如何在函数完成前让tk显示某些内容

Question

我有一段代码，它可以从网上的列表中下载指定的文件。在下载的过程中，会显示一个加载界面，里面有一个标签告诉用户正在下载哪个文件，还有一个进度条，表示正在进行中。下载的功能运行得很好，但问题是tkinter（一个用来做图形界面的库）在下载完成之前都不显示任何东西，只在最后才显示“下载完成”的标签。我想知道怎么才能让tkinter在函数执行完之前就显示窗口。

我已经尝试过：

把代码拆分成多个函数
添加一个sleep函数，看看减慢速度是否有帮助

为了说明我所说的，我用一些示例替换了原来的代码。有没有人知道怎么让tkinter更积极地更新（在函数完成之前）？

#Imports
import urllib.request as ur
import os
from tkinter import *
import tkinter.ttk as ttk
import time as T

#Globals
tk = None
where = None
progressbar = None
progresstitle = None
progressinfo = None
transfer = None

#Make sure that the download directory exists
def checkdir(filename):
    directory = os.path.dirname(filename)
    try:
        os.stat(directory)
    except:
        os.mkdir(directory)  

#First part (read q to see why I split up)
def part1():
    #Get Globals
    global tk
    global where
    global progressbar
    global progresstitle
    global progressinfo
    global transfer

    #Create Window
    tk = Tk()
    tk.title("Downloading...")

    #Find out the location of the online files to download by reading the online txt file which contains their locations
    where = str(ur.urlopen("http://example.com/whatfilestodownload.txt").read())
    where = where[2:(len(where)-1)]
    where = where.split(";")
    #Create the progress bar
    progressbar = ttk.Progressbar(tk, orient=HORIZONTAL, length=200, mode='indeterminate')
    progressbar.grid(row = 2, column = 0)
    #Create the labels
    progresstitle = Label(tk, text = "Downloading Files!", font = ("Helvetica", 14))
    progresstitle.grid(row = 0, column = 0)
    progressinfo = Label(tk, text = "Starting Download...", font = ("Helvetica", 10))
    progressinfo.grid(row = 1, column = 0)

    #Engage Part Two
    part2()

#Part Two
def part2():
    #Get Globals
    global tk
    global where
    global progressbar
    global progresstitle
    global progressinfo
    global transfer
    #Repeat as many times as files described in the only file describing .txt
    for x in where
        #The online file contains "onlinelocation:offlinelocation" This splits them up
        x1 = x.split(":")[0]
        x2 = x.split(":")[1]

        #Read the online file and update labels
        transfer = None
        progressinfo.config(text = str("Downloading " + x2 + "..."))
        transfer = str(ur.urlopen("http://example.com/" + x1).read())
        progressinfo.config(text = str("Configuring downloaded file..."))
        transfer = transfer [2:(len(transfer)-1)]

        #Fix python turning "\n" to "\\n" by reversing
        transfer = transfer.split("\\n")
        transtemp = ""
        for x in transfer:
            transtemp = transtemp + "\n" + x
        transfer = transtemp[1:len(transtemp)]
        progressinfo.config(text = str("Installing " + x2 + "..."))
        tw = None
        checkdir(str(os.getcwd()+"/Downladed/"+x2))
        tw = open(str(os.getcwd()+"/Downloaded/"+x2), "w")
        tw.write(transfer)
        tw.close()
        #See if waiting helps
        T.sleep(0.5)
    part3()
def part3():
    #Get Globals
    global tk
    global where
    global progressbar
    global progresstitle
    global progressinfo
    global transfer
    #Final Screen
    progressbar.grid_remove()
    progressinfo.grid_remove()
    progresstitle.config(text="You have downloaded\n the required files!")
    progressbar.stop()

part1()

tkinter 多线程文件下载 gui 进度条事件循环界面更新加载界面

如何在函数完成前让tk显示某些内容

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