1 #!/usr/bin/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     hanoi(6, t1, t2, t3)

    54     write("press STOP button to exit",

    55           align="center", font=("Courier", 16, "bold"))

    56 

    57 def main():

    58     global t1, t2, t3

    59     ht(); penup(); goto(0, -225)   # writer turtle

    60     t1 = Tower(-250)

    61     t2 = Tower(0)

    62     t3 = Tower(250)

    63     # make tower of 6 discs

    64     for i in range(6,0,-1):

    65         t1.push(Disc(i))

    66     # prepare spartanic user interface ;-)

    67     write("press spacebar to start game",

    68           align="center", font=("Courier", 16, "bold"))

    69     onkey(play, "space")

    70     listen()

    71     return "EVENTLOOP"

    72 

    73 if __name__=="__main__":

    74     msg = main()

    75     print msg

    76     mainloop()