WEBVTT 00:00.450 --> 00:08.400 High in this session, we will discuss about polymorphism, so we have known that Wii functions can 00:08.400 --> 00:11.010 take different arguments. 00:11.340 --> 00:16.190 Methods belong to the object they act on, right. 00:16.470 --> 00:23.690 So we have methods which act on top of different object. 00:23.880 --> 00:28.830 So when we create a class, the class will contain different functions. 00:28.830 --> 00:32.610 And only these functions are called methods. 00:32.850 --> 00:36.910 And these methods will be working on the objects. 00:37.410 --> 00:37.750 Right. 00:37.980 --> 00:44.430 Whatever task I will be doing, whatever task my method will be performing, that task will be performed 00:44.430 --> 00:46.530 on top of my object. 00:46.920 --> 00:56.610 OK, now in Python polymorphism refers to the way in which different object classes can share the same 00:56.610 --> 01:06.930 method name and those methods can be called from the same place, even though a variety of different 01:06.930 --> 01:09.150 objects might be Boston. 01:09.780 --> 01:17.760 OK, so I can barson different types of object and my method can be called from the same place so I 01:17.760 --> 01:24.330 can have the same method acting differently for different types of object. 01:24.810 --> 01:27.290 OK, so how do we explain that. 01:27.300 --> 01:36.570 So basically polymorphism is a property of an object which allows it to take multiple form. 01:36.870 --> 01:44.130 OK, so when an object can take multiple forms and when we can work on different forms of an object 01:44.130 --> 01:52.200 that is called polymorphism, so it allows us to define same method in different classes so I can have 01:52.260 --> 01:53.470 the same method. 01:53.520 --> 02:03.920 Let's say I can have the same method as speak, OK, and this week can be present in case of dog also 02:03.930 --> 02:05.510 and in case of Catalyser. 02:05.940 --> 02:09.940 But how the output comes out to be would be different. 02:10.170 --> 02:14.150 So a dog would say, Wolf, while a dog would say meow. 02:14.340 --> 02:16.710 So those are the differences. 02:16.740 --> 02:24.830 So I have the same method speak, but we acted differently in case depending on if I'm calling in dog 02:24.840 --> 02:27.270 object or I'm calling the cat object. 02:28.300 --> 02:28.680 Right. 02:29.010 --> 02:34.860 So this is also known as method overriding the veto override, a particular method. 02:34.860 --> 02:36.900 We change how a method works. 02:37.450 --> 02:43.640 OK, now an example of this would be so we use GPS for navigating around. 02:43.890 --> 02:50.460 So when we come across many different routes for same destination, depending on the traffic from programming 02:50.460 --> 02:56.630 point of view, this is called polymorphism basically suggests us different route. 02:56.650 --> 02:58.500 So that is called polymorphism. 02:58.500 --> 03:02.790 So when same thing and have different solutions, which is called polymorphism. 03:03.160 --> 03:08.680 OK, so here we have, let's see, ADR method, which will have different implementations for specific 03:08.770 --> 03:09.710 rectangular cube. 03:09.960 --> 03:17.640 So for all of these, the method area will remain the same, but how it acts would change. 03:17.820 --> 03:22.740 So for Sfeir it will calculate the area differently for so-called beguilingly the. 03:23.340 --> 03:29.700 So that is what polymorphism is and it is one such methodology and Opsware one task and be performed 03:29.700 --> 03:31.810 in several different ways. 03:32.070 --> 03:35.460 So that is exactly what polymorphism is. 03:35.640 --> 03:42.660 Then we can use the same name for a method, but it will act differently based on what my object is, 03:42.930 --> 03:44.590 the nature of my object. 03:44.590 --> 03:47.340 So based on the nature of our flag differently. 03:48.210 --> 03:53.490 OK, so let's go ahead with the coding part of it. 03:57.660 --> 03:57.990 OK. 04:06.100 --> 04:11.230 So here I'm creating a class, this class is called your dog. 04:11.290 --> 04:14.580 And inside this, I will define the method. 04:14.920 --> 04:24.180 So first of all, I define in it and it will take in self, which is by default and it will take in 04:24.190 --> 04:26.530 the next. 04:26.950 --> 04:33.130 It will say self, not name is equal to a name. 04:33.920 --> 04:38.560 And let me define another method. 04:38.560 --> 04:44.140 Say this and I will speak so in speak. 04:44.140 --> 04:47.110 I will take says I don't need anything else. 04:47.320 --> 04:48.400 I'm inside this. 04:48.400 --> 04:55.720 I will say that Don and I will say self dog name plus 04:58.300 --> 05:07.720 says if I put this in quotes. 05:11.200 --> 05:13.770 So this is one of my string. 05:14.050 --> 05:18.130 Similarly, I create a similar class for CAT. 05:20.320 --> 05:28.590 So when I create this class for CAT and change its name for From Dog to God and everything else remains 05:28.600 --> 05:29.020 the same. 05:29.020 --> 05:32.020 But here the cat will instead see me. 05:35.850 --> 05:45.960 OK, now you can see here the speaker is present in case of class dog, and this method is saying, 05:45.960 --> 05:54.450 Wolf, as a result and in case of Gatica saying now and we have the same method, the name, OK, so 05:54.450 --> 05:56.510 we are using the same method names. 05:56.510 --> 06:06.150 So when I create, let's say, some examples, I'm creating a dog Dominico and I see a dog and I give 06:06.150 --> 06:08.790 it a name, Nikou. 06:09.960 --> 06:19.890 And similarly, I create a cat Feliks and I'll give it the name, the same as that. 06:21.640 --> 06:31.950 And after that, when we will simply print, we print Nicole don't speak. 06:32.670 --> 06:34.620 And similarly, we print. 06:37.060 --> 06:48.790 Felix, don't speak, and we will have to run this method, so we'll run this method and when we will 06:48.790 --> 06:50.650 run this, what will happen? 06:51.130 --> 06:59.220 So it gives me Niko says, well, Felix is like in outer space here so that it looks a little better. 07:00.550 --> 07:01.230 So you can see. 07:01.540 --> 07:07.570 So what we have achieved here is we have achieved the same method. 07:07.900 --> 07:15.640 We have implemented the same method of name, and we have achieved a different behavior out of those. 07:15.910 --> 07:19.060 So I can have any number of animals. 07:19.060 --> 07:27.520 I can have double got a cow and horses and pigs and whatever, and all of those can have their different 07:27.520 --> 07:28.030 sound. 07:28.030 --> 07:35.680 And for all I can use the same method and it will be so very convenient to use this. 07:35.890 --> 07:42.770 And I will not be confused by finding out while remembering what me might have used. 07:42.940 --> 07:46.450 So this is the convenience which will provide you. 07:47.470 --> 07:57.400 So here we have a dog class and a class and each has a dog speak method when called the object as we 07:57.750 --> 07:58.420 speak. 07:58.420 --> 08:06.730 So we are calling these objects as dog speak and they will retain redounded unique object. 08:06.740 --> 08:11.920 So the result will be unique based on what object they have. 08:12.470 --> 08:20.410 So similarly we can have different things so we can implement these differently. 08:20.410 --> 08:25.390 I'll send them out during the code so you will find those in code. 08:25.960 --> 08:38.890 Now, in case of classes, it is a more common practice where we can use abstract classes and inheritance. 08:39.190 --> 08:45.400 So we have seen inheritance or you're right, so here we have seen an inheritance. 08:45.410 --> 08:51.640 So here we have a class animal and we have created some particular method here. 08:51.640 --> 08:56.860 And this method is being overridden here in the US. 08:57.250 --> 09:05.170 But there could be a scenario where I want to create some method in case of the best in class and I 09:05.170 --> 09:09.720 want to implement those only in the class or something like that. 09:09.940 --> 09:18.520 So that is the place where we can use abstract class or an abstract class is one that never expected 09:18.520 --> 09:19.930 to be instantiated. 09:19.930 --> 09:23.980 So it will not expect any instantiation of. 09:23.980 --> 09:26.860 So we will never have an animal object. 09:27.100 --> 09:33.410 Only dog and cat object will be present, although dog and cat are derived from the animals. 09:33.610 --> 09:36.680 So we will be creating something like that. 09:36.760 --> 09:41.350 We will be creating dog and cat classes which will be derived from the animal flies. 09:41.620 --> 09:45.220 But in case of animal class, we won't instantiate that ever. 09:46.690 --> 09:50.080 So let's do that without losing any time. 09:50.350 --> 09:52.330 So I will say class 09:54.700 --> 09:58.840 animal and I see the. 10:12.830 --> 10:20.570 So what I have done here is I have created this class animal inside this class, I have given the definition 10:20.570 --> 10:24.980 for in it and I have given the attribute name inside this. 10:25.850 --> 10:33.980 After that, I have given the function, the method to speak and for this method speak. 10:33.980 --> 10:40.280 I am saying that the reason is not implemented error, saying that subclause must be implementing this 10:40.280 --> 10:41.060 abstract method. 10:41.480 --> 10:45.460 OK, so abstract method is defined by conventional. 10:45.670 --> 10:47.480 So this is defined like this only. 10:48.150 --> 10:50.480 OK, this will be defined like this. 10:50.900 --> 10:57.290 And after that I'm creating this class and this guy does just how we have implemented it. 10:57.290 --> 11:05.540 Olio in the same way we have simply said to the class dog and we have said def speak, self written, 11:05.540 --> 11:09.100 self taught name Seawolf said don't mean meal. 11:09.440 --> 11:17.360 And then I see pre the class create an object dog and create an object for God. 11:17.570 --> 11:21.560 And then I bring to the door and I start to speak. 11:22.730 --> 11:24.070 So let me run this. 11:24.350 --> 11:28.240 So it gives me Vidor's is Wolf ISIS ISIS's. 11:29.210 --> 11:33.440 So here what we have done is we have created this. 11:34.040 --> 11:41.590 Now let me do something like let me not define this here. 11:41.750 --> 11:45.600 So if I would not define these definitions. 11:45.600 --> 11:48.270 So let me not define it for just one class. 11:49.640 --> 11:55.700 So here it is seeing that it is expecting some intended block. 11:55.710 --> 12:02.600 So let me put parse here, first of all, so you can see it is giving out the not implemented error 12:02.600 --> 12:05.630 in same subclass must be implemented abstract method. 12:05.900 --> 12:08.390 So it is saying that it needs to implement this. 12:08.830 --> 12:11.670 OK, so that is what this means. 12:11.690 --> 12:12.860 Or an abstract class. 12:12.860 --> 12:23.540 We can create an abstract class by defining this is not implemented error and that we make it mandatory 12:23.840 --> 12:28.400 for us to implement it under the child classes. 12:29.960 --> 12:38.660 OK, so in real life, examples of what polymorphism we can have, something like when we are opening 12:38.660 --> 12:45.420 different file types so different tools are needed to display so would be difficult. 12:45.950 --> 12:46.480 Exactly. 12:46.520 --> 12:47.300 Exactly right. 12:47.780 --> 12:52.760 So in those case we can have a different kind of file. 12:52.760 --> 12:57.620 So different kind of handling for different files and they can have different methods for that. 12:57.840 --> 13:04.340 We can use the same method, open file, but each file will be opened differently based on the life 13:04.340 --> 13:04.910 from it. 13:04.910 --> 13:09.390 Just in another example would be when we are adding different object. 13:10.490 --> 13:18.530 So in that case, the class operator will perform an automatic operation by when we are adding the strings, 13:18.530 --> 13:21.460 it will this act as a concatenation. 13:21.770 --> 13:22.110 Right. 13:22.280 --> 13:27.950 So these are different examples that we have now. 13:27.950 --> 13:32.690 Apart from that, the next topic which we have is encapsulation. 13:32.690 --> 13:36.040 So we will be discussing that in the next session.