neekers.rb

class Person
  def add_accessor(accessor_name)
    class << self; self; end.class_eval do
      attr_accessor accessor_name
    end
  end
end

person = Person.new
Person.add_accessor :name
Person.add_accessor :gender
person.name = "Peter Cooper"
person.gender = "male"
puts "#{person.name} is #{person.gender}"