Stop infinite function in tkinter - python-3.x

Question

I have put together a GUI which searches for a specific subject matter in your email within a while loop and continues to do so until it finds an unread message with that subject. Once it finds that email, it does some other functions and when all those functions are complete, it loops back to the beginning and searches once again for an unread message containing that subject. I am wanting to implement a "stop" button which will allow the user to break out of this infinite loop of search the inbox but I've had no success and am unsure on how to tackle this problem. I have tried searching for comparable examples but have been unable to implement them to my specific situation. I've truncated the code as much as possible to still allow for interpretation.
class App(tk.Frame):
def __init__(self, parent, *args, **kwargs):
tk.Frame.__init__(self, parent, *args, **kwargs)
self.parent = parent
self.desktop_path = os.path.join(os.environ['USERPROFILE'],'Desktop')
#create labelframe for directory and browse button
label_frame = tk.LabelFrame(self, text=" Search Inbox:")
label_frame.grid(row=1, columnspan=15, sticky='WE', padx=5, pady=5, ipadx=5, ipady=5)
#create label frame for send report and button
label_frame2 = tk.LabelFrame(self, text=" Interrupt Search:")
label_frame2.grid(row=2, columnspan=15, sticky='WE', padx=5, pady=5, ipadx=5, ipady=5)
#create label frame for send report and button
self.label_frame3 = tk.LabelFrame(self, text=" Totals:")
self.label_frame3.grid(row=3, columnspan=15, sticky='WE', padx=5, pady=5, ipadx=5, ipady=5)
#create browse button and place on grid
label_frame.button = ttk.Button(label_frame, text="Start",command=self.start, width=8)
label_frame.button.grid(row=4, column=7, sticky="EW", padx=100, ipadx=10)
#create send report button and place on grid
label_frame2.button = ttk.Button(label_frame2, text='Stop', command=self.stop, width=8)
label_frame2.button.grid(row=4, column=7, sticky='EW', padx=100, ipadx=10)
self.label_frame3.entry = tk.Entry(self.label_frame3)
self.label_frame3.entry.grid(row=4, column=7, stick='W', padx=50, ipadx=25)
def SaveAttachments(self, subject='subject matter goes here'):
#create outlook application object
outlook = win32com.client.Dispatch("Outlook.Application").GetNamespace("MAPI")
inbox = outlook.GetDefaultFolder(6) #create an inbox object
messages = inbox.Items #create a message object
try:
inbox.Folders.Add('Extracts') #create folder in inbox, if already exsists, nothing happens.
except:
pass
#iterate through messages to find message that matches subject and is unread
for message in messages:
if message.Subject == subject and message.Unread:
attachments = message.Attachments
attachment = attachments.Item(1)
for attachment in message.Attachments:
if not os.path.isdir(self.desktop_path): #check if the path exsists, and if it doesn't, create it
os.makedirs(self.desktop_path)
attachment.SaveAsFile(os.path.join(self.desktop_path, str(attachment)))
if message.Subject == subject and message.Unread:
message.Unread = False #change message status from unread to read
message.Move(inbox.Folders('Extracts')) #move read messages to Extracts Folder
#print(attachment)
break
else:
attachment = None
return os.path.join(self.desktop_path, str(attachment))
def start(self, event=None):
self.cancel_id = None
self.main()
def main(self, event=None):
variable = True
while variable:
file = self.SaveAttachments()
if 'None' not in file:
variable = False
self.CreatePivots(file)
self.CreateExcel()
self.SendEmail()
self.label_frame3.entry.delete(0, 'end')
self.label_frame3.entry.insert(0, f'{self.table.iloc[-1,0]}')
self.cancel_id = self.label_frame3.entry.after(1000, self.main)
variable = True
def stop(self, event=None):
if self.cancel_id is not None:
self.label_frame3.entry.after_cancel(self.cancel_id)
self.cancel_id = None

Answer 1

You should do something liket this using threading.
This is the simplest example that comes to my mind for reproduce the behaviour that you want
import tkinter as tk
import threading as th
import time
class App:
def __init__(self):
self.root = tk.Tk()
self.run = True
self.counter = 0
def build(self):
self.counter_label = tk.Label(text=self.counter)
self.counter_label.pack()
self.stop_button = tk.Button(text='stop', command=self.stop_counter)
self.stop_button.pack()
def start_counter(self):
while self.run:
self.counter += 1
self.counter_label.configure(text=self.counter)
time.sleep(1)
def run_counter(self):
self.my_thread = th.Thread(target=self.start_counter) # create new thread that runs the self.start_counter() function
self.my_thread.start() # start the threading
def stop_counter(self):
self.counter_label.configure(text="counter stopped")
self.run = False # set the variable to false so that the while loop inside the threading stops
self.my_thread.join() # this destoy the created threading
def start_loop(self):
self.root.mainloop() # starts the tkinter mainloop
app = App()
app.build()
app.run_counter()
app.start_loop()
By the way, its better to call the variables with a significant name that will help you remind for what they are used.