python - 调用 python 对象时超出最大递归深度

Question

我的目标是实例化一个名为箭头的类，这样我就可以拥有比 1 个更多的箭头。我想从坐标 200、200 开始，并希望每 100 毫秒将 x 增加 15。但是，当我尝试执行此代码时，出现以下错误:

  File "game.py", line 25, in moveArrow
    self.after(100, self.moveArrow(arrow, xCoord+15, yCoord)) #repeat, changing x
  File "game.py", line 24, in moveArrow
    arrow.place(x = xCoord, y = yCoord) #replace with new x,y
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1860, in place_configure
    + self._options(cnf, kw))
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1055, in _options
    elif isinstance(v, (tuple, list)):
RuntimeError: maximum recursion depth exceeded while calling a Python object

“文件“game.py”，第 25 行，在 move Arrow self.after(100, self.moveArrow(arrow, xCoord+15, yCoord)) #repeat, changing x 中也经常重复。

from Tkinter import *
from random import randint
from PIL import ImageTk, Image

class App(Frame):
        def __init__(self, master=None):
                Frame.__init__(self, master, height=400, width=400)
                self.master = master
                self.master.bind('<Shift_L>', self.createArrow)
        def createArrow(self, event):
                self.arrow = Arrow(self)
                self.arrow.moveArrow(self.arrow, 200, 200)

class Arrow(Frame):
        def __init__(self, master):
                Frame.__init__(self, master)
                self.arrowImage = ImageTk.PhotoImage(Image.open("arrow.gif"))
                Label(self, image=self.arrowImage).pack()
        def moveArrow(self, arrow, xCoord, yCoord):
                arrow.place_forget()
                arrow.place(x = xCoord, y = yCoord)
                self.after(100, self.moveArrow(arrow, xCoord+15, yCoord))

root = Tk()
root.title("Mein erstes Spiel")
app = App(master=root).pack()
root.mainloop()

Answer 1

关于问题的根源是这一行的其他答案是正确的:

self.after(100, self.moveArrow(arrow, xCoord+15, yCoord))

但答案是特定于 Tkinter 的:

查看 after 的文档方法以查看如何正确实现此方法。像普通函数调用一样调用它会做到这一点，并在控制流到达该函数调用时将您的程序抛入无限循环。当您使用 after 时，您有两个选择:

传递时间参数，然后是回调，然后是回调参数:

self.after(100, self.moveArrow, arrow, xCoord+15, yCoord)

或者，使用 lambda 表达式来保存函数调用:

self.after(100, lambda: self.moveArrow(arrow, xCoord+15, yCoord))