Refactoring .reflections public method.

Now the internal reflections will hold a reference to its public
representation, so when the outside world calls `Account.reflection` we
can build a list of public reflections.

activerecord/lib/active_record/associations.rb

@@ -1577,6 +1577,8 @@ module ActiveRecord
           scope   = nil
         end
 
+        habtm_reflection = ActiveRecord::Reflection::AssociationReflection.new(:has_and_belongs_to_many, name, scope, options, self)
+
         builder = Builder::HasAndBelongsToMany.new name, self, options
 
         join_model = builder.through_model
@@ -1590,6 +1592,7 @@ module ActiveRecord
 
         Builder::HasMany.define_callbacks self, middle_reflection
         Reflection.add_reflection self, middle_reflection.name, middle_reflection
+        middle_reflection.parent_reflection = [name.to_s, habtm_reflection]
 
         include Module.new {
           class_eval <<-RUBY, __FILE__, __LINE__ + 1
@@ -1610,9 +1613,7 @@ module ActiveRecord
         end
 
         has_many name, scope, hm_options, &extension
-
-        reflection = ActiveRecord::Reflection::AssociationReflection.new(:has_and_belongs_to_many, name, scope, options, self)
-        self.reflections = self.reflections.except(middle_reflection.name).merge!(name.to_s => reflection)
+        self._reflections[name.to_s].parent_reflection = [name.to_s, habtm_reflection]
       end
     end
   end

activerecord/lib/active_record/counter_cache.rb

@@ -166,7 +166,7 @@ module ActiveRecord
       end
 
       def each_counter_cached_associations
-        reflections.each do |name, reflection|
+        _reflections.each do |name, reflection|
           yield association(name) if reflection.belongs_to? && reflection.counter_cache_column
         end
       end

activerecord/lib/active_record/nested_attributes.rb

@@ -307,7 +307,6 @@ module ActiveRecord
         attr_names.each do |association_name|
           if reflection = _reflect_on_association(association_name)
             reflection.autosave = true
-            reflect_on_association(association_name).autosave = true
             add_autosave_association_callbacks(reflection)
 
             nested_attributes_options = self.nested_attributes_options.dup

activerecord/lib/active_record/reflection.rb

@@ -7,11 +7,8 @@ module ActiveRecord
 
     included do
       class_attribute :_reflections
-      # @api public
-      class_attribute :reflections
       class_attribute :aggregate_reflections
       self._reflections = {}
-      self.reflections = {}
       self.aggregate_reflections = {}
     end
 
@@ -28,7 +25,6 @@ module ActiveRecord
 
     def self.add_reflection(ar, name, reflection)
       ar._reflections = ar._reflections.merge(name.to_s => reflection)
-      ar.reflections = ar.reflections.merge(name.to_s => reflection)
     end
 
     def self.add_aggregate_reflection(ar, name, reflection)
@@ -57,6 +53,24 @@ module ActiveRecord
         aggregate_reflections[aggregation.to_s]
       end
 
+      # Returns a Hash of name of the reflection as the key and a AssociationReflection as the value.
+      #
+      #   Account.reflections # => {balance: AggregateReflection}
+      #
+      # @api public
+      def reflections
+        ref = {}
+        _reflections.each do |name, reflection|
+          parent_name, parent_reflection = reflection.parent_reflection
+          if parent_name
+            ref[parent_name] = parent_reflection
+          else
+            ref[name] = reflection
+          end
+        end
+        ref
+      end
+
       # Returns an array of AssociationReflection objects for all the
       # associations in the class. If you only want to reflect on a certain
       # association type, pass in the symbol (<tt>:has_many</tt>, <tt>:has_one</tt>,
@@ -142,6 +156,10 @@ module ActiveRecord
       def autosave=(autosave)
         @automatic_inverse_of = false
         @options[:autosave] = autosave
+        _, parent_reflection = self.parent_reflection
+        if parent_reflection
+          parent_reflection.autosave = autosave
+        end
       end
 
       # Returns the class for the macro.
@@ -206,6 +224,7 @@ module ActiveRecord
       end
 
       attr_reader :type, :foreign_type
+      attr_accessor :parent_reflection # [:name, Reflection]
 
       def initialize(macro, name, scope, options, active_record)
         super