attribute

# File activesupport/lib/active_support/current_attributes.rb, line 114
      def attribute(*names, default: NOT_SET)
        invalid_attribute_names = names.map(&:to_sym) & INVALID_ATTRIBUTE_NAMES
        if invalid_attribute_names.any?
          raise ArgumentError, "Restricted attribute names: #{invalid_attribute_names.join(", ")}"
        end

        Delegation.generate(singleton_class, names, to: :instance, nilable: false, signature: "")
        Delegation.generate(singleton_class, names.map { |n| "#{n}=" }, to: :instance, nilable: false, signature: "value")

        ActiveSupport::CodeGenerator.batch(generated_attribute_methods, __FILE__, __LINE__) do |owner|
          names.each do |name|
            owner.define_cached_method(name, namespace: :current_attributes) do |batch|
              batch <<
                "def #{name}" <<
                "attributes[:#{name}]" <<
                "end"
            end
            owner.define_cached_method("#{name}=", namespace: :current_attributes) do |batch|
              batch <<
                "def #{name}=(value)" <<
                "attributes[:#{name}] = value" <<
                "end"
            end
          end
        end

        self.defaults = defaults.merge(names.index_with { default })
      end