You have a method whose implementation steps are so common that they can safely be hidden away.

introduce_class_annotation.rb

module CustomInitializers
  def hash_initializer(*attribute_names)
    define_method(:initialize) do |*args|
      data = args.first
      attribute_names.each do |attr|
        instance_variable_set "@#{attr}", data[attr]
      end
    end

    self.class_eval do
      attr_reader *attribute_names
    end
  end
end