# Zwraca wiek obliczany na podstawie daty urodzenia
def age
  return if birthdate.nil?
  today = Date.today
  if (today.month > birthdate.month) or
    (today.month == birthdate.month and today.day >= birthdate.day)
    # Urodziny ju byy w tym roku
    today.year - birthdate.year
  else
    today.year - birthdate.year - 1
  end
end

