jpayne@68: #!/usr/bin/env python3
jpayne@68: """       turtle-example-suite:
jpayne@68: 
jpayne@68:          tdemo_minimal_hanoi.py
jpayne@68: 
jpayne@68: A minimal 'Towers of Hanoi' animation:
jpayne@68: A tower of 6 discs is transferred from the
jpayne@68: left to the right peg.
jpayne@68: 
jpayne@68: An imho quite elegant and concise
jpayne@68: implementation using a tower class, which
jpayne@68: is derived from the built-in type list.
jpayne@68: 
jpayne@68: Discs are turtles with shape "square", but
jpayne@68: stretched to rectangles by shapesize()
jpayne@68:  ---------------------------------------
jpayne@68:        To exit press STOP button
jpayne@68:  ---------------------------------------
jpayne@68: """
jpayne@68: from turtle import *
jpayne@68: 
jpayne@68: class Disc(Turtle):
jpayne@68:     def __init__(self, n):
jpayne@68:         Turtle.__init__(self, shape="square", visible=False)
jpayne@68:         self.pu()
jpayne@68:         self.shapesize(1.5, n*1.5, 2) # square-->rectangle
jpayne@68:         self.fillcolor(n/6., 0, 1-n/6.)
jpayne@68:         self.st()
jpayne@68: 
jpayne@68: class Tower(list):
jpayne@68:     "Hanoi tower, a subclass of built-in type list"
jpayne@68:     def __init__(self, x):
jpayne@68:         "create an empty tower. x is x-position of peg"
jpayne@68:         self.x = x
jpayne@68:     def push(self, d):
jpayne@68:         d.setx(self.x)
jpayne@68:         d.sety(-150+34*len(self))
jpayne@68:         self.append(d)
jpayne@68:     def pop(self):
jpayne@68:         d = list.pop(self)
jpayne@68:         d.sety(150)
jpayne@68:         return d
jpayne@68: 
jpayne@68: def hanoi(n, from_, with_, to_):
jpayne@68:     if n > 0:
jpayne@68:         hanoi(n-1, from_, to_, with_)
jpayne@68:         to_.push(from_.pop())
jpayne@68:         hanoi(n-1, with_, from_, to_)
jpayne@68: 
jpayne@68: def play():
jpayne@68:     onkey(None,"space")
jpayne@68:     clear()
jpayne@68:     try:
jpayne@68:         hanoi(6, t1, t2, t3)
jpayne@68:         write("press STOP button to exit",
jpayne@68:               align="center", font=("Courier", 16, "bold"))
jpayne@68:     except Terminator:
jpayne@68:         pass  # turtledemo user pressed STOP
jpayne@68: 
jpayne@68: def main():
jpayne@68:     global t1, t2, t3
jpayne@68:     ht(); penup(); goto(0, -225)   # writer turtle
jpayne@68:     t1 = Tower(-250)
jpayne@68:     t2 = Tower(0)
jpayne@68:     t3 = Tower(250)
jpayne@68:     # make tower of 6 discs
jpayne@68:     for i in range(6,0,-1):
jpayne@68:         t1.push(Disc(i))
jpayne@68:     # prepare spartanic user interface ;-)
jpayne@68:     write("press spacebar to start game",
jpayne@68:           align="center", font=("Courier", 16, "bold"))
jpayne@68:     onkey(play, "space")
jpayne@68:     listen()
jpayne@68:     return "EVENTLOOP"
jpayne@68: 
jpayne@68: if __name__=="__main__":
jpayne@68:     msg = main()
jpayne@68:     print(msg)
jpayne@68:     mainloop()