Get rid of the underscore versions of attribute methods!

This makes me happy!

activerecord/lib/active_record.rb

@@ -93,6 +93,7 @@ module AttributeMethods
       autoload :TimeZoneConversion
       autoload :Write
       autoload :Serialization
+      autoload :DeprecatedUnderscoreRead
     end
   end
 

activerecord/lib/active_record/attribute_methods/deprecated_underscore_read.rb

+require 'active_support/concern'
+require 'active_support/deprecation'
+
+module ActiveRecord
+  module AttributeMethods
+    module DeprecatedUnderscoreRead
+      extend ActiveSupport::Concern
+
+      included do
+        attribute_method_prefix "_"
+      end
+
+      module ClassMethods
+        protected
+
+        def define_method__attribute(attr_name)
+          # Do nothing, let it hit method missing instead.
+        end
+      end
+
+      protected
+
+      def _attribute(attr_name)
+        ActiveSupport::Deprecation.warn(
+          "You have called '_#{attr_name}'. This is deprecated. Please use " \
+          "either '#{attr_name}' or read_attribute('#{attr_name}')."
+        )
+        read_attribute(attr_name)
+      end
+    end
+  end
+end

activerecord/lib/active_record/attribute_methods/primary_key.rb

@@ -13,7 +13,6 @@ def to_key
       def id
         read_attribute(self.class.primary_key)
       end
-      alias _id id
 
       # Sets the primary key value
       def id=(value)
@@ -27,7 +26,7 @@ def id?
 
       module ClassMethods
         def dangerous_attribute_method?(method_name)
-          super && !['id', 'id=', 'id?', '_id'].include?(method_name)
+          super && !['id', 'id=', 'id?'].include?(method_name)
         end
 
         # Defines the primary key field -- can be overridden in subclasses. Overwriting will negate any effect of the

activerecord/lib/active_record/attribute_methods/read.rb

@@ -61,8 +61,6 @@ def #{attr_name}
                 def self.cast_#{attr_name}(v)
                   #{cast_code}
                 end
-
-                alias _#{attr_name} #{attr_name}
               STR
             else
               generated_attribute_methods.module_eval do
@@ -73,8 +71,6 @@ def self.cast_#{attr_name}(v)
                 singleton_class.send(:define_method, "cast_#{attr_name}") do |v|
                   eval(cast_code)
                 end
-
-                alias_method("_#{attr_name}", attr_name)
               end
             end
           end

activerecord/lib/active_record/base.rb

@@ -2200,6 +2200,7 @@ def populate_with_current_scope_attributes
     include AttributeMethods::TimeZoneConversion
     include AttributeMethods::Dirty
     include AttributeMethods::Serialization
+    include AttributeMethods::DeprecatedUnderscoreRead
     include ActiveModel::MassAssignmentSecurity
     include Callbacks, ActiveModel::Observing, Timestamp
     include Associations, NamedScope

activerecord/test/cases/attribute_methods_test.rb

@@ -114,6 +114,11 @@ def test_respond_to?
     assert !topic.respond_to?(:nothingness)
   end
 
+  def test_deprecated_underscore_method
+    topic = Topic.find(1)
+    assert_equal topic.title, assert_deprecated { topic._title }
+  end
+
   def test_respond_to_with_custom_primary_key
     keyboard = Keyboard.create
     assert_not_nil keyboard.key_number