使用线程和 tkinter 模块在 python 中停止线程并避免“RuntimeError”的最佳方法是什么？

Question

我在网上经历了多种解决方案，但它们需要大量代码，一旦您扩展，这些代码可能会令人困惑。是否有一种简单的方法可以停止线程并避免RuntimeError: threads can only be started once, 以便无限次调用线程。这是我的代码的简单版本：

import tkinter
import time
import threading

def func():

    entry.config(state='disabled')
    label.configure(text="Standby for  seconds")
    time.sleep(3)
    sum = 0
    for i in range(int(entry.get())):
        time.sleep(0.5)
        sum = sum+i
        label.configure(text=str(sum))
    entry.config(state='normal')

mainwindow = tkinter.Tk()
mainwindow.title('Sum up to any number')

entry = tkinter.Entry(mainwindow)
entry.pack()
label = tkinter.Label(mainwindow, text = "Enter an integer",font=("Arial",33))
label.pack()

print(entry.get())

button = tkinter.Button(mainwindow, text="Press me", command=threading.Thread(target=func).start)
button.pack()

Answer 1

虽然这是一种用更少的代码行完成工作的简单方法。我无法使用该.join()方法。但是，该应用程序似乎没有创建任何新线程。这通过threading.active_counts()方法是显而易见的。下面是代码：

import tkinter, threading, time

def calc():
    entry.config(state='disabled')
    label.configure(text="Standby for 3 seconds")
    time.sleep(3)
    sum = 0
    for i in range(int(entry.get())):
        time.sleep(0.5)
        sum = sum+i
        labelnum.configure(text=str(sum))
    button.config(state='normal')
    label.configure(text="Sum up to any number")
    entry.config(state='normal')

def func():
    t = threading.Thread(target=calc)
    t.start()
    #del t
    print('Active threads:',threading.active_count())


mainwindow = tkinter.Tk()
mainwindow.title('Sum up to any number')
entry = tkinter.Entry(mainwindow)
entry.pack()
label = tkinter.Label(mainwindow, text = "Enter an integer",font=("Arial",33))
label.pack()
labelnum = tkinter.Label(mainwindow, text="",font=('Arial',33))
labelnum.pack()
button = tkinter.Button(mainwindow, text="Press me", command=func)
button.pack()
mainwindow.mainloop()