1 00:00:00,089 --> 00:00:06,060 Hi and welcome to this new section where you'll learn about object-oriented 2 00:00:06,060 --> 00:00:12,570 programming often referred to as OOP for short. Now if you have experience 3 00:00:12,570 --> 00:00:16,770 with programming that's probably a familiar concept for you because OOP 4 00:00:16,770 --> 00:00:22,260 is used in most of the languages, but I assume you don't know anything 5 00:00:22,260 --> 00:00:27,449 about object-oriented programming so I'll explain the concept from the 6 00:00:27,449 --> 00:00:33,719 beginning. Now there are various definitions of OOP out there and some 7 00:00:33,719 --> 00:00:39,600 get very tricky, but I believe the best one to know is that object-oriented 8 00:00:39,600 --> 00:00:47,160 programming is just a way to organize your code. That means Opie is not a must. 9 00:00:47,160 --> 00:00:52,620 So you can simply use functions to build an application as we did here with our 10 00:00:52,620 --> 00:00:57,140 bookstore application, and many programmers choose to not use 11 00:00:57,140 --> 00:01:03,870 object-oriented programming to organize their code, they don't use the OOP way 12 00:01:03,870 --> 00:01:10,590 to write their code in other words. However it is generally accepted that if 13 00:01:10,590 --> 00:01:17,640 you have more than two functions which apply operations to the same object, 14 00:01:17,640 --> 00:01:23,040 for instance a program that applies operations to a tkinter interface, so 15 00:01:23,040 --> 00:01:27,450 you have this callback functions, and so you should organize these functions into 16 00:01:27,450 --> 00:01:34,369 something called a class. Now because object-oriented programming is a complex 17 00:01:34,369 --> 00:01:41,159 concept I didn't include that in the beginning of this course, so I wanted 18 00:01:41,159 --> 00:01:46,549 that you first built some applications using functions which is more intuitive, 19 00:01:46,549 --> 00:01:53,189 and then you move to object-oriented programming. So back to our graphical 20 00:01:53,189 --> 00:01:58,619 user interface application. So the object here, I'm talking about objects and the object 21 00:01:58,619 --> 00:02:07,259 here is the entire window with buttons and other widgets as well now we can put 22 00:02:07,259 --> 00:02:12,330 all the attributes that define this object so this window such as 23 00:02:12,330 --> 00:02:16,319 the title of the buttons, the label, and also the callback functions 24 00:02:16,319 --> 00:02:22,530 attached to this object inside the class. So in our application we didn't use 25 00:02:22,530 --> 00:02:27,870 classes, we used functions so this script here does not apply to object-oriented 26 00:02:27,870 --> 00:02:32,970 programming, and putting this object inside a class means we are organizing 27 00:02:32,970 --> 00:02:37,410 the code in a class which creates, an object so that's why we call it 28 00:02:37,410 --> 00:02:42,180 object-oriented programming. And using classes to organize your code 29 00:02:42,180 --> 00:02:48,720 is referred to as object-oriented programming, and what I'll do next is in 30 00:02:48,720 --> 00:02:56,180 my backend script where I have the database operations I'll transform this script by 31 00:02:56,180 --> 00:03:02,700 putting this inside a class and after that you can do the same for the frontend 32 00:03:02,700 --> 00:03:06,930 interface so that you practice object-oriented programming. Now my 33 00:03:06,930 --> 00:03:11,819 purpose here is not to train you how to write classes. I first want you to 34 00:03:11,819 --> 00:03:15,870 understand classes, and many learning resources explain object-oriented 35 00:03:15,870 --> 00:03:21,480 programming by saying something like we create a class that creates a dog object, 36 00:03:21,480 --> 00:03:26,910 and the dogs can eat, and bark and so on. That's a good example to train 37 00:03:26,910 --> 00:03:31,829 you to learn the syntax of a class, but hey what is a dog in in programming? 38 00:03:31,829 --> 00:03:35,910 I mean you can scratch your head all day trying to come up with 39 00:03:35,910 --> 00:03:43,319 a scenario where you have a dog as an object in your application, and then that 40 00:03:43,319 --> 00:03:47,370 still a good example, but only if you have some years of experience in programming, 41 00:03:47,370 --> 00:03:54,959 and you can quickly think of where and when to use classes based on such 42 00:03:54,959 --> 00:03:59,340 examples. I assume you don't have these years of experience, so I'll use 43 00:03:59,340 --> 00:04:05,569 real programming objects in this section to explain such a tricky concept as 44 00:04:05,569 --> 00:04:11,160 object-oriented programming. So the best way to understand OOP is to first build 45 00:04:11,160 --> 00:04:17,070 a program with a known object oriented programming approach, so using functions, 46 00:04:17,070 --> 00:04:24,510 and once you know that program well, then you build that program again using 47 00:04:24,510 --> 00:04:30,570 OOP, and then you automatically understand what OOP is by looking at how 48 00:04:30,570 --> 00:04:37,410 things are different. So let me organize this code using classes now and later 49 00:04:37,410 --> 00:04:42,450 we will build a simpler program from scratch where we create a bank 50 00:04:42,450 --> 00:04:47,460 account object with Python, and we will apply functions to that object such as 51 00:04:47,460 --> 00:04:54,030 withdraw, deposit, and so on. That's great, and yeah, that's about this 52 00:04:54,030 --> 00:04:58,200 introduction, and let's move on to the next lecture and write some classes.