raw_input stops GUI from appearing

Question

I have written a program in Python that allow me to change the names of many files all at once. I have one issue that is quite odd.

When I use raw_input to get my desired extension, the GUI will not launch. I don't get any errors, but the window will never appear.

I tried using raw_input as a way of getting a file extension from the user to build the file list. This program will works correctly when raw_input is not used.The section of code that I am referring to is in my globList function. For some reason when raw_imput is used the window will not launch.

import os
import Tkinter
import glob
from Tkinter import *

def changeNames(dynamic_entry_list, filelist):
    for index in range(len(dynamic_entry_list)):
        if(dynamic_entry_list[index].get() != filelist[index]):
            os.rename(filelist[index], dynamic_entry_list[index].get())

    print "The files have been updated!" 



def drawWindow(filelist):

    dynamic_entry_list = []
    my_row = 0
    my_column = 0
    for name in filelist:
        my_column = 0
        label = Tkinter.Label(window, text = name, justify = RIGHT)
        label.grid(row = my_row, column = my_column)

        my_column = 1
        entry = Entry(window, width = 50)
        dynamic_entry_list.append(entry)
        entry.insert(0, name)
        entry.grid(row = my_row, column = my_column)

        my_row += 1       
    return dynamic_entry_list


def globList(filelist):
    #ext = raw_input("Enter the file extension:")
    ext = ""
    desired = '*' + ext
    for name in glob.glob(desired):
        filelist.append(name)




filelist = []
globList(filelist)
window = Tkinter.Tk()
user_input = drawWindow(filelist)
button = Button(window, text = "Change File Names", command = (lambda      e=user_input: changeNames(e, filelist)))
button.grid(row = len(filelist) + 1 , column = 1)

window.mainloop()

Is this a problem with raw_input?

What would be a good solution to the problem?

Answer 1

This is how tkinter is defined to work. It is single threaded, so while it's waiting for user input it's truly waiting. mainloop must be running so that the GUI can respond to events, including internal events such as requests to draw the window on the screen.

Generally speaking, you shouldn't be mixing a GUI with reading input from stdin. If you're creating a GUI, get the input from the user via an entry widget. Or, get the user input before creating the GUI.

A decent tutorial on popup dialogs can be found on the effbot site: http://effbot.org/tkinterbook/tkinter-dialog-windows.htm