes) around as first-class
+        # objects is convenient.
+        #
+        # You can define a \scope that applies to all finders using
+        # ActiveRecord::Base.default_scope.
+        def scoped(options = nil)
+          if options
+            scoped.apply_finder_options(options)
+          else
+            if current_scope
+              current_scope.clone
+            else
+              scope = relation.clone
+              scope.default_scoped = true
+              scope
+            end
+          end
+        end
+
+        ##
+        # Collects attributes from scopes that should be applied when creating
+        # an AR instance for the particular class this is called on.
+        def scope_attributes # :nodoc:
+          if current_scope
+            current_scope.scope_for_create
+          else
+            scope = relation.clone
+            scope.default_scoped = true
+            scope.scope_for_create
+          end
+        end
+
+        ##
+        # Are there default attributes associated with this scope?
+        def scope_attributes? # :nodoc:
+          current_scope || default_scopes.any?
+        end
+
+        # Adds a class method for retrieving and querying objects. A \scope represents a narrowing of a database query,
+        # such as <tt>where(:color => :red).select('shirts.*').includes(:washing_instructions)</tt>.
+        #
+        #   class Shirt < ActiveRecord::Base
+        #     scope :red, where(:color => 'red')
+        #     scope :dry_clean_only, joins(:washing_instructions).where('washing_instructions.dry_clean_only = ?', true)
+        #   end
+        #
+        # The above calls to <tt>scope</tt> define class methods Shirt.red and Shirt.dry_clean_only. Shirt.red,
+        # in effect, represents the query <tt>Shirt.where(:color => 'red')</tt>.
+        #
+        # Note that this is simply 'syntactic sugar' for defining an actual class method:
+        #
+        #   class Shirt < ActiveRecord::Base
+        #     def self.red
+        #       where(:color => 'red')
+        #     end
+        #   end
+        #
+        # Unlike <tt>Shirt.find(...)</tt>, however, the object returned by Shirt.red 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.first</tt>, <tt>Shirt.red.count</tt>, <tt>Shirt.red.where(:size => 'small')</tt>.
+        # Also, just as with the association objects, named \scopes act 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 was 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::Base descendant 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
+        #     scope :colored, lambda { |color| where(:color => color) }
+        #   end
+        #
+        # In this example, <tt>Shirt.colored('puce')</tt> finds all puce shirts.
+        #
+        # On Ruby 1.9 you can use the 'stabby lambda' syntax:
+        #
+        #   scope :colored, ->(color) { where(:color => color) }
+        #
+        # Note that scopes defined with \scope will be evaluated when they are defined, rather than
+        # when they are used. For example, the following would be incorrect:
+        #
+        #   class Post < ActiveRecord::Base
+        #     scope :recent, where('published_at >= ?', Time.now - 1.week)
+        #   end
+        #
+        # The example above would be 'frozen' to the <tt>Time.now</tt> value when the <tt>Post</tt>
+        # class was defined, and so the resultant SQL query would always be the same. The correct
+        # way to do this would be via a lambda, which will re-evaluate the scope each time
+        # it is called:
+        #
+        #   class Post < ActiveRecord::Base
+        #     scope :recent, lambda { where('published_at >= ?', Time.now - 1.week) }
+        #   end
+        #
+        # Named \scopes can also have extensions, just as with <tt>has_many</tt> declarations:
+        #
+        #   class Shirt < ActiveRecord::Base
+        #     scope :red, where(:color => 'red') do
+        #       def dom_id
+        #         'red_shirts'
+        #       end
+        #     end
+        #   end
+        #
+        # Scopes can also be used while creating/building a record.
+        #
+        #   class Article < ActiveRecord::Base
+        #     scope :published, where(:published => true)
+        #   end
+        #
+        #   Article.published.new.published    # => true
+        #   Article.published.create.published # => true
+        #
+        # Class methods on your model are automatically available
+        # on scopes. Assuming the following setup:
+        #
+        #   class Article < ActiveRecord::Base
+        #     scope :published, where(:published => true)
+        #     scope :featured, where(:featured => true)
+        #
+        #     def self.latest_article
+        #       order('published_at desc').first
+        #     end
+        #
+        #     def self.titles
+        #       map(&:title)
+        #     end
+        #
+        #   end
+        #
+        # We are able to call the methods like this:
+        #
+        #   Article.published.featured.latest_article
+        #   Article.featured.titles
+
+        def scope(name, scope_options = {})
+          name = name.to_sym
+          valid_scope_name?(name)
+          extension = Module.new(&Proc.new) if block_given?
+
+          scope_proc = lambda do |*args|
+            options = scope_options.respond_to?(:call) ? scope_options.call(*args) : scope_options
+            options = scoped.apply_finder_options(options) if options.is_a?(Hash)
+
+            relation = scoped.merge(options)
+
+            extension ? relation.extending(extension) : relation
+          end
+
+          singleton_class.send(:redefine_method, name, &scope_proc)
+        end
+
+      protected
+
+        def valid_scope_name?(name)
+          if respond_to?(name, true)
+            logger.warn "Creating scope :#{name}. " \
+                        "Overwriting existing method #{self.name}.#{name}."
+          end
+        end
+      end
+    end
+  end
+end