ruby_oo_inheritance_simple.rb

class Shape
  def initialize(color)
    @color = color
  end

  def repr
    raise 'Abstract method, to be implemented on subclasses'
  end

  def draw
    paint(repr)
  end

  private
  def paint(repr)
    puts @color, repr
  end
end

class Triangle < Shape
  def initialize(color, sides)
    super(color)
    @sides = sides
  end

  def repr
    # It could be something more complex
    @sides
  end
end

class Square < Shape
  def initialize(color, side)
    super(color)
    @side = side
  end

  def repr
    # It could be something more complex
    @side
  end
end