Chapter 3: More Exercises

Chapter 3 - Inheritance

Exercise 1: Square class

Your next task is to create a subclass of Rectangle, named Square. Square should override the width= method to set both the width and height to the given value when called. It should do the same with the height= method. (Don’t worry about checking whether the values are negative.) All other methods should be inherited from Rectangle. The area method should work without any need to override it.

class Rectangle
  attr_reader :width, :height

  def width=(value)
    if value < 0
      raise "Width can't be negative!"
    end
    @width = value
  end

  def height=(value)
    if value < 0
      raise "Height can't be negative!"
    end
    @height = value
  end

  def area
    width * height
  end
end

class Square < Rectangle
  def width=(value)
    @width = value
    @height = value
  end

  def height=(value)
    @width = value
    @height = value
  end
end

square_1 = Square.new
square_1.height = 3
puts square_1.area # Displays: 9.
square_2 = Square.new
square_2.width = 4
puts square_2.area # Displays: 16.