/Demo/turtle/tdemo_minimal_hanoi.py

 1#!/usr/bin/python
 2"""       turtle-example-suite:
 3
 4         tdemo_minimal_hanoi.py
 5
 6A minimal 'Towers of Hanoi' animation:
 7A tower of 6 discs is transferred from the
 8left to the right peg.
 9
10An imho quite elegant and concise
11implementation using a tower class, which
12is derived from the built-in type list.
13
14Discs are turtles with shape "square", but
15stretched to rectangles by shapesize()
16 ---------------------------------------
17       To exit press STOP button
18 ---------------------------------------
19"""
20from turtle import *
21
22class 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
30class 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
44def 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
50def 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
57def 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
73if __name__=="__main__":
74    msg = main()
75    print msg
76    mainloop()