Use Object#singleton_class instead of #metaclass. Prefer Ruby's choice.

6 files changed, 22 insertions, 19 deletions

diff --git a/activesupport/lib/active_support/callbacks.rb b/activesupport/lib/active_support/callbacks.rb
index 6727eda811..b230bb8a40 100644
--- a/activesupport/lib/active_support/callbacks.rb
+++ b/activesupport/lib/active_support/callbacks.rb
@@ -1,7 +1,7 @@
 require 'active_support/core_ext/array/wrap'
 require 'active_support/core_ext/class/inheritable_attributes'
 require 'active_support/core_ext/kernel/reporting'
-require 'active_support/core_ext/object/metaclass'
+require 'active_support/core_ext/object/singleton_class'
 
 module ActiveSupport
   # Callbacks are hooks into the lifecycle of an object that allow you to trigger logic
@@ -312,7 +312,7 @@ module ActiveSupport
 
       def _normalize_legacy_filter(kind, filter)
         if !filter.respond_to?(kind) && filter.respond_to?(:filter)
-          filter.metaclass.class_eval(
+          filter.singleton_class.class_eval(
             "def #{kind}(context, &block) filter(context, &block) end",
             __FILE__, __LINE__ - 1)
         elsif filter.respond_to?(:before) && filter.respond_to?(:after) && kind == :around
diff --git a/activesupport/lib/active_support/core_ext/class/attribute.rb b/activesupport/lib/active_support/core_ext/class/attribute.rb
index d74219cb93..1bd39a9349 100644
--- a/activesupport/lib/active_support/core_ext/class/attribute.rb
+++ b/activesupport/lib/active_support/core_ext/class/attribute.rb
@@ -1,4 +1,4 @@
-require 'active_support/core_ext/object/metaclass'
+require 'active_support/core_ext/object/singleton_class'
 require 'active_support/core_ext/module/delegation'
 
 class Class
@@ -25,11 +25,12 @@ class Class
   #
   #   Subclass.setting?           # => false
   def class_attribute(*attrs)
+    s = singleton_class
     attrs.each do |attr|
-      metaclass.send(:define_method, attr) { }
-      metaclass.send(:define_method, "#{attr}?") { !!send(attr) }
-      metaclass.send(:define_method, "#{attr}=") do |value|
-        metaclass.send(:define_method, attr) { value }
+      s.send(:define_method, attr) { }
+      s.send(:define_method, "#{attr}?") { !!send(attr) }
+      s.send(:define_method, "#{attr}=") do |value|
+        singleton_class.send(:define_method, attr) { value }
       end
     end
   end
diff --git a/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb b/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
index 19382abb76..b5785bdcd3 100644
--- a/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
+++ b/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
@@ -1,6 +1,6 @@
 require 'active_support/core_ext/object/blank'
 require 'active_support/core_ext/array/extract_options'
-require 'active_support/core_ext/object/metaclass'
+require 'active_support/core_ext/object/singleton_class'
 
 class Class
   def superclass_delegating_accessor(name, options = {})
@@ -11,9 +11,9 @@ class Class
     # Generate the public methods name, name=, and name?
     # These methods dispatch to the private _name, and _name= methods, making them
     # overridable
-    metaclass.send(:define_method, name) { send("_#{name}") }
-    metaclass.send(:define_method, "#{name}?") { !!send("_#{name}") }
-    metaclass.send(:define_method, "#{name}=") { |value| send("_#{name}=", value) }
+    singleton_class.send(:define_method, name) { send("_#{name}") }
+    singleton_class.send(:define_method, "#{name}?") { !!send("_#{name}") }
+    singleton_class.send(:define_method, "#{name}=") { |value| send("_#{name}=", value) }
 
     # If an instance_reader is needed, generate methods for name and name= on the
     # class itself, so instances will be able to see them
@@ -27,12 +27,12 @@ private
   # inheritance behavior, without having to store the object in an instance
   # variable and look up the superclass chain manually.
   def _stash_object_in_method(object, method, instance_reader = true)
-    metaclass.send(:define_method, method) { object }
+    singleton_class.send(:define_method, method) { object }
     define_method(method) { object } if instance_reader
   end
 
   def _superclass_delegating_accessor(name, options = {})
-    metaclass.send(:define_method, "#{name}=") do |value|
+    singleton_class.send(:define_method, "#{name}=") do |value|
       _stash_object_in_method(value, name, options[:instance_reader] != false)
     end
     self.send("#{name}=", nil)
diff --git a/activesupport/lib/active_support/core_ext/object.rb b/activesupport/lib/active_support/core_ext/object.rb
index db2dac1472..9dc6ca66a4 100644
--- a/activesupport/lib/active_support/core_ext/object.rb
+++ b/activesupport/lib/active_support/core_ext/object.rb
@@ -6,6 +6,7 @@ require 'active_support/core_ext/object/try'
 require 'active_support/core_ext/object/conversions'
 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'
 require 'active_support/core_ext/object/extending'
 
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/lib/active_support/memoizable.rb b/activesupport/lib/active_support/memoizable.rb
index f810f53029..ca1cfedae3 100644
--- a/activesupport/lib/active_support/memoizable.rb
+++ b/activesupport/lib/active_support/memoizable.rb
@@ -1,4 +1,4 @@
-require 'active_support/core_ext/object/metaclass'
+require 'active_support/core_ext/object/singleton_class'
 require 'active_support/core_ext/module/aliasing'
 
 module ActiveSupport