python - 需要帮助理解 python : 中的此错误文本

Question

好吧，基本上我写了一个不太漂亮的 GUI，它给出了随机的简单数学问题。它就像我想要的那样工作。然而，每次我点击进入时，空闲的 Shell 都会向我吐出红色。尽管如此，就像我说的那样，它继续按照我想要的方式运行。所以我无法理解为什么我的代码的这个特定部分会导致问题。抱歉代码太长:

from tkinter import Label, Frame, Entry, Button, LEFT, RIGHT, END
from tkinter.messagebox import showinfo
import random

class Ed(Frame):
    'Simple arithmetic education app'
    def __init__(self,parent=None):
        'constructor'
        Frame.__init__(self, parent)
        self.pack()
        self.tries = 0
        Ed.make_widgets(self)
        Ed.new_problem(self)

    def make_widgets(self):
        'defines Ed widgets'
        self.entry1 = Entry(self, width=20, bg="gray", fg ="black")
        self.entry1.grid(row=0, column=0, columnspan=4)
        self.entry1.pack(side = LEFT)
        self.entry2 = Entry(self, width=20, bg="gray", fg ="black")
        self.entry2.grid(row=2, column=2, columnspan=4)
        self.entry2.pack(side = LEFT)
        Button(self,text="ENTER", command=self.evaluate).pack(side = RIGHT)

    def new_problem(self):
        'creates new arithmetic problem'
        opList = ["+", "-"]
        a = random.randrange(10+1)
        b = random.randrange(10+1)
        op = random.choice(opList)
        if b > a:
            op = "+"
        self.entry1.insert(END, a)
        self.entry1.insert(END, op)
        self.entry1.insert(END, b)


    def evaluate(self):
        'handles button "Enter" clicks by comparing answer in entry to correct result'
        result = eval(self.entry1.get())
        if result == eval(self.entry2.get()):
            self.tries += 1
            showinfo(title="Huzzah!", message="That's correct! Way to go! You got it in {} tries.".format(self.tries))
            self.entry1.delete(0, END)
            self.entry2.delete(0, END)
            self.entry1.insert(END, self.new_problem())
        else:
            self.tries += 1
            self.entry2.delete(0, END)

这是我收到的消息:

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Python32\lib\tkinter\__init__.py", line 1399, in __call__
    return self.func(*args)
  File "C:\Python32\Python shit\csc242hw4\csc242hw4.py", line 55, in evaluate
    self.entry1.insert(END, self.new_problem())
  File "C:\Python32\lib\tkinter\__init__.py", line 2385, in insert
    self.tk.call(self._w, 'insert', index, string)
_tkinter.TclError: wrong # args: should be ".52882960.52883240 insert index text"

Answer 1

错误消息说 Tkinter 认为它得到了错误数量的参数。

进一步回顾回溯，我们看到这一行导致了错误:

File "C:\Python32\Python shit\csc242hw4\csc242hw4.py", line 55, in evaluate
    self.entry1.insert(END, self.new_problem())

但这似乎是正确的参数数量!那么这是怎么回事？

问题是 self.new_problem() 返回 None。看起来 Python 的 Tkinter 包装器在参数为 None 时不会传递参数。

要解决此问题，请删除对 insert 的调用并将第 55 行更改为

self.new_problem()

这是有效的，因为您已经从 new_problem 内部调用了 self.entry.insert。