Do exercise 13.31 on pages 479-480.
In addition to the parts
(a)-(c) listed there, do the following part (d): The object contains
four normal images and an integer in the range 0 to 3. The four
images are all four rotations of the original, and the integer
specifies which one is currently active. The mutator just updates the
integer, as in parts (b) and (c). The selector retrieves one of the
four images, using the integer to select which.
For testing, you'll want to
(load "~mc27/labs/quilting/quilting.scm")
from your first MCS-177 lab. This will define images
like test-bb and nova-bb as well as
quarter-turn-right.