Improve comments; move caching concern to caching.rb

lib/active_model/serializer.rb

@@ -108,8 +108,8 @@ module ActiveModel
       @serialization_adapter_instance ||= ActiveModelSerializers::Adapter::Attributes
     end
 
-    # Configuration options may also be set in
+    # Preferred interface is ActiveModelSerializers.config
-    # Serializers and Adapters
+    # BEGIN DEFAULT CONFIGURATION
     config.collection_serializer = ActiveModel::Serializer::CollectionSerializer
     config.serializer_lookup_enabled = true
 
@@ -159,6 +159,7 @@ module ActiveModel
     config.serializer_lookup_chain = ActiveModelSerializers::LookupChain::DEFAULT.dup
 
     config.schema_path = 'test/support/schemas'
+    # END DEFAULT CONFIGURATION
 
     with_options instance_writer: false, instance_reader: false do |serializer|
       serializer.class_attribute :_attributes_data # @api private
@@ -180,12 +181,14 @@ module ActiveModel
       base._links = _links.dup
     end
 
-    # keys of attributes
+    # @return [Array<Symbol>] Key names of declared attributes
     # @see Serializer::attribute
     def self._attributes
       _attributes_data.keys
     end
 
+    # BEGIN SERIALIZER MACROS
+
     # @example
     #   class AdminAuthorSerializer < ActiveModel::Serializer
     #     attributes :id, :name, :recent_edits
@@ -214,18 +217,6 @@ module ActiveModel
       _attributes_data[key] = Attribute.new(attr, options, block)
     end
 
-    # @api private
-    # maps attribute value to explicit key name
-    # @see Serializer::attribute
-    # @see ActiveModel::Serializer::Caching#fragmented_attributes
-    def self._attributes_keys
-      _attributes_data
-        .each_with_object({}) do |(key, attr), hash|
-        next if key == attr.name
-        hash[attr.name] = { key: key }
-      end
-    end
-
     # @param [Symbol] name of the association
     # @param [Hash<Symbol => any>] options for the reflection
     # @return [void]
@@ -302,6 +293,8 @@ module ActiveModel
       self._type = type && type.to_s
     end
 
+    # END SERIALIZER MACROS
+
     attr_accessor :object, :root, :scope
 
     # `scope_name` is set as :current_user by default in the controller.

lib/active_model/serializer/concerns/caching.rb

@@ -68,6 +68,18 @@ module ActiveModel
           _cache_options && _cache_options[:skip_digest]
         end
 
+        # @api private
+        # maps attribute value to explicit key name
+        # @see Serializer::attribute
+        # @see Serializer::fragmented_attributes
+        def _attributes_keys
+          _attributes_data
+            .each_with_object({}) do |(key, attr), hash|
+            next if key == attr.name
+            hash[attr.name] = { key: key }
+          end
+        end
+
         def fragmented_attributes
           cached = _cache_only ? _cache_only : _attributes - _cache_except
           cached = cached.map! { |field| _attributes_keys.fetch(field, field) }