Demo/turtle/tdemo_minimal_hanoi.py

   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()