gistfile1.rb

class Object
  def self.attributes(*attrs)
    attrs.each do |attr|
      define_method attr do
        instance_variable_get "@#{attr}"
      end

      define_method "#{attr}=" do |value|
        instance_variable_set "@#{attr}", value
      end
    end
  end
end

Object.instance_eval do
  def setters(*attrs)
    attrs.each do |attr|
      class_eval <<-EOS
        def #{attr}=(value)
          @#{attr} = value
        end
      EOS
    end
  end

  def getters(*attrs)
    attrs.each do |attr|
      class_eval "def #{attr} ; @#{attr} ; end"
    end
  end
end

class Person
  attributes :age, :town

  setters :height
  getters :name
end

Person.class_eval do
  def initialize(name:)
    @name = name
  end
end

person = Person.new name: 'Norberto'

person.age = 28
person.town = 'Porto'
person.height = 1.70

puts person.name # Norberto
puts person.age  # 28
puts person.town # Porto