1
00:00:00,330 --> 00:00:04,360
Oh, boy, there's some code on the screen and it looks terribly confusing.

2
00:00:04,800 --> 00:00:11,160
This is an example of a really convoluted, complicated function that you would never write, but it'll

3
00:00:11,160 --> 00:00:12,900
be good for exercise purposes.

4
00:00:13,320 --> 00:00:18,870
And we're talking specifically about this right here called nonlocal.

5
00:00:19,140 --> 00:00:22,520
It's actually a new keyword in Python three.

6
00:00:22,800 --> 00:00:27,210
And as you can see, my Reppel doesn't even notice it.

7
00:00:27,210 --> 00:00:30,210
So it doesn't even highlighted in blue because it is a new feature.

8
00:00:30,570 --> 00:00:33,390
But I do want to talk to you about it and let you know what it does.

9
00:00:34,330 --> 00:00:40,960
The nonlocal key keyword is used to refer to this part, this parent local.

10
00:00:41,200 --> 00:00:48,310
It's a way for us to say, hey, I want to use a variable that is not a global variable, but is outside

11
00:00:48,310 --> 00:00:50,380
of the scope of my function.

12
00:00:51,440 --> 00:00:58,460
So based on that definition, try and pause the video and see what this function might do, I'll run

13
00:00:58,460 --> 00:01:03,170
it right now and then go through the code if I click run.

14
00:01:04,560 --> 00:01:06,030
This is what we get.

15
00:01:07,880 --> 00:01:09,320
So let's talk about this.

16
00:01:10,750 --> 00:01:15,050
We have an outer function and then we call the outer function.

17
00:01:15,100 --> 00:01:22,000
So the Python interpreter is going to go and say, all right, we have an X variable that is local to

18
00:01:22,000 --> 00:01:23,980
the outer function.

19
00:01:24,610 --> 00:01:28,870
And then inside of here, we going to define an inner function, another function.

20
00:01:29,320 --> 00:01:34,930
And in here, before we even call that, we jumped in line nine and say, all right, call inner function.

21
00:01:35,230 --> 00:01:40,390
We come back and we say, hey, line five, I want to use nonlocal X.

22
00:01:41,300 --> 00:01:41,450
Hmm.

23
00:01:41,740 --> 00:01:42,470
What does that mean?

24
00:01:42,610 --> 00:01:47,890
Well, I want to use this X variable because it's nonlocal.

25
00:01:47,890 --> 00:01:51,160
That is, I don't want to create a new X variable.

26
00:01:51,310 --> 00:02:00,010
I want to jump up the scope to my parents, scope my parent local and grab whatever you find in there.

27
00:02:00,340 --> 00:02:03,310
As long as it's not global variable any parent will do.

28
00:02:03,550 --> 00:02:04,980
I want to grab that nonlocal.

29
00:02:04,990 --> 00:02:08,720
So now this X is referring to the outer function here.

30
00:02:09,490 --> 00:02:17,260
So when we say X equals nonlocal, we're assigning this new string.

31
00:02:18,940 --> 00:02:26,290
And replacing this local so that when we print interacts, we get nonlocal, but also when we print

32
00:02:26,290 --> 00:02:32,470
the outer X, we've modified this outer scope with the nonlocal keyword.

33
00:02:32,530 --> 00:02:34,980
So that becomes nonlocal as well.

34
00:02:35,650 --> 00:02:39,310
If I remove this line and let's comment it out and I click run.

35
00:02:40,490 --> 00:02:47,540
You see the difference now we have the inner nonlocal, but then the outer local hasn't been modified

36
00:02:47,540 --> 00:02:49,580
because this is a new variable.

37
00:02:51,090 --> 00:02:57,450
Again, I argue that this actually makes your code more complicated than it needs to be.

38
00:02:58,320 --> 00:03:04,200
So there are special cases where you might want to use this, but if you can try to make your code predictable,

39
00:03:04,200 --> 00:03:11,310
where you can avoid using things like nonlocal and global, mind you, they are there for a reason because

40
00:03:11,310 --> 00:03:13,830
they are useful in some situations.

41
00:03:14,310 --> 00:03:19,680
With that said, keep in mind, make your code predictable, make your code clean, and I'll see you

42
00:03:19,680 --> 00:03:20,430
in the next video.