From 63a7ef0d745dac45829d63ed258b90ae0df7d593 Mon Sep 17 00:00:00 2001
From: Jeremy Kemper <jeremy@bitsweat.net>
Date: Thu, 25 Feb 2010 09:32:29 -0800
Subject: [PATCH] Use Object#singleton_class instead of #metaclass. Prefer
 Ruby's choice.

---
 activerecord/lib/active_record/dirty.rb            |  2 +-
 activesupport/CHANGELOG                            |  2 ++
 .../lib/active_support/core_ext/object.rb          |  1 +
 .../active_support/core_ext/object/metaclass.rb    | 11 ++++++-----
 .../test/core_ext/object_and_class_ext_test.rb     | 14 +++++++++++++-
 5 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/activerecord/lib/active_record/dirty.rb b/activerecord/lib/active_record/dirty.rb
index f18965169d..ef0f3b81c4 100644
--- a/activerecord/lib/active_record/dirty.rb
+++ b/activerecord/lib/active_record/dirty.rb
@@ -167,7 +167,7 @@ module ActiveRecord
 
     module ClassMethods
       def self.extended(base)
-        base.metaclass.alias_method_chain(:alias_attribute, :dirty)
+        base.singleton_class.alias_method_chain(:alias_attribute, :dirty)
       end
 
       def alias_attribute_with_dirty(new_name, old_name)
diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index 0e763ce079..440c6e7287 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *2.3.6 (pending)*
 
+* Use Object#singleton_class instead of #metaclass. Prefer Ruby's choice.  [Jeremy Kemper]
+
 * JSON backend for YAJL. Preferred if available.  #2666 [Brian Lopez]
 
 * Introduce String#html_safe for rails_xss plugin and forward-compatibility with Rails 3.  [Michael Koziarski, Santiago Pastorino, José Ignacio Costa]
diff --git a/activesupport/lib/active_support/core_ext/object.rb b/activesupport/lib/active_support/core_ext/object.rb
index f140be3c8d..65bc222b80 100644
--- a/activesupport/lib/active_support/core_ext/object.rb
+++ b/activesupport/lib/active_support/core_ext/object.rb
@@ -3,4 +3,5 @@ require 'active_support/core_ext/object/conversions'
 require 'active_support/core_ext/object/extending'
 require 'active_support/core_ext/object/instance_variables'
 require 'active_support/core_ext/object/metaclass'
+require 'active_support/core_ext/object/singleton_class'
 require 'active_support/core_ext/object/misc'
diff --git a/activesupport/lib/active_support/core_ext/object/metaclass.rb b/activesupport/lib/active_support/core_ext/object/metaclass.rb
index 93fb0ad594..4b36a243c9 100644
--- a/activesupport/lib/active_support/core_ext/object/metaclass.rb
+++ b/activesupport/lib/active_support/core_ext/object/metaclass.rb
@@ -1,13 +1,14 @@
+require 'active_support/deprecation'
+
 class Object
-  # Get object's meta (ghost, eigenclass, singleton) class
+  # Get object's meta (ghost, eigenclass, singleton) class.
+  #
+  # Deprecated in favor of Object#singleton_class.
   def metaclass
     class << self
       self
     end
   end
 
-  # If class_eval is called on an object, add those methods to its metaclass
-  def class_eval(*args, &block)
-    metaclass.class_eval(*args, &block)
-  end
+  deprecate :metaclass => :singleton_class
 end
diff --git a/activesupport/test/core_ext/object_and_class_ext_test.rb b/activesupport/test/core_ext/object_and_class_ext_test.rb
index b6515e05a0..fcaaeb4ca4 100644
--- a/activesupport/test/core_ext/object_and_class_ext_test.rb
+++ b/activesupport/test/core_ext/object_and_class_ext_test.rb
@@ -107,7 +107,7 @@ class ClassExtTest < Test::Unit::TestCase
   end
 end
 
-class ObjectTests < Test::Unit::TestCase
+class ObjectTests < ActiveSupport::TestCase
   def test_suppress_re_raises
     assert_raise(LoadError) { suppress(ArgumentError) {raise LoadError} }
   end
@@ -176,6 +176,18 @@ class ObjectTests < Test::Unit::TestCase
     end
     assert_equal "bar", string.foo
   end
+
+  def test_singleton_class
+    o = Object.new
+    assert_equal class << o; self end, o.singleton_class
+  end
+
+  def test_metaclass_deprecated
+    o = Object.new
+    assert_deprecated /use singleton_class instead/ do
+      assert_equal o.singleton_class, o.metaclass
+    end
+   end
 end
 
 class ObjectInstanceVariableTest < Test::Unit::TestCase