adding attributes to a Ruby object dynamically

Question

I have an object created, and I want, based on some conditional check, to add some attributes to this object. How can I do this? To explain what I want:

A=O         


        

Answer 1

class Person; end
person = Person.new
person.age # throws NoMethodError

if true
  person.singleton_class.module_eval { attr_accessor :age }
end

person.age = 123
person.age #=> 123

person2 = Person.new
person2.age #=> throws NoMethodError