使用 Python 海龟鼠标移动获得“超过最大递归深度”

Question

此代码应利用鼠标移动事件在当前鼠标位置绘制一个点：

import turtle

def motion(event):

    x, y = event.x, event.y

    turtle.goto(x-300, 300-y)

    turtle.dot(5, "red")

turtle.pu()

turtle.setup(600, 600)

turtle.hideturtle()

canvas = turtle.getcanvas()

canvas.bind("<Motion>", motion)

如果鼠标移动得很慢，代码会按预期工作几秒钟或更长时间。然后它抛出：

>>> 

====================== RESTART: C:/code/turtle_move.py 

======================

>>> Exception in Tkinter callback

Traceback (most recent call last):

  File "C:\Users\...\AppData\Local\Programs\Python\Python36-32\lib\tkinter\__init__.py", line 1698, in __call__

    args = self.subst(*args)

  File "C:\Users\...\AppData\Local\Programs\Python\Python36-32\lib\tkinter\__init__.py", line 1428, in _substitute

    e.type = EventType(T)

RecursionError: maximum recursion depth exceeded

=============================== RESTART: Shell 

===============================

>>>

任何帮助深表感谢。

Answer 1

问题是当您的事件处理程序仍在处理前一个事件时，一个新事件进来了，因此事件处理程序从事件处理程序内部被调用，这看起来像一个递归！修复方法是在事件处理程序中禁用事件绑定：from turtle import Screen, Turtledef motion(event):&nbsp; &nbsp; canvas.unbind("<Motion>")&nbsp; &nbsp; turtle.goto(event.x - 300, 300 - event.y)&nbsp; &nbsp; turtle.dot(5, "red")&nbsp; &nbsp; canvas.bind("<Motion>", motion)screen = Screen()screen.setup(600, 600)turtle = Turtle(visible=False)turtle.speed('fastest')turtle.penup()canvas = screen.getcanvas()canvas.bind("<Motion>", motion)screen.mainloop()