jpayne@69: #!/usr/bin/env python3
jpayne@69: """       turtle-example-suite:
jpayne@69: 
jpayne@69:          tdemo_minimal_hanoi.py
jpayne@69: 
jpayne@69: A minimal 'Towers of Hanoi' animation:
jpayne@69: A tower of 6 discs is transferred from the
jpayne@69: left to the right peg.
jpayne@69: 
jpayne@69: An imho quite elegant and concise
jpayne@69: implementation using a tower class, which
jpayne@69: is derived from the built-in type list.
jpayne@69: 
jpayne@69: Discs are turtles with shape "square", but
jpayne@69: stretched to rectangles by shapesize()
jpayne@69:  ---------------------------------------
jpayne@69:        To exit press STOP button
jpayne@69:  ---------------------------------------
jpayne@69: """
jpayne@69: from turtle import *
jpayne@69: 
jpayne@69: class Disc(Turtle):
jpayne@69:     def __init__(self, n):
jpayne@69:         Turtle.__init__(self, shape="square", visible=False)
jpayne@69:         self.pu()
jpayne@69:         self.shapesize(1.5, n*1.5, 2) # square-->rectangle
jpayne@69:         self.fillcolor(n/6., 0, 1-n/6.)
jpayne@69:         self.st()
jpayne@69: 
jpayne@69: class Tower(list):
jpayne@69:     "Hanoi tower, a subclass of built-in type list"
jpayne@69:     def __init__(self, x):
jpayne@69:         "create an empty tower. x is x-position of peg"
jpayne@69:         self.x = x
jpayne@69:     def push(self, d):
jpayne@69:         d.setx(self.x)
jpayne@69:         d.sety(-150+34*len(self))
jpayne@69:         self.append(d)
jpayne@69:     def pop(self):
jpayne@69:         d = list.pop(self)
jpayne@69:         d.sety(150)
jpayne@69:         return d
jpayne@69: 
jpayne@69: def hanoi(n, from_, with_, to_):
jpayne@69:     if n > 0:
jpayne@69:         hanoi(n-1, from_, to_, with_)
jpayne@69:         to_.push(from_.pop())
jpayne@69:         hanoi(n-1, with_, from_, to_)
jpayne@69: 
jpayne@69: def play():
jpayne@69:     onkey(None,"space")
jpayne@69:     clear()
jpayne@69:     try:
jpayne@69:         hanoi(6, t1, t2, t3)
jpayne@69:         write("press STOP button to exit",
jpayne@69:               align="center", font=("Courier", 16, "bold"))
jpayne@69:     except Terminator:
jpayne@69:         pass  # turtledemo user pressed STOP
jpayne@69: 
jpayne@69: def main():
jpayne@69:     global t1, t2, t3
jpayne@69:     ht(); penup(); goto(0, -225)   # writer turtle
jpayne@69:     t1 = Tower(-250)
jpayne@69:     t2 = Tower(0)
jpayne@69:     t3 = Tower(250)
jpayne@69:     # make tower of 6 discs
jpayne@69:     for i in range(6,0,-1):
jpayne@69:         t1.push(Disc(i))
jpayne@69:     # prepare spartanic user interface ;-)
jpayne@69:     write("press spacebar to start game",
jpayne@69:           align="center", font=("Courier", 16, "bold"))
jpayne@69:     onkey(play, "space")
jpayne@69:     listen()
jpayne@69:     return "EVENTLOOP"
jpayne@69: 
jpayne@69: if __name__=="__main__":
jpayne@69:     msg = main()
jpayne@69:     print(msg)
jpayne@69:     mainloop()