lsp_square_rect.rb

class Rectangle
  attr_accessor :width, :height, :top_left_corner
  def new(width,height,top_left) ... ; end
  def area ... ; end
  def perimeter ... ; end
end
# A square is just a special case of rectangle...right?
class Square < Rectangle
  # ooops...a square has to have width and height equal
  attr_reader :width, :height, :side
  def width=(w)  ; @width = @height = w ; end
  def height=(w) ; @width = @height = w ; end
  def side=(w)   ; @width = @height = w ; end
end
# But is a Square really a kind of Rectangle?
class Rectangle
  def make_twice_as_wide_as_high(dim)
    self.width = 2*dim
    self.height = dim           # doesn't work!
  end
end