WEBVTT 0 00:00.290 --> 00:07.460 Throughout all of yesterday, we've been using other people's Classes, and we said that a class is 1 00:07.460 --> 00:12.320 simply just a Blueprint for creating an eventual object. 2 00:12.350 --> 00:17.660 In this lesson, we're going to talk about how we can create our own classes. 3 00:17.660 --> 00:23.030 So our own blueprints, which we can use to create our own objects. 4 00:23.630 --> 00:28.280 Now let's go ahead and create our own custom classes in code. 5 00:28.340 --> 00:33.980 Go ahead and create a new project and we're going to name it day-17-start. 6 00:34.250 --> 00:35.960 And then hit create. 7 00:36.440 --> 00:43.280 And again, as always, once you've created your project, it's time to create your first file, which 8 00:43.280 --> 00:44.900 we're going to name main.py. 9 00:44.900 --> 00:49.790 And then we can collapse our project sidebar and focus on the code. 10 00:50.720 --> 00:53.030 So how do we create a class? 11 00:53.240 --> 00:55.770 The syntax looks very simple. 12 00:55.770 --> 01:01.590 You have the 'class' keyword followed by the name of your class, and then a semicolon. 13 01:01.590 --> 01:07.110 And then all of the code that's in your class will follow this and it will be indented. 14 01:07.230 --> 01:10.260 Let's create our very first class in Python. 15 01:10.350 --> 01:17.430 As I mentioned, the way that we would create a class is first by using the 'class' keyword, and then 16 01:17.430 --> 01:19.650 we get to give our class a name. 17 01:19.650 --> 01:27.000 Let's say that we're building a website, and we need a class to model our website's users. 18 01:27.000 --> 01:34.770 So this class is basically going to be the blueprint to represent what our users have and what they 19 01:34.770 --> 01:36.480 can do on our website. 20 01:36.480 --> 01:38.880 So let's call our class, User, 21 01:38.880 --> 01:43.950 and then we finish this declaration with a semicolon as usual. 22 01:44.130 --> 01:51.160 And everything else that's going to go inside this class is going to need to be indented after the semicolon. 23 01:51.250 --> 01:54.640 Let's start out with a completely empty class. 24 01:54.670 --> 01:58.810 Our User class is going to do absolutely nothing for now. 25 01:58.810 --> 02:05.290 However, because I've created my blueprint, I can already use it to create my first User object. 26 02:05.350 --> 02:12.370 So let's say I wanted to create a user_1, and I'm going to create it using that class which notice 27 02:12.400 --> 02:14.560 it's now being recognized by PyCharm, 28 02:14.560 --> 02:16.990 and it's got the C symbol next to it. 29 02:16.990 --> 02:23.140 And of course to initialize an object from a class we have to add the parentheses at the end. 30 02:23.290 --> 02:27.850 Now we get an error here because there's an indent expected. 31 02:27.850 --> 02:34.330 So basically Python doesn't like it when you create something like a class or when you create something 32 02:34.330 --> 02:42.050 like a function and you have a semicolon, but you don't have anything inside that function or class. 33 02:42.050 --> 02:48.230 For example, if I just immediately wanted to print("hello"), afterwards, I get exactly the same error, 34 02:48.230 --> 02:49.520 Indent Expected. 35 02:49.520 --> 02:55.340 It's expecting this a function that you've created, or this class you've just created to have some 36 02:55.340 --> 02:59.060 sort of content before you go ahead and do something else. 37 02:59.180 --> 03:01.010 So how can we fix this? 38 03:01.010 --> 03:06.050 Well, if we actually really want to leave this function or this class empty, we can use a keyword 39 03:06.050 --> 03:07.310 which is 'pass'. 40 03:07.310 --> 03:10.100 And all it does is it just passes. 41 03:10.100 --> 03:12.170 It says, I don't want to have a go right now. 42 03:12.170 --> 03:14.840 Just continue to the next line of code. 43 03:14.840 --> 03:21.410 And this gets rid of our errors both in the function declaration, as well as in our class declaration. 44 03:21.590 --> 03:26.850 We've now essentially completed the first step towards creating our custom classes, which is writing 45 03:26.850 --> 03:32.610 the declaration, and then building an object called user_1 out of that class. 46 03:32.610 --> 03:36.330 And we've also seen how to name classes in Python. 47 03:36.330 --> 03:41.880 Now, the name of the class should have the first letter of every word capitalized, 48 03:41.880 --> 03:48.390 and this particular style of naming in programming is known as PascalCase. 49 03:48.390 --> 03:54.960 So if you think of Blaise Pascal as a person, then we know that everybody's name, every person's name, 50 03:54.960 --> 04:01.800 has the first letter capitalized and also the first letter of their surname or their middle name, and 51 04:01.800 --> 04:04.260 basically every subsequent name capitalized. 52 04:04.290 --> 04:09.600 Now, this is different from another type of casing which you may have come across, which is called 53 04:09.600 --> 04:10.620 camelCasing. 54 04:10.620 --> 04:17.680 And camel casing is only different from pascal case because the first word is lowercase, but every 55 04:17.680 --> 04:23.590 subsequent word has its first letter capitalized in exactly the same way as pascal case. 56 04:23.620 --> 04:29.260 And finally, we've also come across snake_case, where all the words are lowercase, but they're separated 57 04:29.260 --> 04:30.550 by an underscore. 58 04:31.180 --> 04:34.510 In Python programming, you won't see a lot of camel casing. 59 04:34.510 --> 04:40.810 You will see pascal case being used for the class names, snake_case being used pretty much to name 60 04:40.810 --> 04:42.070 everything else.