Extract common dirty tracking methods in AMo

3 files changed, 122 insertions, 114 deletions

diff --git a/activemodel/lib/active_model.rb b/activemodel/lib/active_model.rb
index 9bb4cf8b54..b24a929ff5 100644
--- a/activemodel/lib/active_model.rb
+++ b/activemodel/lib/active_model.rb
@@ -29,6 +29,7 @@ module ActiveModel
   autoload :AttributeMethods, 'active_model/attribute_methods'
   autoload :Conversion, 'active_model/conversion'
   autoload :DeprecatedErrorMethods, 'active_model/deprecated_error_methods'
+  autoload :Dirty, 'active_model/dirty'
   autoload :Errors, 'active_model/errors'
   autoload :Name, 'active_model/naming'
   autoload :Naming, 'active_model/naming'
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
new file mode 100644
index 0000000000..624c3647ca
--- /dev/null
+++ b/activemodel/lib/active_model/dirty.rb
@@ -0,0 +1,112 @@
+module ActiveModel
+  # Track unsaved attribute changes.
+  #
+  # A newly instantiated object is unchanged:
+  #   person = Person.find_by_name('Uncle Bob')
+  #   person.changed?       # => false
+  #
+  # Change the name:
+  #   person.name = 'Bob'
+  #   person.changed?       # => true
+  #   person.name_changed?  # => true
+  #   person.name_was       # => 'Uncle Bob'
+  #   person.name_change    # => ['Uncle Bob', 'Bob']
+  #   person.name = 'Bill'
+  #   person.name_change    # => ['Uncle Bob', 'Bill']
+  #
+  # Save the changes:
+  #   person.save
+  #   person.changed?       # => false
+  #   person.name_changed?  # => false
+  #
+  # Assigning the same value leaves the attribute unchanged:
+  #   person.name = 'Bill'
+  #   person.name_changed?  # => false
+  #   person.name_change    # => nil
+  #
+  # Which attributes have changed?
+  #   person.name = 'Bob'
+  #   person.changed        # => ['name']
+  #   person.changes        # => { 'name' => ['Bill', 'Bob'] }
+  #
+  # Resetting an attribute returns it to its original state:
+  #   person.reset_name!    # => 'Bill'
+  #   person.changed?       # => false
+  #   person.name_changed?  # => false
+  #   person.name           # => 'Bill'
+  #
+  # Before modifying an attribute in-place:
+  #   person.name_will_change!
+  #   person.name << 'y'
+  #   person.name_change    # => ['Bill', 'Billy']
+  module Dirty
+    extend ActiveSupport::Concern
+    include ActiveModel::AttributeMethods
+
+    included do
+      attribute_method_suffix '_changed?', '_change', '_will_change!', '_was'
+      attribute_method_affix :prefix => 'reset_', :suffix => '!'
+    end
+
+    # Do any attributes have unsaved changes?
+    #   person.changed? # => false
+    #   person.name = 'bob'
+    #   person.changed? # => true
+    def changed?
+      !changed_attributes.empty?
+    end
+
+    # List of attributes with unsaved changes.
+    #   person.changed # => []
+    #   person.name = 'bob'
+    #   person.changed # => ['name']
+    def changed
+      changed_attributes.keys
+    end
+
+    # Map of changed attrs => [original value, new value].
+    #   person.changes # => {}
+    #   person.name = 'bob'
+    #   person.changes # => { 'name' => ['bill', 'bob'] }
+    def changes
+      changed.inject({}) { |h, attr| h[attr] = attribute_change(attr); h }
+    end
+
+    private
+      # Map of change <tt>attr => original value</tt>.
+      def changed_attributes
+        @changed_attributes ||= {}
+      end
+
+      # Handle <tt>*_changed?</tt> for +method_missing+.
+      def attribute_changed?(attr)
+        changed_attributes.include?(attr)
+      end
+
+      # Handle <tt>*_change</tt> for +method_missing+.
+      def attribute_change(attr)
+        [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
+      end
+
+      # Handle <tt>*_was</tt> for +method_missing+.
+      def attribute_was(attr)
+        attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
+      end
+
+      # Handle <tt>*_will_change!</tt> for +method_missing+.
+      def attribute_will_change!(attr)
+        begin
+          value = __send__(attr)
+          value = value.duplicable? ? value.clone : value
+        rescue TypeError, NoMethodError
+        end
+
+        changed_attributes[attr] = value
+      end
+
+      # Handle <tt>reset_*!</tt> for +method_missing+.
+      def reset_attribute!(attr)
+        __send__("#{attr}=", changed_attributes[attr]) if attribute_changed?(attr)
+      end
+  end
+end
diff --git a/activerecord/lib/active_record/attribute_methods/dirty.rb b/activerecord/lib/active_record/attribute_methods/dirty.rb
index 37a46f7d88..b6c4df2a49 100644
--- a/activerecord/lib/active_record/attribute_methods/dirty.rb
+++ b/activerecord/lib/active_record/attribute_methods/dirty.rb
@@ -1,92 +1,21 @@
+require 'active_support/core_ext/object/tap'
+
 module ActiveRecord
   module AttributeMethods
-    # Track unsaved attribute changes.
-    #
-    # A newly instantiated object is unchanged:
-    #   person = Person.find_by_name('Uncle Bob')
-    #   person.changed?       # => false
-    #
-    # Change the name:
-    #   person.name = 'Bob'
-    #   person.changed?       # => true
-    #   person.name_changed?  # => true
-    #   person.name_was       # => 'Uncle Bob'
-    #   person.name_change    # => ['Uncle Bob', 'Bob']
-    #   person.name = 'Bill'
-    #   person.name_change    # => ['Uncle Bob', 'Bill']
-    #
-    # Save the changes:
-    #   person.save
-    #   person.changed?       # => false
-    #   person.name_changed?  # => false
-    #
-    # Assigning the same value leaves the attribute unchanged:
-    #   person.name = 'Bill'
-    #   person.name_changed?  # => false
-    #   person.name_change    # => nil
-    #
-    # Which attributes have changed?
-    #   person.name = 'Bob'
-    #   person.changed        # => ['name']
-    #   person.changes        # => { 'name' => ['Bill', 'Bob'] }
-    #
-    # Resetting an attribute returns it to its original state:
-    #   person.reset_name!    # => 'Bill'
-    #   person.changed?       # => false
-    #   person.name_changed?  # => false
-    #   person.name           # => 'Bill'
-    #
-    # Before modifying an attribute in-place:
-    #   person.name_will_change!
-    #   person.name << 'y'
-    #   person.name_change    # => ['Bill', 'Billy']
     module Dirty
       extend ActiveSupport::Concern
-
-      DIRTY_AFFIXES = [
-        { :suffix => '_changed?' },
-        { :suffix => '_change' },
-        { :suffix => '_will_change!' },
-        { :suffix => '_was' },
-        { :prefix => 'reset_', :suffix => '!' }
-      ]
+      include ActiveModel::Dirty
 
       included do
-        attribute_method_affix *DIRTY_AFFIXES
-
-        alias_method_chain :save,            :dirty
-        alias_method_chain :save!,           :dirty
-        alias_method_chain :update,          :dirty
-        alias_method_chain :reload,          :dirty
+        alias_method_chain :save,   :dirty
+        alias_method_chain :save!,  :dirty
+        alias_method_chain :update, :dirty
+        alias_method_chain :reload, :dirty
 
         superclass_delegating_accessor :partial_updates
         self.partial_updates = true
       end
 
-      # Do any attributes have unsaved changes?
-      #   person.changed? # => false
-      #   person.name = 'bob'
-      #   person.changed? # => true
-      def changed?
-        !changed_attributes.empty?
-      end
-
-      # List of attributes with unsaved changes.
-      #   person.changed # => []
-      #   person.name = 'bob'
-      #   person.changed # => ['name']
-      def changed
-        changed_attributes.keys
-      end
-
-      # Map of changed attrs => [original value, new value].
-      #   person.changes # => {}
-      #   person.name = 'bob'
-      #   person.changes # => { 'name' => ['bill', 'bob'] }
-      def changes
-        changed.inject({}) { |h, attr| h[attr] = attribute_change(attr); h }
-      end
-
       # Attempts to +save+ the record and clears changed attributes if successful.
       def save_with_dirty(*args) #:nodoc:
         if status = save_without_dirty(*args)
@@ -97,49 +26,15 @@ module ActiveRecord
 
       # Attempts to <tt>save!</tt> the record and clears changed attributes if successful.
       def save_with_dirty!(*args) #:nodoc:
-        status = save_without_dirty!(*args)
-        changed_attributes.clear
-        status
+        save_without_dirty!(*args).tap { changed_attributes.clear }
       end
 
       # <tt>reload</tt> the record and clears changed attributes.
       def reload_with_dirty(*args) #:nodoc:
-        record = reload_without_dirty(*args)
-        changed_attributes.clear
-        record
+        reload_without_dirty(*args).tap { changed_attributes.clear }
       end
 
       private
-        # Map of change <tt>attr => original value</tt>.
-        def changed_attributes
-          @changed_attributes ||= {}
-        end
-
-        # Handle <tt>*_changed?</tt> for +method_missing+.
-        def attribute_changed?(attr)
-          changed_attributes.include?(attr)
-        end
-
-        # Handle <tt>*_change</tt> for +method_missing+.
-        def attribute_change(attr)
-          [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
-        end
-
-        # Handle <tt>*_was</tt> for +method_missing+.
-        def attribute_was(attr)
-          attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
-        end
-
-        # Handle <tt>reset_*!</tt> for +method_missing+.
-        def reset_attribute!(attr)
-          self[attr] = changed_attributes[attr] if attribute_changed?(attr)
-        end
-
-        # Handle <tt>*_will_change!</tt> for +method_missing+.
-        def attribute_will_change!(attr)
-          changed_attributes[attr] = clone_attribute_value(:read_attribute, attr)
-        end
-
         # Wrap write_attribute to remember original attribute value.
         def write_attribute(attr, value)
           attr = attr.to_s