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      1 #!/usr/bin/env python
      2 """       turtle-example-suite:
      3 
      4          tdemo_minimal_hanoi.py
      5 
      6 A minimal 'Towers of Hanoi' animation:
      7 A tower of 6 discs is transferred from the
      8 left to the right peg.
      9 
     10 An imho quite elegant and concise
     11 implementation using a tower class, which
     12 is derived from the built-in type list.
     13 
     14 Discs are turtles with shape "square", but
     15 stretched to rectangles by shapesize()
     16  ---------------------------------------
     17        To exit press STOP button
     18  ---------------------------------------
     19 """
     20 from turtle import *
     21 
     22 class Disc(Turtle):
     23     def __init__(self, n):
     24         Turtle.__init__(self, shape="square", visible=False)
     25         self.pu()
     26         self.shapesize(1.5, n*1.5, 2) # square-->rectangle
     27         self.fillcolor(n/6., 0, 1-n/6.)
     28         self.st()
     29 
     30 class Tower(list):
     31     "Hanoi tower, a subclass of built-in type list"
     32     def __init__(self, x):
     33         "create an empty tower. x is x-position of peg"
     34         self.x = x
     35     def push(self, d):
     36         d.setx(self.x)
     37         d.sety(-150+34*len(self))
     38         self.append(d)
     39     def pop(self):
     40         d = list.pop(self)
     41         d.sety(150)
     42         return d
     43 
     44 def hanoi(n, from_, with_, to_):
     45     if n > 0:
     46         hanoi(n-1, from_, to_, with_)
     47         to_.push(from_.pop())
     48         hanoi(n-1, with_, from_, to_)
     49 
     50 def play():
     51     onkey(None,"space")
     52     clear()
     53     try:
     54         hanoi(6, t1, t2, t3)
     55         write("press STOP button to exit",
     56               align="center", font=("Courier", 16, "bold"))
     57     except Terminator:
     58         pass  # turtledemo user pressed STOP
     59 
     60 def main():
     61     global t1, t2, t3
     62     ht(); penup(); goto(0, -225)   # writer turtle
     63     t1 = Tower(-250)
     64     t2 = Tower(0)
     65     t3 = Tower(250)
     66     # make tower of 6 discs
     67     for i in range(6,0,-1):
     68         t1.push(Disc(i))
     69     # prepare spartanic user interface ;-)
     70     write("press spacebar to start game",
     71           align="center", font=("Courier", 16, "bold"))
     72     onkey(play, "space")
     73     listen()
     74     return "EVENTLOOP"
     75 
     76 if __name__=="__main__":
     77     msg = main()
     78     print msg
     79     mainloop()
     80