Learn to Program, 2nd Edition

Creating Classes

We’ve now seen a smattering of different classes. However, it’s easy to come up with kinds of objects that Ruby doesn’t have—objects you’d like it to have. Fear not; creating a new class is as easy as extending an old one. Let’s say we wanted to make some dice in Ruby, for example. Here’s how we could make the Die class:

class Die
  def roll
    1 + rand(6)
  end
end
#  Let's make a couple of dice...
dice = [Die.new, Die.new]
#  ...and roll them.
dice.each do |die|
  puts die.roll
end

4
2

(If you skipped the section on random numbers, rand(6) just gives a random number between 0 and 5.) And that’s it! These are objects of our very own. Roll the dice a few times (run the program again), and watch what turns up.

We can define all ...