Python Tkinter 更新标签文本会将旧文本保留在那里，直到函数退出

Question

我正在使用 python 和 tkinter 构建一个简单的 GUI，这是一个 Magic 8 Ball 问题。当我尝试更新 ASK 函数内响应标签显示的文本时，我的问题出现了。我想尝试更新几次，以便它在给出答案之前在 --- 和“[Blank]”之间闪烁几秒钟。但它似乎只是将新文本覆盖在旧文本之上，直到 ASK 功能完成，此时最后放置的文本是唯一剩下的文本。

这仅仅是因为我只能在函数内更新一次吗？或者有一个简单的方法可以解决这个问题吗？

代码，尽可能多地删掉以显示错误:

import time
import random
from tkinter import *

responses=[]
responses.append("No")
responses.append("Yes")
responses.append("I don't think so")    

class TheGUI:
    def __init__(self, master):
        self.master = master
        master.title("Python Magic 8 Ball GUI")

        self.label = Label(self.master, text="Enter a Question you would like to ask (no to quit):")
        self.label.pack()

        self.enterplace = Entry(self.master)
        self.enterplace.pack()

        self.labeltext=StringVar()
        self.labeltext.set("--")
        self.response = Label(self.master, justify=CENTER, textvariable=self.labeltext)
        self.response.pack()

        self.frame = Frame(self.master)
        self.frame.pack()

        self.greet_button = Button(self.frame, text="Ask", command=self.ask)
        self.greet_button.pack(side=LEFT)

        self.close_button = Button(self.frame, text="Clear", command=self.clear)
        self.close_button.pack(side=LEFT)

    # This is the function in question
    def ask(self):
        the_q = self.enterplace.get()

        if the_q == "no":
            self.labeltext.set("Okay, Goodbye..")
            time.sleep(2)
            self.master.quit
        else:
            self.labeltext.set("Let me think for a moment")
            self.master.update_idletasks()
            time.sleep(2)

            # Here, when I update the label to be ---, the previous text 
            # remains as a background, and only disappears once this 
            # function has exited. I was initially trying to make the --- 
            # blink once or twice, but ran into this error

            self.labeltext.set("---")
            self.master.update_idletasks()
            time.sleep(2)

            self.labeltext.set(random.choice(responses))
            self.master.update_idletasks()
            time.sleep(2)

    def clear(self):
        self.labeltext.set("")
        self.master.update_idletasks()


root = Tk()
my_gui = TheGUI(root)
root.mainloop()

下图显示了文本叠加，“让我想一下”和“我不这么认为”

Answer 1

你几乎一切都对!对我有用的是将 self.master.update_idletasks() 替换为 self.master.update()

        self.labeltext.set("Let me think for a moment")
        self.master.update()
        # self.master.update_idletasks()
        time.sleep(2)

        self.labeltext.set("---")
        self.master.update()
        # self.master.update_idletasks()
        time.sleep(2)
        self.labeltext.set(random.choice(responses))
        self.master.update()
        # self.master.update_idletasks()
        time.sleep(2)

但是我不明白为什么 update_idletasks() 在这种情况下不起作用......