1 00:00:01,160 --> 00:00:02,500 Hello again, everyone. 2 00:00:02,860 --> 00:00:09,850 So we've been talking a lot about TypeScript, right, so it's why don't we get into something else 3 00:00:09,850 --> 00:00:11,800 called inheritance? 4 00:00:13,270 --> 00:00:21,280 So, as the name suggests, inheritance is the name of the transferred genetic characteristics. 5 00:00:22,670 --> 00:00:28,880 So I'll try to put it into context here and explain it briefly with an example, let's say that there 6 00:00:28,910 --> 00:00:35,340 are employees working in a particular workplace and the customers who shop here. 7 00:00:35,990 --> 00:00:41,210 So what customers and employees have in common is, well, they are a person. 8 00:00:42,940 --> 00:00:45,710 And a person has different features. 9 00:00:46,660 --> 00:00:53,710 So here we are creating a class where we can define common characteristics of people, so we create 10 00:00:53,710 --> 00:01:00,250 a new class for different features, but we extend this new class to the first class. 11 00:01:01,360 --> 00:01:04,480 Thus, we can use the first class features. 12 00:01:06,280 --> 00:01:11,860 So as we will see in practice, I'm first creating a person class in here, I'm. 13 00:01:16,940 --> 00:01:19,190 Writing a simple save method. 14 00:01:26,370 --> 00:01:31,150 Then I'll create a customer class and extend the person class. 15 00:01:31,320 --> 00:01:31,860 You follow. 16 00:01:39,440 --> 00:01:45,050 So that way, the customer class now has the features of this original class. 17 00:01:46,310 --> 00:01:49,580 So here again, I'll add a simple method. 18 00:01:53,380 --> 00:01:56,460 Now, I can create the employee class in the same way. 19 00:02:10,550 --> 00:02:19,490 All right, so we've created our classes, so now it's time to create a new object from each of these 20 00:02:19,490 --> 00:02:20,190 classes. 21 00:02:21,380 --> 00:02:26,300 So first I create an object from the person class and. 22 00:02:32,590 --> 00:02:38,620 Look here, when I put a dot behind the name, I can use the save method. 23 00:02:40,690 --> 00:02:42,640 Now, let's do the same to the customer class. 24 00:02:48,650 --> 00:02:56,610 And now, look, I can use two methods, both in the person class and in the customer class. 25 00:02:57,420 --> 00:02:59,480 Whoa, how can you do that? 26 00:03:00,020 --> 00:03:08,630 Well, we've stated that we can use its properties and methods by extending this class person. 27 00:03:08,630 --> 00:03:14,540 Class features were transferred to the customer class thanks to that the inheritance. 28 00:03:16,460 --> 00:03:20,300 OK, so now when we do the same operations in the third class. 29 00:03:26,360 --> 00:03:32,750 We can use these two methods again, both the methods specific to the class and the method that we will 30 00:03:32,750 --> 00:03:33,680 use in common. 31 00:03:35,080 --> 00:03:40,510 So as you can see, when we create a structure with common features, we do not have to write the same 32 00:03:40,510 --> 00:03:46,080 features on the time we collect common features in one classroom. 33 00:03:47,620 --> 00:03:55,660 Special features in other classes as our work becomes a lot easier when there's any change in the code 34 00:03:55,660 --> 00:03:56,080 editing. 35 00:03:58,250 --> 00:04:05,900 It's now before we finish up here, I do want to briefly introduce you to the idea of private and public 36 00:04:05,900 --> 00:04:13,910 access and how do we actually define it by a whole lot better if we continue on the first car that we 37 00:04:14,270 --> 00:04:15,680 wrote in a class. 38 00:04:16,790 --> 00:04:17,300 All right. 39 00:04:17,300 --> 00:04:22,040 So now, my friends, all the variables we've defined here are public just by default. 40 00:04:25,060 --> 00:04:28,210 And that's just so that we don't have to write public every time. 41 00:04:29,670 --> 00:04:31,290 So what a variable is public? 42 00:04:32,040 --> 00:04:38,550 Well, just as it implies, we're allowed to access that variable from pretty much anywhere. 43 00:04:39,870 --> 00:04:47,700 But if I come in here and write private and yeah, we'll make this very private now, see how we can't 44 00:04:47,700 --> 00:04:49,770 show this very well outside of this class. 45 00:04:55,080 --> 00:04:59,070 However, we can still use it inside the glass. 46 00:05:00,450 --> 00:05:04,800 So here we can only use a variable in that class when we make it private. 47 00:05:05,730 --> 00:05:06,120 All right. 48 00:05:07,730 --> 00:05:12,650 Let's have a look and see what happens when we use a private variable in the person class. 49 00:05:18,210 --> 00:05:20,160 So I'm using a private variable here. 50 00:05:20,400 --> 00:05:23,520 Well, I can use this variable in the customer class. 51 00:05:25,220 --> 00:05:32,210 No, I can't, because, as we said, this variable can only be used within the class in which it is 52 00:05:32,210 --> 00:05:32,900 defined. 53 00:05:33,710 --> 00:05:37,460 So if we define this variable as protected here. 54 00:05:41,970 --> 00:05:43,560 We can now do what we want. 55 00:05:45,290 --> 00:05:54,350 So protected access is pretty much the same logic as private, however, as you can see, it can be 56 00:05:54,350 --> 00:05:56,960 used in inheritance classes. 57 00:06:01,650 --> 00:06:07,470 We won't be able to use this variable outside as a public variable, you follow. 58 00:06:09,990 --> 00:06:15,090 All right, well, let me ask you this, how can we use a private variable outside the class? 59 00:06:16,440 --> 00:06:18,290 Well, I'm glad you bring that up. 60 00:06:19,540 --> 00:06:23,450 Because we've got to talk about getter and setter methods. 61 00:06:24,610 --> 00:06:26,800 All right, so let's have a look at the usage now. 62 00:06:27,790 --> 00:06:34,060 So I'm defining a private variable here and I define the get method that will return this variable. 63 00:06:46,600 --> 00:06:50,200 Then I write the set method that takes this variable. 64 00:07:07,390 --> 00:07:11,740 And now I give a value to this variable outside of this class. 65 00:07:15,220 --> 00:07:21,510 Now we can run these codes and see and here we can see the value that we return. 66 00:07:22,770 --> 00:07:29,400 So by creating the getting set methods of a private variable, we were able to use these methods outside 67 00:07:29,400 --> 00:07:30,130 of the class. 68 00:07:31,140 --> 00:07:31,860 What do you think? 69 00:07:32,820 --> 00:07:35,990 So sure enough, my friends, indeed this classroom is enough. 70 00:07:36,780 --> 00:07:39,190 So in our next lesson, we're going to talk about interface. 71 00:07:39,990 --> 00:07:40,680 I'll see you then. 72 00:07:41,280 --> 00:07:42,000 Bye for now.