my_class.rb

class MyClass
  def initialize(&block)
    instance_eval(&block)
  end

  def say(message)
    @message = message
    self
  end

  def to(user)
    puts "Hey #{user}, I have a message for you: #{@message}"
  end
end

MyClass.new { say('Hello').to('Ryan') }

person.rb

#bin/rails g model Person name:string age:integer hair_color:integer
class Person < ActiveRecord::Base
  validates_presence_of :name
  validates :age, numericality: { greater_than: 0 }

  enum hair_color: [ :brown, :blond,  :black]
end