gistfile1.rb

module Constructor
  def constructor(*names)
    define_method(:initialize) do |*args|
      names.zip(args).each do |name, value|
        instance_variable_set("@#{name}", value)
      end
    end
  end
end

class Hi
  extend Constructor

  constructor :foo, :bar

  def do
    p @foo
    p @bar
  end
end

Hi.new('FOO', 'BAR').do