# File lib/active_record/aggregations.rb, line 128 def composed_of(part_id, options = {}) options.assert_valid_keys(:class_name, :mapping) name = part_id.id2name class_name = options[:class_name] || name_to_class_name(name) mapping = options[:mapping] || [ name, name ] reader_method(name, class_name, mapping) writer_method(name, class_name, mapping) end