Polling

All right so to do my polling, I'm actually gonna make a new method and 0:00 I'm gonna call it update. 0:03 And let's just print updated. 0:06 All right and 0:09 then we want to make sure that our update method gets called every second. 0:10 And what's cool is that our global app, the thing we called master, 0:17 in here self.master, I know we called it root on the outside. 0:22 It has a method called after and 0:25 it will fire off after a certain number of milliseconds. 0:30 So let's use that. 0:34 So we'll say self.master.after and then, 0:35 we're supposed to find the number of milliseconds. 0:40 So 1000 milliseconds is one second. 0:42 And then we want that to run self.update. 0:46 Okay, so we had 1000 milliseconds, or one second, and then we run update again. 0:50 All right, so after all the stuff gets built, then we run self.update. 0:55 Okay, so now run. 1:02 And every second, the window is off screen. 1:07 Every second, it prints out updated. 1:09 Cool so, that's great. 1:12 We know that works. 1:15 In this method, is where I want to decrement the timer. 1:16 So first let's get how much time is left. 1:20 And we'll say time_left = self.time_left.get() so 1:24 we're just holding onto it. 1:29 That's just easier to type than self.time_left all the time. 1:30 So for running, and there's time left, so if self.running and 1:34 time_left so time left isn't zero, 1:40 then we want to take one second off of the number. 1:45 So, we'll do self.time and left.set to time left -1. 1:49 Otherwise, so 1:55 else, we just wanna set running to false and then reset the buttons. 1:58 So, we can just call self.stop_timer. 2:02 Because that does what we want. 2:07 It turns running to false and resets the buttons. 2:08 So if we're running and there's time left. 2:12 Let's take a second off the time left number. 2:14 Otherwise let's just call our stop timer method to reset the buttons and 2:16 turn off the running variable. 2:20 All right so now we need to make sure that our timer, like we haven't even been 2:22 showing the timer label at all, it's just been blank because there's no text. 2:26 So we need to make sure that updates with how much time is actually left. 2:30 So we should tell the variable that controls the text of the timer label 2:35 to watch for changes. 2:39 And then when it changes to redraw the label. 2:41 So now we're already drawing the label right here in our build timer method. 2:44 We need to tell the method, since we're gonna, so 2:51 first of all let's come up here, let's do this one step at a time. 2:54 All right so here is where we made our timer text variable. 2:58 So this is the text that we display. 3:06 So we wanna tell this text that whenever 3:12 it gets updated to go do some of it. 3:17 All right, so w means whenever this was written to. 3:22 Then we wanna call self.build_timer. 3:27 Okay, so go down here to self.build_timer. 3:31 So build_timer is now gonna get called by itself. 3:35 But it's also gonna get called whenever that trace fires. 3:39 And when that trace fires, it sends some more information as well. 3:42 So we have to accept args. 3:46 We're not going to use these args at all we don't care about them but 3:49 we have to except them because python has the rule that like you have to know 3:54 how many variables are coming in. 3:57 So anytime the timer updates were going to call build timer. 4:00 Any time the timer text updates okay. 4:04 So, let's go update that label. 4:08 So here in update we are going to the minutes and seconds that are left. 4:11 So I'm actually going to make another method here. 4:20 I'm gonna call it minutes_seconds. 4:24 And it's going to take seconds which is a going to be a number of seconds. 4:27 And I want to return the minutes which should be the int version 4:31 of seconds divided by 60. 4:35 I could also do seconds // 60 which will do int division. 4:37 And then I want the int version of seconds modulo 60. 4:43 Modulo gives us effectively the remainder. 4:47 So we're gonna return minutes. 4:50 And we're gonna return seconds. 4:52 All right, so down here, inside the time left, let's do minutes, 4:55 seconds = self.minutes_second. 5:00 And we're gonna pass in (time_left) cuz that's how much time is left, right? 5:04 And then we're gonna do self.timer_text.set(). 5:09 And I want to set this timer text to something. 5:13 Normally we would do like this because we want minutes and seconds but 5:17 we want to format this. 5:19 So I want zeros padded out to two digits. 5:20 And then again zeros added out to two digits. 5:25 There we go. 5:30 And then I call format with minutes and seconds. 5:31 All right and then we need to do this again. 5:34 Let's just copy this thing here all over again. 5:40 End it before the timers stop. 5:45 But instead of time left here, we're going to do it with 5:47 DEFAULT_GAP and then we get that same text in there. 5:51 Okay, this could probably be optimized if we wanted to move it in 5:59 out of the if else. 6:03 But for now let's just not worry about it, okay. 6:04 [LAUGH] So that should do the work that we needed it to do. 6:07 And this should make our timer count down. 6:10 Let's see, let's run this. 6:12 Bring one over here, let's hit Start. 6:16 What do you know? 6:21 Look at that, it's counting down by seconds, more or less. 6:22 All right let's test what happens when this runs out. 6:26 But to do that, I don't wanna wait 25 minutes. 6:32 So let's do a new default gap and we'll just say, five seconds. 6:35 All right, so run this again. 6:39 And so all right, we've got five seconds left, hit start, four, three, two, one. 6:46 Boop, and it, hey, look at that. 6:54 It reset. 6:55 The stop button is effectively clicked, gonna start, gonna go back to five. 6:56 So that's cool, that's awesome. 7:00 Now, let's see about setting up an alert. 7:01