Python Turtle for loop無限運行

Question

我有一些Turtle代碼已經成功運行過，然后才能在Repl.it的Python中使用Turtle IDE繪制Sierpinski密封墊，但是最近當我再次嘗試運行它時，它成功完成了所有工作，除非遇到了for循環，烏龜只是開始旋轉，直到很久以后才執行for循環中的行。

我已將print（i）添加到forloop中，並且它反復打印0就像是一個無限循環

import turtle
from turtle import *

t = Turtle()
t.speed(0)
t.shape('turtle')
t.color('dark green')

def SGRules(char):
  if char == 'F':
    return 'F+F-F-F+F'
  else:
    return char

def processStr(oldstr, Fractal_Rules):
  newstr = ""
  for char in oldstr:
    newstr = newstr + Fractal_Rules(char)
  return newstr

def createLSystem(iteration, axiom, Fractal_Rules):
  startstr = axiom
  endstr = ""
  for i in range(iteration):
    endstr = processStr(startstr, Fractal_Rules)
    startstr = endstr
  return endstr

def drawLSystem(aturtle, lsys, angle, length):
  for cmd in lsys:
    if cmd == 'F':
      aturtle.forward(length)
    elif cmd == '+':
      aturtle.left(angle)
    elif cmd == '-':
      aturtle.right(angle)

sgstr = createLSystem(4, 'F', SGRules)
print(sgstr)
drawLSystem(t, sgstr, 120, 20)
for i in range(2):
  print(i)
  t.left(120)
  t.forward(20 * 2**4)

一旦到達右下角，它應該只繪制剩余的外部三角形的2個邊。

Answer 1

您的代碼清理對我而言在repl.it和Python控制台中運行良好：

from turtle import Screen, Turtle

ANGLE = 120
LENGTH = 20
ITERATIONS = 4

def SGRules(character):
    if character == 'F':
        return 'F+F-F-F+F'

    return character

def processStr(string, rules):
    new_string = ""

    for character in string:
        new_string += rules(character)

    return new_string

def createLSystem(iterations, axiom, rules):
    string = ""

    for _ in range(iterations):
        string = processStr(axiom, rules)
        axiom = string

    return string

def drawLSystem(turtle, lsys, angle, length):
    for command in lsys:
        if command == 'F':
            turtle.forward(length)
        elif command == '+':
            turtle.left(angle)
        elif command == '-':
            turtle.right(angle)

yertle = Turtle('turtle')
yertle.speed('fastest')
yertle.shape('turtle')
yertle.color('dark green', 'light green')

sg_string = createLSystem(ITERATIONS, 'F', SGRules)
print(sg_string)
drawLSystem(yertle, sg_string, ANGLE, LENGTH)

for _ in range(2):
    yertle.left(ANGLE)
    yertle.forward(LENGTH * 2 ** ITERATIONS)

screen = Screen()
screen.mainloop()

盡管一旦我在末尾向tkinter的事件循環中添加了轉移以防止窗口關閉，您的原始代碼在Python控制台中的運行情況就很好。