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How to trigger again a callback function before the first call for that function has ended

Good morning,
What I am aiming for:
I want to create a button that when clicked triggers a call back function (even if that function is still running).
Module:
I am using tkinter
Problem:
When I trigger the button, the function runs, but then I cannot push the button again before the function has finished its run. I want to be able to push the button while the function is still running and have the function stop and run again from start.
My attempts:
I tried both a procedural and a OOP approach: both present the same problem
My attempt n1: Procedural approach
import time
import tkinter as tk # Import tkinter
from tkinter import ttk # Import ttk
def func():
for i in range (100):
print(i)
time.sleep(5)
win = tk.Tk() # Create instance of the Tk class
aButton = ttk.Button(win, text="Click Me!", command=func)
aButton.grid(column=0, row=0) # Adding a Button
win.mainloop() # Start GUI
My attempt n2: OOP approach
import time
import tkinter as tk # Import tkinter
from tkinter import ttk # Import ttk
class OOP():
def func(self):
for i in range (100):
print(i)
time.sleep(5)
def __init__(self):
win = tk.Tk() # Create instance of the Tk class
aButton = ttk.Button(win, text="Click Me!", command=self.func)
aButton.grid(column=0, row=0) # Adding a Button
win.mainloop() # Start GUI
oop = OOP()
Thanks

In tkinter, as with most GUI frameworks, there is a for loop running somewhere that constantly checks for user input. You are hijacking that loop to do your func processing. Tkinter can not check for user input, nor e.g. change the appearance of the button icon, because there is only one thread and you are using it.
What you will want to do is fire up a thread or process to do the work. There are lots of libraries to do parallel processing in elaborate ways if you have lots of background tasks but this will do for a single function (see also this answer).
import time
import tkinter as tk # Import tkinter
from tkinter import ttk # Import ttk
import threading
def button():
thread = threading.Thread(target=func, args=args)
thread.start()
def func():
for i in range (100):
print(i)
time.sleep(5)
win = tk.Tk() # Create instance of the Tk class
aButton = ttk.Button(win, text="Click Me!", command=button)
aButton.grid(column=0, row=0) # Adding a Button
win.mainloop() # Start GUI
If the process is long running, you might need to find a way to clean up the threads when they're done.

issue with tkinter messagebox

I'm using several tkinter messageboxes in my code. But ive noticed a problem with the showinfo messageboxes I've used in my code. Basically, I want a function to be called when the ok on the messagebox is pressed. Also, the user can choose not to proceed by just closing the messagebox. But, it looks like when I press the x icon to close the messagebox, the function is still called. Here is a minimum reproducible code to explain what i mean.
from tkinter import *
from tkinter import messagebox
root = Tk()
def func() :
Label(root,text="This is the text").pack()
msg = messagebox.showinfo("Loaded","Your saved state has been loaded")
if msg == "ok" :
func()
root.mainloop()
My question is, What should i do so that the function is not called when the x icon is pressed?

There are different types of messagebox, the one your using here is not what you actually should be using for your case. What you want is something called askyesno, or something that is prefixed by 'ask' because your code depend upon the users action. So you want to 'ask' the user, like:
from tkinter import *
from tkinter import messagebox
root = Tk()
def func() :
Label(root,text="This is the text").pack(oadx=10,pady=10)
msg = messagebox.askyesno("Loaded","Your saved state has been loaded")
if msg: #same as if msg == True:
func()
root.mainloop()
Here, askyesno like other 'ask' prefixed functions will return True or 1 if you click on the 'Yes' button, else it will return False or 0.
Also just something I realized now, showinfo, like other 'show' prefixed messagebox function, returns 'ok' either you press the button or close the window.
Some more 'ask' prefixed messageboxes ~ askokcancel, askquestion, askretrycancel, askyesnocancel. Take a look here

closing tkinter window together with messagebox error window

In my script I sometimes call my ErrorWindow class to show an error message. This creates an empty tkinter window and a messagebox error window. I either only want the messagebox window, or I want the tkinter window to close automatically when I close the error window.
I've tried two pieces of code:
class ErrorWindow:
def __init__(self,error_message):
self.error_window = tk.Tk()
messagebox.showerror("ERROR",error_message,command=self.close)
self.error_window.protocol("WM_DELETE_WINDOW", self.close)
self.error_window.mainloop()
def close(self):
self.error_window.destroy()
.
class ErrorWindow:
def __init__(self,error_message):
messagebox.showerror("ERROR",error_message) #automatically creates a tk window too
But even with the second one, the tkinter window remains after I close the messagebox.
How can I program the class so that I only have to press a button (either Ok or the X in the top right of a window) once to close all windows (whether that is one or two)?

You need to withdraw the main window:
class ErrorWindow:
def __init__(self,error_message):
if not tk._default_root: # check for existing Tk instance
error_window = tk.Tk()
error_window.withdraw()
messagebox.showerror("ERROR",error_message)
This has no business as a class. You should remake this a simple function.

You did not specify whether there is just one place or multiple places where you might want want an error message. If the latter, you can create and withdraw a tk window just once. I believe a wrapper function rather than class should be sufficient for your purposes.
import tkinter as tk
from tkinter import messagebox
root = tk.Tk()
# consider placing root to control where messagebox appears
root.withdraw()
def showerror(message):
messagebox.showerror('XYZ ERROR', message, parent=root)
To avoid possible problems, I always use an explicit master or parent for everything and never depend on _default_root.

The small function below will do the job. By setting the type you can choose for: info, warning or error message box, the default is 'Info'. You can set also the timeout, the default is 2.5 seconds.
def showMessage(message, type='info', timeout=2500):
import tkinter as tk
from tkinter import messagebox as msgb
root = tk.Tk()
root.withdraw()
try:
root.after(timeout, root.destroy)
if type == 'info':
msgb.showinfo('Info', message, master=root)
elif type == 'warning':
msgb.showwarning('Warning', message, master=root)
elif type == 'error':
msgb.showerror('Error', message, master=root)
except:
pass
Call the function as follow:
For message type 'Info' and timeout of 2.5 seconds:
showMessage('Your message')
Or by your own settings for type message 'Error' and timeout 4 seconds:
showMessage('Your message', type='error', timeout=4000)

python button combination to open a tkinter message box

im new topython 2.7 and want to know if it is possible to open a tkinter messagebox with a button combination on keyboard (Ctrl+alt+'something')
that pops up like an windows error message
import win32api
import time
import math
import Tkinter
import tkMessageBox
top = Tkinter.Tk()
def Message():
tkMessageBox.showinfo("Window", "Text")
for i in range(9000):
x = int(600+math.sin(math.pi*i/100)*500)
y = int(500+math.cos(i)*100)
win32api.SetCursorPos((x,y))
time.sleep(.01)

Yes, you can bind to control and alt characters. Bindings are fairly well documented. Here's one good source of information:
http://effbot.org/tkinterbook/tkinter-events-and-bindings.htm
As an example, to bind to ctrl-alt-x you would do this:
top.bind("<Control-Alt-x>", Message)
You can bind to a sequence of events by specifying the whole sequence. For example, if you wanted to implement a cheat code you could do something like this:
label.bind("<c><h><e><a><t>", Message)
For letters, "a" is the same as "<a>", so you can also do this:
label.bind("cheat", Message)
Here is a complete working example:
import Tkinter as tk
import tkMessageBox
def Message(event=None):
tkMessageBox.showinfo("Window", "Text")
def Cheat(event=None):
tkMessageBox.showinfo("Window", "Cheat Enabled!")
root = tk.Tk()
label = tk.Label(root, text="Press control-alt-m to see the messagebox\ntype 'cheat' to enable cheat.")
label.pack(fill="both", expand=True, padx=10, pady=100)
label.bind("<Control-Alt-x>", Message)
label.bind("<c><h><e><a><t>", Cheat)
label.focus_set()
root.mainloop()

If you want something like: Press button A, then press button B then open a Message box it is possible.
Do something like:
from Tkinter import *
import tkMessageBox
def change():
global switch
switch=True
def new_window():
if switch:
tkMessageBox.showinfo("Random name", "Correct combination")
else:
print "Not the correct order"
root = Tk()
switch = False
root.bind("<A>", change)
root.bind("<B>",new_window)
root.mainloop()
If you want more buttons then use an integer and increase it while using switches for the correct button order.
Note that you can bind key combinations as well with root.bind("<Shift-E>") for example
Edit: Now a and b keyboard button insted of tkinter buttons

Python: tkinter askyesno method opens an empty window

I use this to get yes/no from user but it opens an empty window:
from Tkinter import *
from tkMessageBox import *
if askyesno('Verify', 'Really quit?'):
print "ok"
And this empty window doesnt go away. How can I prevent this?
This won't work:
Tk().withdraw()
showinfo('OK', 'Select month')
print "line 677"
root = Tk()
root.title("Report month")
months = ["Jan","Feb","Mar"]
sel_list = []
print "line 682"
def get_sel():
sel_list.append(Lb1.curselection())
root.destroy()
def cancel():
root.destroy()
B = Button(root, text ="OK", command = get_sel)
C = Button(root, text ="Cancel", command = cancel)
Lb1 = Listbox(root, selectmode=SINGLE)
for i,j in enumerate(months):
Lb1.insert(i,j)
Lb1.pack()
B.pack()
C.pack()
print "line 702"
root.mainloop()
for i in sel_list[0]:
print months[int(i)]
return months[int(sel_list[0][0])]

Tkinter requires that a root window exist before you can create any other widgets, windows or dialogs. If you try to create a dialog before creating a root window, tkinter will automatically create the root window for you.
The solution is to explicitly create a root window, then withdraw it if you don't want it to be visible.
You should always create exactly one instance of Tk, and your program should be designed to exit when that window is destroyed.

Create root window explicitly, then withdraw.
from Tkinter import *
from tkMessageBox import *
Tk().withdraw()
askyesno('Verify', 'Really quit?')
Not beautiful solution, but it works.
UPDATE
Do not create the second Tk window.
from Tkinter import *
from tkMessageBox import *
root = Tk()
root.withdraw()
showinfo('OK', 'Please choose')
root.deiconify()
# Do not create another Tk window. reuse root.
root.title("Report month")
...