ruby_oop

require 'time'
class Person
   attr_accessor :name, :age, :sex, :birth_date, :birth_place, :death_date

  ## class methods
   def Person.load_with_info(n, bdate, ddate=nil)
      a = Person.new
      a.name = n
      a.birth_date = bdate
      a.death_date = ddate
      return a
   end
   
   ## instance methods
   def age
      ((alive? ? Time.now : Time.parse(death_date)) - Time.parse(birth_date)).to_i / 60 / 60 / 24 / 365 
   end

   def alive?
     death_date.nil?
   end   
      
end   


class Musician < Person
  attr_accessor :discography
end

class Painter < Person
  attr_accessor :published_works
end