python - Tkinter loop function -

i new gui programming , i'm trying python program work. correct way call function start() updates 2 canvases. code looks this.

from tkinter import * class tkinter_test(frame):    def __init__(self,parent):        frame.__init__(self,parent)        self.parent = parent        self.initui()     user_reply = 0      def accept(self):        self.user_reply = 1    def decline(self):        self.user_reply = 2     def initui(self):        btnframe = frame (self.parent)        btnframe.place(y=450, x=20)         canvasframe = frame(self.parent)        canvasframe.place(y = 200)        canvas_1 = canvas(canvasframe, width = "220", height ="200")        canvas_2 = canvas(canvasframe, width = "220", height ="200")        canvas_1.pack(side = left)        canvas_2.pack(side = right)           textfield_1 = canvas_1.create_text(30,50,anchor = 'w', font =("helvetica", 17))        textfield_2 = canvas_2.create_text(30,50,anchor = 'w', font =("helvetica", 17))        accept = button(btnframe, text="friends!", width=25, command = self.accept)        decline = button(btnframe, text="not friends...", width=25, command = self.decline)        accept.pack(side = left)        decline.pack(side = right)     def ask_user(self,friend_1,friend_2):        timer = 0;         while(timer == 0):            if(self.user_reply == 1):                print friend_1 + " , " + friend_2 + " friends!"                self.user_reply = 0                timer = 1;            elif(user_reply == 2):                print friend_1 + " , " + friend_2 + " not friends..."                self.user_reply = 0                timer = 1     def start(self):        listofpeople = ["john","tiffany","leo","tomas","stacy","robin","carl"]        listofpeople_2 = ["george","jasmin","rosa","connor","valerie","james","bob"]        friend_1 in listofpeople:            friend_2 in listofpeople_2:                ask_user(friend_1,friend_2)        print "finished"  def main():     root = tk()     root.geometry("500x550")     root.wm_title("tkinter test")     app = tkinter_test(root)     root.mainloop()  if __name__ == '__main__': main() 

i use in ask_user updates textfield_1 , 2. textfield_1.itemconfigure(text = friend_1) , prefer not use threads. thank you.

it takes different mindset event-driven programming, , can bit frustrating , bewildering @ first. suggest take @ code in high-scoring tkinter answers on stack overflow, , experiment it, making small changes , see happens. become more familiar it will begin make sense. :)

i don't know why want frame , canvas objects, i've simplified gui use single frame, "borrowing" bryan oakley's template this answer. rather using canvas text items display friend names use simple label widgets.

instead of hard-coding friends lists gui class pass them in tuple gui constructor keyword argument, friendlists. have remove argument kwargs before passing kwargs on frame.__init__ method, since method treats keyword args doesn't recognize errors.

i create generator expression self.pairs uses double for loop yield pairs of friend names. calling next(self.pairs) gives next pair of friend names.

when button pressed test_friends method called reply arg of true or false, depending on whether "friends!" or "not friends." button pressed.

test_friends prints information current pair of friends , calls set_friends method set names of next pair of friends in labels. if there no pairs left, program exits.

import tkinter tk  class mainapplication(tk.frame):     def __init__(self, parent, *args, **kwargs):         # extract friend lists keyword args          friends1, friends2 = kwargs['friendlists']         del kwargs['friendlists']          tk.frame.__init__(self, parent, *args, **kwargs)         self.parent = parent          # generator yields pairs of people friends lists         self.pairs = ((u, v) u in friends1 v in friends2)          # pair of labels display names         self.friend1 = tk.stringvar()         tk.label(self, textvariable=self.friend1).grid(row=0, column=0)          self.friend2 = tk.stringvar()         tk.label(self, textvariable=self.friend2).grid(row=0, column=1)          # set first pair of names         self.set_friends()          cmd = lambda: self.test_friends(true)         b = tk.button(self, text="friends!", width=25, command=cmd)         b.grid(row=1, column=0)          cmd = lambda: self.test_friends(false)         b = tk.button(self, text="not friends.", width=25, command=cmd)         b.grid(row=1, column=1)      def set_friends(self):         # set next pair of names         f1, f2 = next(self.pairs)         self.friend1.set(f1)         self.friend2.set(f2)      def test_friends(self, reply):         f1, f2 =  self.friend1.get(), self.friend2.get()         reply = (' not ', ' ')[reply]         print '%s , %s are%sfriends' % (f1, f2, reply)         try:             self.set_friends()         except stopiteration:             # no more pairs             print 'finished!'             self.parent.destroy()   def main():     people_1 = [         "john",          "tiffany",          "leo",          "tomas",          #"stacy",          #"robin",          #"carl",     ]      people_2 = [         "george",          "jasmin",          "rosa",          #"connor",          #"valerie",          #"james",          #"bob",     ]      root = tk.tk()     root.wm_title("friend info")     app = mainapplication(root, friendlists=(people_1, people_2))     app.pack()     root.mainloop()  if __name__ == "__main__":     main()