Error: _tkinter.TclError: can't invoke "wm" command: application has been destroyed

Question

I have three classes on three different files, to get User inputs through GUI

#file1
class GetInfo1():
    def getInfo1():
        #my code
        return info1
#file2
 class GetInfo2():
    def getInfo2():
        #my code
        return info2
 #file3
 class GetInfo3():
    def getInfo3():
        #my code
        return info3

calling these methods from different file Getinformation.py that file would be

from GetInfo1 import *
from GetInfo2 import *
from GetInfo3 import *

object1 = GetInfo1()
getInfor1 = object1.getInfo1()
print getInfor1

object2 = GetInfo2()
getInfor2 = object2.getInfo2()
print getInfor2

object3 = GetInfo3()
getInfor3 = object3.getInfo3()
print getInfor3

Classes are as follows:

from Tkinter import *

root = Tk()
app = Frame(root)

entry = Entry(app)
entry.grid()


class GetInfo1():

def OnClick(self):
    global input1
    input1 = entry.get()
    #print ("You have entered %s"%input1)
    root.destroy()
    return input1

def getInfo1(self):

    '''Window'''
    global input1
    root.title("Input Permutation Range ")
    root.geometry("300x200")
    app.grid()
    label = Label (app, text="Please Enter the propogation range ( 2 - 4)")
    label.grid()

    '''Button'''
    Object2 = AskPermutationRange()
    button = Button (app, text="Submit", command=Object2.OnClick)
    button.grid()
    root.focus_set()
    root.mainloop()
    return input1

Getting getInfor1, getInfor2 as specified but while running third object getting error _tkinter.TclError: can't invoke "wm" command: application has been destroyed How can i re invoke app again. thanks in advance

Solution

All that message means is that you're calling one of the "wm" commands (eg: wm_title, wm_geometry, and a few others) after you've destroyed the root window. (note: "geometry" and "title" are simple shortcuts to "wm_geometry" and "wm_title").

You're using tkinter in a highly unusual way. Tkinter was designed for you to create a single instance of Tk, and call mainloop exactly once. Is there a reason why you need to stop and start Tkinter multiple times in the course of your application? If all you need to do is pop up some modal dialogs and wait for the user to enter data, you can do that without creating a new instance of Tk every time.