WEBVTT 00:00.500 --> 00:03.890 I will call you back again to another video lecture in PHP. 00:03.890 --> 00:09.860 And in this video lecture we go ahead and look at inheritance in PHP. 00:16.940 --> 00:17.420 All right. 00:17.420 --> 00:24.560 So inheritance is uh, normal, like when we had the property of your parents or someone inherits your 00:24.560 --> 00:25.340 own property. 00:25.340 --> 00:29.750 So inheritance we have a class and also have a child class. 00:29.750 --> 00:34.400 So the parent class is a class that we inherit the property from. 00:34.400 --> 00:38.750 When a child class is one that inherits the property of the parent class. 00:38.870 --> 00:42.740 Now let's go ahead and say we have a class called Science Teacher. 00:42.740 --> 00:50.390 And this class we have the functions and we have function assays, teach physics, teach chemistry and 00:50.390 --> 00:51.410 teach biology. 00:51.410 --> 00:53.540 And another function teach chemistry. 00:53.570 --> 00:58.460 This teacher teaches the chemistry and another function teach physics. 00:58.460 --> 01:02.660 This teacher teaches physics and then another function teach biology. 01:02.660 --> 01:04.670 This teacher teaches biology. 01:04.700 --> 01:06.940 Now this is the function of this tissue. 01:06.970 --> 01:10.870 The function is how is physics chemistry and biology. 01:10.870 --> 01:12.520 And that is the science teacher. 01:12.550 --> 01:14.470 Now we have a child class. 01:14.500 --> 01:17.140 Let's go ahead and create a child class but without name. 01:17.140 --> 01:19.660 If we go ahead and uh print that out. 01:19.660 --> 01:24.880 So we have this declared right in here and uh, we are going to print that out. 01:24.910 --> 01:26.830 Go ahead and refresh and let's check it out. 01:26.830 --> 01:29.800 So we try to print out Teach chemistry. 01:29.800 --> 01:31.510 And this teacher teaches chemistry. 01:31.540 --> 01:34.060 Now let's go ahead and create a child class. 01:34.060 --> 01:36.910 And I'm going to say class. 01:36.910 --> 01:40.930 And let me go ahead and call that to be general teacher. 01:40.930 --> 01:51.820 So this teacher we actually teach everything, but uh, it's not a teacher but um, adds and uh, it's 01:51.820 --> 01:56.530 going to teach but science and adds, that is what this teacher needs to do. 01:56.530 --> 02:02.200 So if this teacher is going to do whatever that's the science teacher does. 02:02.200 --> 02:05.590 So whatever the science teacher does, this teacher will actually do that. 02:05.590 --> 02:09.220 So let's go ahead and see this general teacher we have right in here. 02:09.250 --> 02:12.290 We are now going to specify anything right in here. 02:12.320 --> 02:20.780 Now, what I'm going to do is I'm going to say this class teacher will now extend. 02:20.780 --> 02:29.030 So it extends to the science teacher which is the parent class. 02:29.030 --> 02:30.680 And now we have done that. 02:30.680 --> 02:33.110 We can now go down here. 02:33.140 --> 02:35.420 Let's go ahead and declare this. 02:35.420 --> 02:50.120 And I'm going to say this is a general teacher is equal to new general teacher. 02:50.120 --> 02:55.550 So when I create the object of this teacher right in here, so just created the object of this teacher 02:55.550 --> 02:58.190 and the the square head and print that out. 02:58.190 --> 03:00.890 So go ahead and say general. 03:03.200 --> 03:07.550 General teacher I mean greater than. 03:07.880 --> 03:12.500 And let me say it's going to teach um chemistry as well. 03:12.530 --> 03:15.530 So go ahead and say it teaches both chemistry. 03:15.550 --> 03:16.960 And let's go ahead and say that. 03:16.960 --> 03:19.660 So these teach chemistry. 03:19.690 --> 03:23.650 We supposed to also put this as a function because this is a function. 03:23.680 --> 03:26.950 Go ahead and put this function right in here and put a semicolon. 03:26.950 --> 03:28.150 So that is an error. 03:28.150 --> 03:29.500 But it actually is located. 03:29.500 --> 03:34.510 So go ahead and copy whatever you have right in here and then paste that here. 03:34.720 --> 03:36.880 So this and let's check it out. 03:36.880 --> 03:41.260 So this teacher teaches chemistry and this teacher teaches chemistry. 03:41.260 --> 03:45.760 And you can see I just created this class called General Teacher. 03:45.760 --> 03:49.540 And it extends to the current class science teacher. 03:49.540 --> 03:52.780 And we did not display anything right inside there. 03:52.810 --> 03:54.580 We didn't declare anything. 03:54.580 --> 03:57.340 We only use that keyword extends. 03:57.340 --> 04:04.990 And that's inherits the property of this, uh, science teacher, which is the parent class. 04:05.200 --> 04:08.080 So you can see that this really works fine. 04:08.740 --> 04:14.560 So we can actually go ahead and give this a class teacher, the general teacher, a function where we 04:14.560 --> 04:17.530 see we go ahead and create a function. 04:18.370 --> 04:26.510 And let's say that this teacher helm teach history because he is a general teacher. 04:26.510 --> 04:32.540 It can actually do everything the science teacher does and actually also do any other one it wants. 04:32.540 --> 04:34.580 So let's say it teaches history. 04:34.700 --> 04:38.600 And uh, inside here we'll go ahead and say it. 04:38.660 --> 04:48.680 So this teacher teaches history. 04:48.800 --> 04:52.610 So this teacher teaches history as well because he's a general teacher. 04:52.610 --> 04:54.620 And go ahead and apply semicolon at the end. 04:54.620 --> 04:59.510 And uh, let's go right in here and uh, paste this out. 04:59.540 --> 05:09.500 Let's go ahead and say go ahead and copy this teaches history and change it out to, uh, the chemistry. 05:09.530 --> 05:12.140 Let's go ahead and save this and refresh this. 05:12.170 --> 05:14.540 This teacher teaches history. 05:15.650 --> 05:20.840 So you can see that this teacher actually does whatever the current teacher does. 05:20.870 --> 05:25.930 And the current class, I mean, this child teach class. 05:25.930 --> 05:32.260 The child class, which is the general teacher, does everything that the parent class, which is the 05:32.260 --> 05:35.410 science teacher does, and it can actually do more. 05:35.830 --> 05:37.300 That is very interesting. 05:37.300 --> 05:42.970 Path of inheritance is a very interesting part of inheritance and is really very, very good. 05:42.970 --> 05:47.410 Now I'm going to another thing I will also show you, which is called overriding. 05:47.410 --> 05:51.460 So it can actually override the parent teacher. 05:51.640 --> 05:57.790 Let's say we have a teacher's biology inside here. 05:58.000 --> 06:00.430 Then we go ahead and say this is teachers biology. 06:02.950 --> 06:06.040 So if I go ahead and copy everything right in here. 06:08.620 --> 06:10.360 I will go ahead and press down right here. 06:10.600 --> 06:15.070 And uh, this is teachers biology. 06:18.580 --> 06:25.600 Now I will go ahead and say this teacher, instead of teaching biology, I will say this teacher. 06:25.630 --> 06:27.220 Teacher is a government. 06:37.170 --> 06:39.810 Okay, so this is our government. 06:40.410 --> 06:41.250 All right. 06:43.650 --> 06:48.420 And now if we go right in here and print out, let's copy this. 06:48.450 --> 06:54.840 The class, the function, uh, teaches biology. 06:54.840 --> 06:56.790 And we go over here and put choose biology. 06:56.820 --> 06:59.070 And let's save this and refresh. 06:59.460 --> 07:04.620 You can now see that the first one says teaches biology. 07:04.650 --> 07:06.720 This teacher teaches biology. 07:06.720 --> 07:11.130 And the second one says this teacher teaches government. 07:11.160 --> 07:11.760 It's over. 07:11.760 --> 07:12.240 Right. 07:12.270 --> 07:15.930 What it has in the first one, it's no longer printed out. 07:15.960 --> 07:17.280 What it has. 07:18.120 --> 07:20.130 Okay, what if you go and comment? 07:20.130 --> 07:26.790 If you comment this and say teaches biology is going to print out teaches, but let's go ahead and do 07:26.790 --> 07:26.940 that. 07:26.940 --> 07:29.250 So you see that I'll go ahead and cut off this. 07:29.250 --> 07:31.080 I've cut it off and I'm going to save it. 07:31.080 --> 07:32.670 And now let's go ahead and refresh. 07:32.670 --> 07:38.350 And you can see teacher teaches biology, and that is what is supposed to print what. 07:38.350 --> 07:42.400 We override that and then went ahead and print our own. 07:42.400 --> 07:43.810 So I have put it back again. 07:43.810 --> 07:50.140 And if I refresh, I see this teacher teaches biology and that is called override. 07:50.980 --> 07:59.800 So if the child class, which inherited the properties of the parent class, can actually override that 07:59.800 --> 08:06.700 property, some of the properties it gets from the Paris and do more and even do more with what it has. 08:07.120 --> 08:13.870 So that is very, very interesting aspect of uh, inheritance in PHP. 08:13.900 --> 08:16.600 So go ahead and put it down. 08:16.630 --> 08:21.850 Try as much as possible to play around with it because inheritance is being tossed with practical example. 08:21.850 --> 08:24.070 And that is why we take this step by step. 08:24.070 --> 08:29.950 So I believe at the end you go ahead and understand what inheritance is all about. 08:29.950 --> 08:32.740 So try this and I have a question. 08:32.740 --> 08:36.760 Use the question and answer section and I'm going to get back to you as soon as possible. 08:36.790 --> 08:37.690 Thank you so much. 08:37.690 --> 08:40.630 And I'm going to see you in the next video lecture.