1  #!/usr/bin/env python3
       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 ESC[4;38;5;81mDisc(ESC[4;38;5;149mTurtle):
      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 ESC[4;38;5;81mTower(ESC[4;38;5;149mlist):
      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()