Refactor method definition to private methods

lib/mobility/plugins/active_record/dirty.rb

@@ -30,7 +30,30 @@ class MethodsBuilder < ActiveModel::Dirty::MethodsBuilder
           def initialize(*attribute_names)
             super
             @attribute_names = attribute_names
+            define_method_overrides
+            define_attribute_methods if ::ActiveRecord::VERSION::STRING >= '5.1'
+          end
 
+          # Overrides +ActiveRecord::AttributeMethods::ClassMethods#has_attribute+ to treat fallthrough attribute methods
+          # just like "real" attribute methods.
+          #
+          # @note Patching +has_attribute?+ is necessary as of AR 5.1 due to this commit[https://github.com/rails/rails/commit/4fed08fa787a316fa51f14baca9eae11913f5050].
+          #   (I have voiced my opposition to this change here[https://github.com/rails/rails/pull/27963#issuecomment-310092787]).
+          # @param [Attributes] attributes
+          def included(model_class)
+            names = @attribute_names
+            method_name_regex = /\A(#{names.join('|'.freeze)})_([a-z]{2}(_[a-z]{2})?)(=?|\??)\z/.freeze
+            has_attribute = Module.new do
+              define_method :has_attribute? do |attr_name|
+                super(attr_name) || !!method_name_regex.match(attr_name)
+              end
+            end
+            model_class.extend has_attribute
+          end
+
+          private
+
+          def define_method_overrides
             changes_applied_method = ::ActiveRecord::VERSION::STRING < '5.1' ? :changes_applied : :changes_internally_applied
             define_method changes_applied_method do
               @previously_changed = changes
@@ -45,47 +68,31 @@ def initialize(*attribute_names)
             define_method :previous_changes do
               (@previously_changed ||= ActiveSupport::HashWithIndifferentAccess.new).merge(super())
             end
+          end
 
-            if ::ActiveRecord::VERSION::STRING >= '5.1'
-              define_method :saved_changes do
-                (@previously_changed ||= ActiveSupport::HashWithIndifferentAccess.new).merge(super())
-              end
-
-              attribute_names.each do |name|
-                define_method :"saved_change_to_#{name}?" do
-                  previous_changes.include?(Mobility.normalize_locale_accessor(name))
-                end
-
-                define_method :"saved_change_to_#{name}" do
-                  previous_changes[Mobility.normalize_locale_accessor(name)]
-                end
+          # For AR >= 5.1 only
+          def define_attribute_methods
+            define_method :saved_changes do
+              (@previously_changed ||= ActiveSupport::HashWithIndifferentAccess.new).merge(super())
+            end
 
-                define_method :"#{name}_before_last_save" do
-                  previous_changes[Mobility.normalize_locale_accessor(name)].first
-                end
+            @attribute_names.each do |name|
+              define_method :"saved_change_to_#{name}?" do
+                previous_changes.include?(Mobility.normalize_locale_accessor(name))
+              end
 
-                alias_method :"will_save_change_to_#{name}?", :"#{name}_changed?"
-                alias_method :"#{name}_change_to_be_saved", :"#{name}_change"
-                alias_method :"#{name}_in_database", :"#{name}_was"
+              define_method :"saved_change_to_#{name}" do
+                previous_changes[Mobility.normalize_locale_accessor(name)]
               end
-            end
-          end
 
-          # Overrides +ActiveRecord::AttributeMethods::ClassMethods#has_attribute+ to treat fallthrough attribute methods
-          # just like "real" attribute methods.
-          #
-          # @note Patching +has_attribute?+ is necessary as of AR 5.1 due to this commit[https://github.com/rails/rails/commit/4fed08fa787a316fa51f14baca9eae11913f5050].
-          #   (I have voiced my opposition to this change here[https://github.com/rails/rails/pull/27963#issuecomment-310092787]).
-          # @param [Attributes] attributes
-          def included(model_class)
-            names = @attribute_names
-            method_name_regex = /\A(#{names.join('|'.freeze)})_([a-z]{2}(_[a-z]{2})?)(=?|\??)\z/.freeze
-            has_attribute = Module.new do
-              define_method :has_attribute? do |attr_name|
-                super(attr_name) || !!method_name_regex.match(attr_name)
+              define_method :"#{name}_before_last_save" do
+                previous_changes[Mobility.normalize_locale_accessor(name)].first
               end
+
+              alias_method :"will_save_change_to_#{name}?", :"#{name}_changed?"
+              alias_method :"#{name}_change_to_be_saved", :"#{name}_change"
+              alias_method :"#{name}_in_database", :"#{name}_was"
             end
-            model_class.extend has_attribute
           end
         end
       end