Extremely lightweight "Struct" that only defines attribute readers

value_object.rb

module ValueObject
  def self.new(*attrs)
    klass = Class.new(Object)

    klass.send(:attr_reader, *attrs)

    klass.send(:define_method, :initialize) do |*args|
      raise ArgumentError, "wrong number of arguments (#{args.size} for #{attrs.size})" unless args.size == attrs.size
      attrs.each_with_index do |attr, idx|
        instance_variable_set("@#{attr}", args[idx])
      end
    end

    klass
  end
end

Use case:

class Name < ValueObject.new(:name, :surname)
   def to_s
     [name,surname].compact.join(" ")
   end
end

n = Name.new("Guillermo", "Alvarez")
n.name    #=> "Guillermo"
n.surname #=> "Alvarez"
n.to_s    #=> "Guillermo Álvarez"