has_many (ActiveRecord::Associations::ClassMethods)

    # File lib/active_record/associations.rb, line 708
          def has_many(association_id, options = {}, &extension)
            reflection = create_has_many_reflection(association_id, options, &extension)

            configure_dependency_for_has_many(reflection)

            add_multiple_associated_save_callbacks(reflection.name)
            add_association_callbacks(reflection.name, reflection.options)

            if options[:through]
              collection_accessor_methods(reflection, HasManyThroughAssociation)
            else
              collection_accessor_methods(reflection, HasManyAssociation)
            end
          end