Learn how to build flexible interfaces using instance_eval in #ruby

flexible interface.rb

class Person
  def name(n)
    @name = n
    self
  end
  def age(a)
    @age = a
    self
  end

  def to_s
    "Hi there I am #{@name} and I am #{@age} years old!"
  end
  class << self
    def people
      @@people ||= []
    end
    def add(&block)
      people << new.instance_eval(&block)
    end
  end
end

person = Person.add { name 'Ahmad Hamdi'; age 22 }
puts person # => Hi there I am Ahmad Hamdi and I am 22 years old!
another = Person.add { name 'Ashraf'; age 55 }
puts another # => Hi there I am Ashraf and I am 55 years old!
p Person.people