Description
Coding best practices is a phrase we hear often, but how often do we actually take time to stop and examine the patterns we use every day? In this short talk, I’ll share a few selected practices and anti-patterns that I came across over the last year. We’ll cover these practices through live coding examples and design tradeoffs, focusing on where things can go wrong, even when they seem right.
Bio
Nadav Mary is a Principal Software Engineer at Palo Alto Networks, where he's been working on diverse challenges across backend, frontend, and infrastructure for the past 10 years.
He's led development efforts across multiple teams, driving improvements in architecture, developer experience, and team collaboration. Nadav is passionate about clean code, mentoring engineers, and helping others grow into better versions of themselves. He cares deeply about doing things right and helping others level up.
Length
30 min
Transcript
1 00:00:01.980 --> 00:00:14.580 Gabor Szabo: So, hello, and welcome to this session. This… if you're watching on YouTube, then it's the Code Maven channel. My name is Gabor Szabo, I organize these events. This time, it's Nadav Marin, who is going to
2 00:00:14.800 --> 00:00:19.140 Gabor Szabo: talk about, some stuff in Python.
3 00:00:19.260 --> 00:00:25.419 Gabor Szabo: He will introduce himself, and they'll introduce his presentation.
4 00:00:25.530 --> 00:00:38.669 Gabor Szabo: If you are here at the event, thank you very much for joining us. Feel free to ask questions. That's the big privilege of being present at the event. And if you're watching on YouTube, then below the video you will find
5 00:00:38.670 --> 00:00:53.409 Gabor Szabo: the like button, and you can follow the channel, and you can also find a link to the future events, and also notes about this event, and links to things about Nadav, so that would be a good idea to follow them there.
6 00:00:53.500 --> 00:01:04.710 Gabor Szabo: With this, let me give the stage to you, Nadav. Thank you very much for agreeing to give this presentation, and really, the stage is yours.
7 00:01:05.830 --> 00:01:10.459 Nadav Mary: Thank you, so let me share my screen. Just let me know that you can see that.
8 00:01:10.460 --> 00:01:11.739 Gabor Szabo: Yes, we can see.
9 00:01:12.110 --> 00:01:12.940 Nadav Mary: Facts?
10 00:01:13.330 --> 00:01:21.380 Nadav Mary: All right, so, hi everyone, and thanks for joining my session. Let me start with a quick question.
11 00:01:22.310 --> 00:01:29.050 Nadav Mary: So actually, now that AI can write the code for us, do we really need to care about
12 00:01:29.280 --> 00:01:36.670 Nadav Mary: coding best practices, Keep the question in mind, and we'll go through that question in this session.
13 00:01:38.560 --> 00:01:52.090 Nadav Mary: Yeah, so for those who don't know me, I'm Nadav Mahri, I'm Principal Software Engineer at Palo Alto Networks. I've been with the company for the last 10 years, going back to my CyberAc days before the acquisition.
14 00:01:52.690 --> 00:02:09.999 Nadav Mary: I love solving design problems, but what I love even more is helping other developers grow. Watching someone from going from, I'll just make it work, to understand why this is the right solution, this is my, really, passion.
15 00:02:10.190 --> 00:02:18.049 Nadav Mary: I'm also known as the clean code guy, or as my teammates put it, the one who actually reads the pull request.
16 00:02:18.250 --> 00:02:29.500 Nadav Mary: And now, seriously, over the last 10 years, I've worked across different teams, different languages, backend and front-end, and reviewed a lot of code.
17 00:02:29.970 --> 00:02:40.949 Nadav Mary: And I've seen the same problem over and over again. Code that works, code that looks reasonable, but code that's built around a design that doesn't quite fit the problem.
18 00:02:41.950 --> 00:02:44.650 Nadav Mary: And you don't always notice it immediately.
19 00:02:44.770 --> 00:02:49.500 Nadav Mary: Usually, you will notice it months later, when simple change becomes
20 00:02:49.620 --> 00:02:59.750 Nadav Mary: Complicated, or when testing becomes painful, or when adding one feature means touching five different areas or classes in the code.
21 00:02:59.920 --> 00:03:18.720 Nadav Mary: And today, nowadays, AI is changing the way we develop software. It can write code incredibly fast, incredibly cheap, generate the entire implementation, suggest design patterns, and produce code that looks clean and well-structured.
22 00:03:18.920 --> 00:03:35.619 Nadav Mary: But here's something that I've been thinking a lot about since the AI came into our life. When AI generates a solution that looks perfectly reasonable, how do we know, actually, if this is the right solution?
23 00:03:36.820 --> 00:03:46.829 Nadav Mary: And this is something that I want us to explore together today. We're going soon to open the IDE and build something together, of course, in Python.
24 00:03:47.800 --> 00:03:59.570 Nadav Mary: And we'll start with a solution that seems perfectly reasonable, and then we'll introduce new requirements, discover some design problems, and see how we can improve the solution.
25 00:04:00.170 --> 00:04:12.389 Nadav Mary: We're going to revisit a few familiar coding practices, and I'm not here to teach you the definitions or anything like that. I guess that most of your… maybe all of you probably have heard about them before.
26 00:04:13.060 --> 00:04:18.100 Nadav Mary: My goal is to sharpen your instinct for when and why to apply them.
27 00:04:18.250 --> 00:04:32.540 Nadav Mary: And hopefully, you will live with a few simple rules of thumb that help you recognize these design problems earlier, whether if the code was written by you, or a teammate, or an AI agent.
28 00:04:32.670 --> 00:04:42.509 Nadav Mary: And I'm not going to reveal the design problems up front, that would be… that will spoil the fun, and we'll discover them together as we code.
29 00:04:42.880 --> 00:04:52.910 Nadav Mary: Yeah, so let's just jump into it and open the idea. I will use a cursor that also will be my assistant and will help me,
30 00:04:53.070 --> 00:04:54.600 Nadav Mary: code.
31 00:04:54.970 --> 00:04:57.760 Nadav Mary: And we're going today to build,
32 00:04:58.030 --> 00:05:16.659 Nadav Mary: a vehicle system, we're going to model a vehicle system, and we're going to start simple, having two different types of vehicles. We'll have the gasoline vehicle, which is run by gas, of course, and the electric vehicle, which is run by electricity, of course.
33 00:05:17.800 --> 00:05:25.090 Nadav Mary: And for our first implementation, I'm going to create a class of vehicles. It's going to be an abstract class.
34 00:05:25.310 --> 00:05:30.389 Nadav Mary: And, our base class will first have
35 00:05:30.550 --> 00:05:33.520 Nadav Mary: With Free Staff 2, and…
36 00:05:33.710 --> 00:05:42.960 Nadav Mary: main members. One would be the year of the vehicle, and the second will be, let's say, the model, and we'll save this,
37 00:05:43.140 --> 00:05:46.080 Nadav Mary: These members, on our class.
38 00:05:46.310 --> 00:05:53.480 Nadav Mary: And then we'll have an abstract method for starting, the, yeah, the, the vehicle.
39 00:05:53.990 --> 00:05:56.170 Nadav Mary: So we'll have the dev start.
40 00:05:56.450 --> 00:06:00.569 Nadav Mary: And this is an abstract method, so it will be implemented by the inheritors.
41 00:06:00.790 --> 00:06:11.159 Nadav Mary: And then we're going to have two different vehicles. As we've said, we'll have the gasoline and the electric vehicle, so let's implement them. So we'll have the gasoline vehicle.
42 00:06:11.310 --> 00:06:21.200 Nadav Mary: And, of course, we'll inherit from vehicle, and the gasoline vehicle will introduce, of course, the year and the model, and also will have the gas level.
43 00:06:21.850 --> 00:06:31.930 Nadav Mary: of the car, of the vehicle, and of course, we'll call Super.na, thanks, for Cursor, for holding the ear and the model, by the base class.
44 00:06:32.130 --> 00:06:38.679 Nadav Mary: And of course, we'll, hold the gas level also on, as a member in our,
45 00:06:38.790 --> 00:06:44.129 Nadav Mary: In the gasoline vehicle, And we'll, of course, have to implement our start method.
46 00:06:44.310 --> 00:06:45.040 Nadav Mary: Oh…
47 00:06:45.550 --> 00:06:59.820 Nadav Mary: Let's say that our implementation, yeah, just will be printing out that we're starting the car, the gasoline vehicle, let's also put over here, starting gasoline vehicle, printing the model and the gas level.
48 00:07:01.040 --> 00:07:04.609 Nadav Mary: And that's… Do just the same for the electric vehicle.
49 00:07:05.570 --> 00:07:15.820 Nadav Mary: And just the same will inherit from the vehicle, and our constructor, this time will get the air and the model just the same, and this time we'll get the battery level.
50 00:07:15.950 --> 00:07:32.129 Nadav Mary: And we'll hold the battery level as the data member in the electric vehicle, and our start method will do pretty much as similar as the gasoline vehicle, and we'll print out the model and the battery level of the electric vehicle.
51 00:07:32.920 --> 00:07:41.600 Nadav Mary: Perfect. And now we can go ahead and create an electric vehicle, and call to start, and when we run that.
52 00:07:41.960 --> 00:07:49.360 Nadav Mary: So we can see down here that we're starting the electric vehicle, and everything works as we, expect.
53 00:07:49.780 --> 00:07:54.100 Nadav Mary: Let's say that we are running the system for a while, for months, for…
54 00:07:54.330 --> 00:07:57.599 Nadav Mary: Whatever time it is. And then,
55 00:07:57.820 --> 00:08:08.470 Nadav Mary: We're getting a new requirement, and we want to support a hybrid vehicle. A hybrid vehicle, of course, that is running both on gas and on electricity.
56 00:08:09.250 --> 00:08:21.009 Nadav Mary: And of course, as good developers who want to perform code reuse, we want to reuse the capabilities that we already implemented in our gasoline and the electric vehicle.
57 00:08:22.060 --> 00:08:32.870 Nadav Mary: And for our implementation, we'd like to create a class, and this will be our first suggestion for creating the Harvard vehicle.
58 00:08:32.870 --> 00:08:44.000 Nadav Mary: And we'll use multiple inheritance, and we'll inherit both from gasoline and the electric vehicle, because we want to reuse the capabilities that these two classes are giving us.
59 00:08:44.330 --> 00:08:55.260 Nadav Mary: And Python also allows us to use multiple inheritance, so there is nothing wrong about about that.
60 00:08:55.730 --> 00:09:03.220 Nadav Mary: And then, for our constructor, of course, we'll hold the air, the model, and both gas and the battery level.
61 00:09:03.320 --> 00:09:10.800 Nadav Mary: And let's start by calling super.init with all the parameters, the year, the model, gas level, and battery level.
62 00:09:10.900 --> 00:09:20.580 Nadav Mary: And also, let's implement our start method. Yeah, start with the hybrid vehicle, and we'll print out the model, the gas level, and the battery.
63 00:09:21.730 --> 00:09:40.680 Nadav Mary: let's go ahead and try to initialize and calling the electric… no, the electric vehicle, sorry, the hybrid vehicle, let's do it again. So, let's initialize the hybrid vehicle, and calling the start method, and then we'll try and drown that for encountering our first issue.
64 00:09:41.780 --> 00:09:56.099 Nadav Mary: And if we're looking closely, so basically we've called in our constructor super.inate, and we can see over here that actually this super.init, as expected, by the way, is calling to gasolinevehicle.init.
65 00:09:56.700 --> 00:10:06.570 Nadav Mary: And this is since our hybrid vehicle is inheriting from gasoline vehicle first, and this is the reason that gasoline vehicle's constructor is being called.
66 00:10:07.510 --> 00:10:21.500 Nadav Mary: And we can see here that it gets less parameters than we're passing over here. We're passing also the battery level, which is not expect… is not accepted by the gasoline vehicles constructor, and this is the reason
67 00:10:21.500 --> 00:10:29.229 Nadav Mary: we're getting that error. And, one solution for that, there are various solutions for this.
68 00:10:30.750 --> 00:10:48.850 Nadav Mary: And we'll go for one solution. This is calling… instead of calling super.init, and we'll talk deeply about that just in a few moments, we'll call explicitly to gasolinevehicle.init as a static call, and this time we'll have to pass self.
69 00:10:48.960 --> 00:10:58.390 Nadav Mary: And of course, we'll call also electric vehicle.init, and we'll call it the gasoline vehicle only with the gas level, so we'll delete the battery level.
70 00:10:59.670 --> 00:11:01.120 Nadav Mary: And pretty much…
71 00:11:02.270 --> 00:11:07.519 Nadav Mary: Let's hope that this is it, and now it will work, so let's go and run the code.
72 00:11:08.010 --> 00:11:13.059 Nadav Mary: And no, it seems that they were still having an issue, and they will dig into it.
73 00:11:13.200 --> 00:11:21.879 Nadav Mary: So we can see that our init function… go and see the status, right? So, our init function calls the gasolinevehicle.init.
74 00:11:22.310 --> 00:11:26.620 Nadav Mary: And then we're having… we're hitting the super.init.
75 00:11:26.720 --> 00:11:33.180 Nadav Mary: And this time we got the electric vehicle that is missing one requirement parameter of the battery level.
76 00:11:33.460 --> 00:11:48.260 Nadav Mary: And then, here, we can say that things are becoming more complicated, because this is something we wouldn't expect when calling super, that suddenly electric vehicles constructor will be called.
77 00:11:48.320 --> 00:12:03.009 Nadav Mary: And the reason for that is a mechanism in, that is, is being applied in Python and in many other languages that is called the Method Resolution Order, MLO.
78 00:12:03.060 --> 00:12:13.499 Nadav Mary: And the MRO is becoming confusing, and something you should be familiar with when dealing, especially with multiple inheritance.
79 00:12:13.620 --> 00:12:22.889 Nadav Mary: Because you might think that calling super.something will… will call your parents, function, but this is not the case.
80 00:12:22.950 --> 00:12:30.340 Nadav Mary: Not necessarily the case when dealing with multiple inheritance. When calling super, what is actually happening is that
81 00:12:30.400 --> 00:12:47.790 Nadav Mary: in Python, in the other languages, Python is building how the method resolution will be ordered. And when dealing with multiple inheritance, the method resolution order will be when we're having the hybrid vehicle, then
82 00:12:47.790 --> 00:12:58.210 Nadav Mary: The first inherited gasoline vehicle, and then the next method resolution order will be taken from the electric vehicle, and then from the base class of the vehicle.
83 00:12:58.330 --> 00:13:01.690 Nadav Mary: So when we hit, GaslonVehicle.innit.
84 00:13:02.000 --> 00:13:07.760 Nadav Mary: And then, when we called super.net from the gasoline vehicle, we actually called for the next
85 00:13:07.830 --> 00:13:24.929 Nadav Mary: method in the… in the order, and super does need in this time, so we started from hybrid vehicle, then we arrived to gasoline vehicle, and the next method will be from the electric vehicle, and not from the vehicle. And this is the confusion, and this is the confusing point.
86 00:13:25.400 --> 00:13:33.589 Nadav Mary: About, calling, super. And this is the reason where we, we reached out from the gasoline vehicle into the electric vehicle.
87 00:13:34.900 --> 00:13:45.300 Nadav Mary: And since we are calling super.init with an ear and a model, and in our case, calling super is actually calling to electric vehicles constructor.
88 00:13:45.640 --> 00:13:59.919 Nadav Mary: This is why we're missing some parameters, as we've said… as being said here in the… in the yellow, that we're missing one required position algorithm, which… which is the battery level, since super.Nate of the gasoline vehicle passes only the air in the model.
89 00:14:00.820 --> 00:14:01.550 Nadav Mary: bomb.
90 00:14:01.590 --> 00:14:12.289 Nadav Mary: And this is… and we can solve this issue just as we've solved the previous problem, so we can explicitly, instead of calling super.
91 00:14:12.290 --> 00:14:25.840 Nadav Mary: We actually wanted the vehicle being called, so we can just explicitly call vehicle.init, and we'll pass here self, both in the gasoline, in the electric vehicle, you know, constructor.
92 00:14:26.030 --> 00:14:41.419 Nadav Mary: And then our problem will be solved. Let's run the code right now and see if everything is fine, and we can see here that we're starting our Harvard vehicle with the gas level and the battery level.
93 00:14:41.600 --> 00:14:59.030 Nadav Mary: And everything is fine, but as we said at the beginning, we want our… we want to make as much reuse of our code as possible, and we can see that our start method doesn't…
94 00:14:59.040 --> 00:15:07.659 Nadav Mary: doesn't reuse the start from the electric and the gasoline vehicle. So let's play a little bit with that and see.
95 00:15:07.660 --> 00:15:12.350 Gabor Szabo: Nadav, sorry, could you change the number so they won't be both 100?
96 00:15:12.840 --> 00:15:13.729 Nadav Mary: Yeah, of course.
97 00:15:14.130 --> 00:15:14.970 Nadav Mary: Of course.
98 00:15:16.110 --> 00:15:27.909 Nadav Mary: So let's say that our… yeah, our battery level is on 50 and 100 for the gas level. Let's run it again, so now we can see the difference. Perfect.
99 00:15:28.230 --> 00:15:32.000 Gabor Szabo: Just to make sure that the numbers are in the correct place, and not… Yeah.
100 00:15:32.180 --> 00:15:34.440 Nadav Mary: Absolutely right. Yeah, yeah.
101 00:15:34.580 --> 00:15:37.810 Nadav Mary: Perfect. So,
102 00:15:37.920 --> 00:15:54.060 Nadav Mary: Yeah, so let's try and perform code reviews in our start method, and we already talked about the MRO and its confusion about how it behaves, so let's first go and call super.start and see,
103 00:15:54.300 --> 00:15:57.270 Nadav Mary: How it goes and what we're getting.
104 00:15:57.990 --> 00:16:02.390 Nadav Mary: So now we can see that we're calling to starting gasoline vehicle.
105 00:16:02.520 --> 00:16:10.249 Nadav Mary: And then we're calling to our starting hybrid vehicle, but we do not call our electric vehicle at all.
106 00:16:10.510 --> 00:16:15.890 Nadav Mary: And as we said, we want to use both of our capabilities from both electric and the gasoline vehicle.
107 00:16:17.390 --> 00:16:34.520 Nadav Mary: And let's take it even farther. We already talked about the MRO, the method, resolution, and order. If we'll go here and replace the way that we are inheriting, so we'll inherit from the electric vehicle and then from the gasoline vehicle, then we'll run our program.
108 00:16:34.740 --> 00:16:45.420 Nadav Mary: So, surprisingly, or maybe now, and not that surprisingly, now that we understand the MRO, we're seeing that we arrived to our electric vehicle start function.
109 00:16:45.560 --> 00:16:54.399 Nadav Mary: And then to the hybrid vehicle. But we didn't get into our gasoline vehicle. So, as we can see here, the,
110 00:16:55.030 --> 00:17:13.379 Nadav Mary: the order that we are inheriting from our electric and the gasoline vehicle actually influences our behavior of the code, and this is something that I think that we wouldn't expect, but in our case, it did influence it.
111 00:17:15.220 --> 00:17:30.399 Nadav Mary: Perfect. So in order to fix that, so we already learned about calling explicitly to gasolineVehicle.it its function, so we could call gasolineVehicle.start, and electric vehicle.start in our start method, and it would solve the problem.
112 00:17:31.420 --> 00:17:41.709 Nadav Mary: But let's learn another technique that we can do over here, and this is calling the super.start, and taking advantage of the MRO,
113 00:17:41.910 --> 00:17:50.229 Nadav Mary: In both of our gasoline and the electric vehicle, and as we've said, since we're calling Super.start, so our first
114 00:17:50.280 --> 00:18:10.279 Nadav Mary: method resolution order will go this time to the electric vehicle start function, and then the super.start over here will go to the next method in the order, and it will go to the gasoline vehicles start method, and then it will print out the gasoline vehicle, then the electric vehicle start, and then we'll see the hybrid vehicle
115 00:18:10.690 --> 00:18:13.139 Nadav Mary: So let's run and say that this is the…
116 00:18:13.290 --> 00:18:29.809 Nadav Mary: the way it behaves, and as we've said, this is our expected behavior, and again, as we've seen before, if I flip again the inheritance order, so our behavior will be changed.
117 00:18:29.900 --> 00:18:42.640 Nadav Mary: Okay, so in the first run, it was the gasoline vehicle that was hit first, then the electric vehicle, and now it was flipped since we have flipped our inheritance order.
118 00:18:42.750 --> 00:18:53.760 Nadav Mary: Alright, so it was pretty, pretty tough, stuff that we've been dealing here, and,
119 00:18:54.100 --> 00:19:10.329 Nadav Mary: you know, when I'm seeing this solution, it feels quite complicated to me, and we've been struggling with having here only four classes in our modeling system, and we already encountered so many issues.
120 00:19:10.420 --> 00:19:14.070 Nadav Mary: So this is a red flag, for me.
121 00:19:14.070 --> 00:19:31.849 Nadav Mary: And also, if I'm taking it a step further, since our… let's take the electric vehicle and our hybrid vehicle, so since the hybrid vehicle is inheriting from electric vehicle, so each new function or capability that will be applied to the electric vehicle
122 00:19:31.880 --> 00:19:50.510 Nadav Mary: will be automatically applied to our hybrid vehicle. So, for example, if we'll have a new… have a new capability of wireless charge for our, for our electric vehicle, and, of course, wireless charge will have to charge our battery level.
123 00:19:50.570 --> 00:20:07.910 Nadav Mary: So this capability will be automatically applied to our hybrid vehicle, and if I'll try to call over here, and the idea already completes what I want to do, and if I'll call in the hybrid vehicle the wireless charge, so
124 00:20:08.100 --> 00:20:21.960 Nadav Mary: And I'll run the program, so you can see that I got this capability automatically into my hybrid vehicle, although it was implemented in my base class of the electric vehicle, but
125 00:20:22.140 --> 00:20:35.820 Nadav Mary: maybe we do not want date capability. Maybe our hybrid vehicle doesn't support, or doesn't support yet, the wireless charge capability. So what we'll do then? Because now we can call this, and it's…
126 00:20:36.110 --> 00:20:49.270 Nadav Mary: you know, kind… kind of will be working, but it's not really what we were intended to do. So, I guess that what we'll do next will be go and…
127 00:20:50.460 --> 00:21:00.510 Nadav Mary: And then override the wireless charge function, and then we'll raise, yeah, a not implemented error, so if developers will go and call wireless charge, so they will encounter
128 00:21:00.660 --> 00:21:04.630 Nadav Mary: That exception, and then they'll know that they shouldn't do that.
129 00:21:05.120 --> 00:21:12.190 Nadav Mary: Yeah, so things becoming really, really smelly in our implementation.
130 00:21:12.340 --> 00:21:15.880 Nadav Mary: Let's stop here for a second and go back to our presentation.
131 00:21:17.480 --> 00:21:28.800 Nadav Mary: Perfect. So, let's talk, and let's talk a little bit more about the download inheritance problem that we just encountered, and in general, about inheritance.
132 00:21:30.070 --> 00:21:40.539 Nadav Mary: So, as we've seen, we've had a vehicle system, we started with a vehicle-based class, then we had the electric and the gasoline vehicle that we're inheriting from the vehicle.
133 00:21:40.560 --> 00:21:54.900 Nadav Mary: And then we added the hybrid vehicle, and we used multiple inheritance in order to achieve our capabilities, and then we encountered the download inheritance. Damode inheritance, basically, you can see it over here in this,
134 00:21:55.080 --> 00:22:01.749 Nadav Mary: In this diagram is when we have one class, the hybrid… in our case, it was the hybrid vehicle, which
135 00:22:02.380 --> 00:22:11.650 Nadav Mary: It inherits both with the… from two classes. In this example, it was the electric vehicle and the gasoline vehicle, and these two classes are inheriting from,
136 00:22:11.940 --> 00:22:28.779 Nadav Mary: the same ancestor. In our case, it's the vehicle, and then we get this shape of a diamond, and this is called the diamond inheritance problem, and we've seen various problems that we had to deal with, whether it's the method resolution.
137 00:22:29.480 --> 00:22:46.859 Nadav Mary: the confusing method resolution order, and also, we can say that we only have here four classes, and we only have a hierarchy tree level of level 2. We have the vehicle, electric gas vehicle, and under them, with the hybrid vehicle, it's a lot of
138 00:22:46.900 --> 00:22:52.749 Nadav Mary: Things that we need to follow in order to understand how, our system,
139 00:22:52.820 --> 00:23:10.819 Nadav Mary: is working, and also what will happen when we'll add more and more vehicle types? What will happen if we'll need to put a new vehicle between, I don't know, our electric vehicle and the hybrid vehicles? We'll need to refactor and change our whole modeling system.
140 00:23:11.100 --> 00:23:21.669 Nadav Mary: Great. So… Let's just take it and see what we can do in order to simplify our implementation.
141 00:23:22.740 --> 00:23:25.810 Nadav Mary: So I'm going back to the… to the IDE.
142 00:23:26.190 --> 00:23:29.959 Nadav Mary: And what we're going to do now is,
143 00:23:30.240 --> 00:23:33.700 Nadav Mary: He's doing a few things in order to flatten down
144 00:23:33.750 --> 00:23:49.480 Nadav Mary: flatten, actually, this inheritance chain. And, first of all, we'll go to the basics, and let's talk about our gasoline and our electric vehicle. So basically, the gasoline and the electric vehicle, they both hold
145 00:23:49.490 --> 00:24:03.410 Nadav Mary: the way that the vehicle is starting, whether by gas or whether by battery. So we're talking about the engine system. So what we're going to do now is instead of holding these capabilities of gas.
146 00:24:03.480 --> 00:24:06.069 Nadav Mary: And watery, and…
147 00:24:06.220 --> 00:24:23.729 Nadav Mary: directly in our vehicles, we're going to take it out into a new modeling hierarchy of engines. So, what I'm going to do is implement the engine class, it's going to be abstract.
148 00:24:24.270 --> 00:24:37.699 Nadav Mary: And we'll have an upset method for the start, to start the engine. Yeah, and then I'm going to have two new engines. I'm going to have the gasoline engine and the electric engine.
149 00:24:37.850 --> 00:24:41.570 Nadav Mary: Okay, so let's start with the gasoline engine, and…
150 00:24:41.880 --> 00:24:47.089 Nadav Mary: And its constructor will hold the gas level.
151 00:24:47.360 --> 00:24:52.769 Nadav Mary: As we've done before, and we're going to replace it, as we've done before in the gasoline vehicle.
152 00:24:52.910 --> 00:24:55.059 Nadav Mary: And we're going to hold the gas level.
153 00:24:55.570 --> 00:25:03.010 Nadav Mary: Inside the gasoline engine, and of course, we'll have to implement the start method, because we're inheriting from the engine.
154 00:25:03.340 --> 00:25:16.610 Nadav Mary: So our start method will simply, yeah, we'll start gasoline engine, and we'll print out the gas level, and we'll do just the same for the electric engine. Thank you, cursor.
155 00:25:16.690 --> 00:25:30.469 Nadav Mary: So we have the electric engine, we have the constructor, and we are holding the battery level in our electric engine, and our start function is starting the electric engine, and we're printing out the battery level.
156 00:25:30.620 --> 00:25:42.020 Nadav Mary: And now we're going to change our gasoline and the electric vehicles. We're not going to hold anymore the gas level itself, but instead we're going to hold and create the engine.
157 00:25:42.110 --> 00:25:56.439 Nadav Mary: of the gas level. So, we're composing, or is in composition of the gas level inside the gas… the gasoline vehicle. So, we're using composition and holding the gasoline engine.
158 00:25:56.480 --> 00:26:15.399 Nadav Mary: And now we'll have also to change our start implementation, and we'll call self.engine.gasLevel, and of course, our start function doesn't have to… maybe, no, let's leave it for now, but we'll call this time to the engine.start.
159 00:26:15.670 --> 00:26:21.200 Nadav Mary: Which will go ahead… will go to the gasoline engine start function.
160 00:26:21.340 --> 00:26:27.159 Nadav Mary: Perfect. And then we'll do the same for the electric vehicle. Instead of holding the battery level over here.
161 00:26:27.290 --> 00:26:38.660 Nadav Mary: We'll hold the electric engine instead, and we'll pass the battery level, and we'll fix our start function, also to call self.engine.start.
162 00:26:38.790 --> 00:26:44.870 Nadav Mary: And, of course, over here, the start function will take the battery level from the engine.
163 00:26:45.000 --> 00:26:53.559 Nadav Mary: And for our wireless charge, so just the same, we'll call self.engine.batteryLevel, and we'll increase it by 10, and…
164 00:26:54.040 --> 00:26:57.970 Nadav Mary: Of course, same for the printing out the battery level.
165 00:26:58.980 --> 00:27:03.490 Nadav Mary: Perfect. Now, we… we've prepared,
166 00:27:03.810 --> 00:27:08.239 Nadav Mary: the field for fixing our hybrid vehicle.
167 00:27:08.350 --> 00:27:16.380 Nadav Mary: So if you are thinking about that, and when thinking about inheritance, you should always keep in mind that,
168 00:27:17.580 --> 00:27:36.889 Nadav Mary: that inheritance is a relationship between two or more classes, and usually if you want to ensure that inheritance fits to your use case, just try and say whether your subclass is a type of the class. So, for example.
169 00:27:36.890 --> 00:27:47.789 Nadav Mary: let's try and put it on our use case. So, hybrid vehicle is a gasoline vehicle and electric vehicle, and in saying that, it doesn't really feel correct, because
170 00:27:47.790 --> 00:27:58.490 Nadav Mary: hybrid vehicle is not a gasoline vehicle, and neither an electric vehicle. They do share some common behaviors, common capabilities, but they don't
171 00:27:58.800 --> 00:28:06.910 Nadav Mary: They're not really the same. They don't share the same… they're not the same identity.
172 00:28:07.010 --> 00:28:23.189 Nadav Mary: But if we're talking about hybrid vehicle and the vehicle, the base class, or base class from the beginning, so we can say that the hybrid vehicle is a vehicle, and it will be absolutely valid. So, let's go ahead and inherit
173 00:28:23.190 --> 00:28:31.399 Nadav Mary: Directly from a vehicle, instead of, inheriting from both electric and And the gasoline vehicle.
174 00:28:31.470 --> 00:28:46.110 Nadav Mary: And now we can do just the same as we've done in our electric and gasoline vehicle, and instead of calling the init functions, we can just go and initialize our gasoline engine, and the electric engine, and
175 00:28:46.110 --> 00:28:54.140 Nadav Mary: Use, as well in our habit vehicle, using composition and holding these engines.
176 00:28:54.190 --> 00:29:01.990 Nadav Mary: in the hybrid vehicle. Then our start function, we don't need to call that anymore, super.start, because
177 00:29:02.150 --> 00:29:14.520 Nadav Mary: Our super.start will go to the vehicle, which is an absolute class that does nothing, so we can simply call self.gasolineEngine.start and self.electricEngine.start.
178 00:29:14.650 --> 00:29:24.759 Nadav Mary: And also, yeah, we can change over here our print in order to print the right… from the right place, the gas level and the battery level.
179 00:29:24.890 --> 00:29:35.529 Nadav Mary: And we don't need anymore this wireless charge, not implemented error, because we do not inherit anymore this function.
180 00:29:35.760 --> 00:29:42.050 Nadav Mary: The wireless charging, because we don't inherit from electric vehicle anymore, so we can just… Delete.
181 00:29:42.240 --> 00:29:50.210 Nadav Mary: And then we can delete the habitvehicle.wirelessChart, because it's not something that exists.
182 00:29:50.360 --> 00:29:53.419 Nadav Mary: On our hybrid vehicle. And…
183 00:29:53.620 --> 00:30:00.150 Nadav Mary: let's just hope that I did everything fine. I'll try to run the program.
184 00:30:00.420 --> 00:30:03.039 Nadav Mary: And it seems like I missed something.
185 00:30:06.920 --> 00:30:08.709 Nadav Mary: Let's see what I've missed…
186 00:30:12.700 --> 00:30:14.170 Nadav Mary: Seems like there is…
187 00:30:17.860 --> 00:30:19.679 Nadav Mary: Yeah, just a second…
188 00:30:33.830 --> 00:30:37.450 Nadav Mary: Inload syntax… deprecated.
189 00:30:38.010 --> 00:30:46.240 Nadav Mary: I think that they just… Have a typo somewhere…
190 00:30:59.330 --> 00:31:03.289 Nadav Mary: If any of you is seeing the typo, just let me know.
191 00:31:12.110 --> 00:31:13.539 Gabor Szabo: Can you show the whole arrow?
192 00:31:15.060 --> 00:31:15.420 Nadav Mary: Sorry.
193 00:31:15.420 --> 00:31:18.120 Gabor Szabo: Can you enlarge the… yeah, that one.
194 00:31:18.640 --> 00:31:23.600 Nadav Mary: Yeah, it seems like… Something's…
195 00:31:25.180 --> 00:31:27.230 Gabor Szabo: Close the editor and open it again.
196 00:31:27.230 --> 00:31:28.660 Nadav Mary: Yeah, let's try that.
197 00:31:30.780 --> 00:31:33.139 Nadav Mary: Let's killer terminal and see…
198 00:31:37.360 --> 00:31:38.740 Nadav Mary: Alright, thank you.
199 00:31:39.920 --> 00:31:43.420 Nadav Mary: Let's see, so our… Yeah.
200 00:31:43.660 --> 00:31:45.660 Nadav Mary: Hybrid vehicle.
201 00:31:46.010 --> 00:31:47.659 Nadav Mary: Don't have them there anymore.
202 00:31:48.060 --> 00:31:49.230 Nadav Mary: Just a second…
203 00:32:03.980 --> 00:32:04.950 Nadav Mary: Hmm.
204 00:32:13.540 --> 00:32:17.520 Gabor Szabo: If you don't initialize the period, then the model won't be assigned.
205 00:32:17.520 --> 00:32:21.329 Nadav Mary: All right, yeah, so I'm missing over here the super domain.
206 00:32:21.550 --> 00:32:33.229 Nadav Mary: And that's it. This was the missing part. We had to call to Super.ignate in order to initialize the year and the model, sorry for that. And now everything works, as we expect.
207 00:32:33.970 --> 00:32:46.160 Nadav Mary: Perfect. Also, yeah, what, assets we can do is… we don't need anymore to call super.star, the electric vehicle in the gasoline vehicle.
208 00:32:46.510 --> 00:33:03.030 Nadav Mary: Because, again, calling super.start just will point to the vehicle, which points to pretty much nothing, because this is an abstract method, we did it only to fix the method resolution order, and do the same here in the gasoline vehicle.
209 00:33:03.410 --> 00:33:09.870 Nadav Mary: And also, we don't need to call explicitly in the electric and the gasoline vehicle.
210 00:33:09.980 --> 00:33:19.089 Nadav Mary: to vehicle local, we can go back and call super.inet, and we'll do the same over here in the electric vehicle.
211 00:33:20.220 --> 00:33:27.570 Nadav Mary: And let's see that everything still works, and yeah, it seems that everything is working, and… And…
212 00:33:27.760 --> 00:33:45.539 Nadav Mary: I feel right now that the implementation, feels, way more predictable and more expected, in… compared to what we did before. Perfect. So let's go back to the presentation.
213 00:33:47.150 --> 00:34:01.450 Nadav Mary: Yeah, so basically what we've done here is using composition for the rest of the inheritance and the damage inheritance issues. So we have created new models for the engine and the electric and the gasoline engine.
214 00:34:01.890 --> 00:34:14.809 Nadav Mary: And then our… for our vehicle modeling, we've used composition also, so our electric vehicle and the gasoline vehicle now use composition in order to hold the electric and the gasoline engines.
215 00:34:15.070 --> 00:34:32.820 Nadav Mary: And our hybrid vehicle, we have flattened our hierarchy tree level, and instead of inheriting gasoline and the electric vehicle, as we've done before, is now inheriting directly from the base vehicle class, and is holding the gasoline and the electric engine.
216 00:34:33.110 --> 00:34:43.400 Nadav Mary: engines. Perfect. So we've talked, pretty much, a lot about inheritance and composition. Let's, I have a question.
217 00:34:43.889 --> 00:34:44.316 Gabor Szabo: But the.
218 00:34:44.530 --> 00:34:45.080 Nadav Mary: Yep.
219 00:34:45.550 --> 00:34:52.050 Gabor Szabo: Have you encountered any case where a diamond inheritance didn't make a problem?
220 00:34:53.749 --> 00:35:12.559 Nadav Mary: Basically, so, this example is taken from a real-world example that I've encountered in my job. Diamond inheritance usually will cause you problems, as we've seen over here.
221 00:35:12.659 --> 00:35:23.199 Nadav Mary: This… there is no… basically, there is not any problem using multiple inheritance, although you should be cautious also about multiple inheritance.
222 00:35:23.309 --> 00:35:40.719 Nadav Mary: But if we're talking about diamond inheritance, so in the end, you'll probably end up dealing with the MRO, the confusing MR role, and also think about it, that in our friendship implementation, we had to call the vehicle.net twice.
223 00:35:40.829 --> 00:35:58.559 Nadav Mary: both from the electric vehicle and the gasoline vehicle, when we initialized the hybrid vehicle. In our case, it didn't cause any problem, because the calling vehicles in it function was pretty much consistent, and it only initialized its members, but
224 00:35:58.609 --> 00:36:13.529 Nadav Mary: But in other cases, you might encounter issues. So, whenever you're dealing with download inheritance, I guess that it's a red flag for your implementation, and you might rethink about your code design.
225 00:36:14.620 --> 00:36:26.550 Gabor Szabo: I think, actually, if it was a real car, then this would… calling the initialization of the vehicle twice would mean… would be like turning the key twice.
226 00:36:27.050 --> 00:36:28.750 Nadav Mary: Yep. Yeah, yeah, that's correct.
227 00:36:28.960 --> 00:36:33.400 Gabor Szabo: These days, no one turns a key, but just pushes the button, but…
228 00:36:33.400 --> 00:36:41.820 Nadav Mary: Yeah, but then you will push the button twice, so it's the same… might be the same problem. Again, maybe pushing the button twice will cause nothing, but a good shot.
229 00:36:42.540 --> 00:36:43.160 Nadav Mary: Lucas.
230 00:36:43.360 --> 00:36:45.200 Nadav Mary: Or maybe turn the car off, absolutely.
231 00:36:45.870 --> 00:36:46.359 Gabor Szabo: Yeah, yeah.
232 00:36:46.360 --> 00:36:57.060 Nadav Mary: Because really, it depends on the implementation, and again, this is something that you wouldn't expect from your code, and this is when things can become worse.
233 00:36:59.380 --> 00:37:00.070 Gabor Szabo: Okay.
234 00:37:01.060 --> 00:37:11.609 Nadav Mary: Perfect. Yeah, so let's talk about, inheritance versus composition. Let's talk about pros and cons, in different aspects. So, when
235 00:37:11.610 --> 00:37:20.160 Nadav Mary: We're talking about the relationship type, so we already touched it, before. So, when talking about inheritance, we're talking about an is,
236 00:37:20.160 --> 00:37:31.989 Nadav Mary: relationship. So, a gasoline vehicle is a vehicle, and our hybrid vehicle, we thought that inheritance would fit, but hybrid vehicle isn't gasoline and electric vehicle.
237 00:37:32.090 --> 00:37:50.450 Nadav Mary: This is why, this is why we had the confusion, and of course, there are various of examples. I don't know, a rectangle is a shape, right? And this may be something that you are, you already heard so many times from your studies.
238 00:37:51.570 --> 00:38:03.550 Nadav Mary: And regarding composition, we're talking about a hash relationship. So, as we've seen, a car has an engine, and this is how you can know that composition will fit into your use case.
239 00:38:03.710 --> 00:38:06.500 Nadav Mary: Regarding, flexibility.
240 00:38:06.750 --> 00:38:17.430 Nadav Mary: So we've seen that inheritance introduced us a strict structure and deep hierarchies, so we're not very flexible when dealing with inheritance.
241 00:38:18.400 --> 00:38:33.129 Nadav Mary: If we want to add more classes to our inheritance chain, it might become difficult, or if we're adding more capabilities, so we're getting that immediately into our subclasses.
242 00:38:34.220 --> 00:38:44.719 Nadav Mary: And we're talking about composition, so we have more modularity, and it's easier to change. We have some modules, and we can plug and play the different classes into
243 00:38:44.720 --> 00:38:56.869 Nadav Mary: Into other classes, as we've seen with the gasoline vehicle, and we used composition to add the gasoline engine, then we had the hybrid vehicle, which also composed the gasoline engine.
244 00:38:56.870 --> 00:39:04.769 Nadav Mary: Or, for example, if we'll have the air conditioning system, so we can have more composition to our vehicles.
245 00:39:05.180 --> 00:39:06.489 Nadav Mary: And so on.
246 00:39:06.670 --> 00:39:20.410 Nadav Mary: Regarding code reusability, so inheritance, as we've seen, it highly encourages code reuse, but it can lead into tight coupling, as we've seen with wireless charging.
247 00:39:20.410 --> 00:39:30.560 Nadav Mary: function that we had to inherit, and there is an exception for our private vehicle when we didn't necessarily wanted this mobility.
248 00:39:31.000 --> 00:39:44.620 Nadav Mary: And regarding composition, it also encourages code reuse, and in this time, we're getting decoupled behavior also. And just a small notice.
249 00:39:44.720 --> 00:39:53.019 Nadav Mary: code… so when we're talking about code reviews, it's not necessarily talking about writing less code. In our new implementation, we have
250 00:39:53.060 --> 00:40:12.849 Nadav Mary: from what I remember, around 20 lines more code than our first implementation, but we're still having code reviews. We're still reusing the start from our volume and the electric engines, so we do have code reviews. We might write a little bit more code.
251 00:40:13.000 --> 00:40:15.969 Nadav Mary: But we are gaining more flexibility
252 00:40:16.290 --> 00:40:19.869 Nadav Mary: and, and the couple, behavior.
253 00:40:20.120 --> 00:40:22.560 Nadav Mary: And… talking about composition.
254 00:40:22.590 --> 00:40:40.449 Nadav Mary: Regarding the MRO, the method resolution order, so when dealing with a diamond inheritance, where we have to deal with confusing MRO, and we had to debug and understand how it works in order to understand what happened.
255 00:40:40.510 --> 00:40:43.940 Nadav Mary: And when talking about composition, it's not,
256 00:40:44.030 --> 00:40:45.980 Nadav Mary: It's not something that we had to deal with.
257 00:40:46.090 --> 00:41:02.050 Nadav Mary: And regarding scalability, so in inheritance, the more inheritance chains that we'll have, the more deep it will be, it will be harder to extend. And in composition, it scales better as the product grows.
258 00:41:03.580 --> 00:41:13.649 Nadav Mary: Basically, that's it, let's sum it up. So, when should we use inheritance, and when should we use composition? So, use inheritance when the objects share both common identity and behavior.
259 00:41:13.660 --> 00:41:33.229 Nadav Mary: So, our confusion at the beginning was that the hybrid and the gasoline and the electric vehicle shared the same behavior of the gas level and the battery level, but it didn't share the common identity, and this is why our first implementation didn't really fit.
260 00:41:33.620 --> 00:41:44.150 Nadav Mary: And use composition when your object needs functionality from another class, but it's not fundamentally the same thing as we've seen.
261 00:41:44.460 --> 00:41:45.260 Nadav Mary: Great.
262 00:41:46.180 --> 00:42:00.089 Nadav Mary: Let's go to the second part. In the second part, we'll not need neither the hybrid vehicle and the wireless chart, so I'll just delete it, so we'll have less code to look at.
263 00:42:00.440 --> 00:42:09.949 Nadav Mary: And let's say that now we want to add a new capability to our vehicle system, and is a capability of creating a report.
264 00:42:09.950 --> 00:42:24.159 Nadav Mary: So let's say that in the base behavior will print out the year and the model, and our inheritors, the gasoline and the electric vehicles, will print out the gas level and the battery level.
265 00:42:24.370 --> 00:42:37.299 Nadav Mary: in each of them. So we'll have a full report with the year, the model, and the specific parts of each, of each vehicle. So, what we can do is creating a function of a create report.
266 00:42:37.690 --> 00:42:44.689 Nadav Mary: And we'll print out the model and the year.
267 00:42:44.750 --> 00:42:58.420 Nadav Mary: And then what we can do is go ahead for our gasoline and the electric vehicles, and we can override, the createReport function.
268 00:42:58.580 --> 00:43:02.510 Nadav Mary: And first, of course, we'll call a super.createReport.
269 00:43:02.660 --> 00:43:14.069 Nadav Mary: And then we'll print out the specific part of the gasoline vehicle, which is the gas level, and we'll do just the same for the electric vehicle.
270 00:43:14.210 --> 00:43:31.050 Nadav Mary: And now one will print out our electric vehicle credit report, and we'll run that. We can see that we have the full report with the model, and the year, and the electric report. The electric vehicle adds its battery level.
271 00:43:31.250 --> 00:43:34.150 Nadav Mary: And when looking at that.
272 00:43:34.150 --> 00:43:48.019 Gabor Szabo: Nadav, sorry, sorry to interrupt you. Sure. There is a question now, could we consider using protocols? Would they add flexibility? Are they as easy to maintain in sort as well as in code?
273 00:43:48.870 --> 00:44:06.060 Nadav Mary: Yes, absolutely, we can use a protocol. I don't want to touch it a lot, but maybe I can share an example later in the chat, but absolutely, you can use a protocol in order to encapsulate some behaviors inside the protocol, and then your
274 00:44:06.060 --> 00:44:23.630 Nadav Mary: letting your inheritors go ahead and implement their specific… the specific behavior that you would like. I didn't want to go into protocols, because it's something that might be more specific to Python, and I wanted to explain
275 00:44:23.630 --> 00:44:31.829 Nadav Mary: the, the basic, patterns, agnostically, but, absolutely, yes. You can, also use, protocols and,
276 00:44:31.840 --> 00:44:37.299 Nadav Mary: Later, I can, I can share in the chat, implementation using protocols.
277 00:44:39.830 --> 00:44:40.510 Gabor Szabo: Thanks.
278 00:44:40.890 --> 00:44:44.200 Nadav Mary: Yes, thank you. Yeah, so,
279 00:44:44.400 --> 00:44:47.870 Nadav Mary: So, let's go back to the Curate report, so…
280 00:44:48.100 --> 00:44:58.469 Nadav Mary: So, we can already see that we're having some issues with that implementation. First of all, our gasoline and electric vehicles
281 00:44:58.600 --> 00:45:09.750 Nadav Mary: must call the super.createReport, because otherwise our… our report will look broken. We'll have only their specific parts, so right now.
282 00:45:10.160 --> 00:45:17.130 Nadav Mary: Our inheritors are controlling the basic behavior, sorry, for the create report.
283 00:45:17.780 --> 00:45:31.979 Nadav Mary: And calling super becomes mandatory, otherwise we're breaking the base behavior, and this also breaks the encapsulation of the base class of how the report will look like.
284 00:45:33.860 --> 00:45:52.699 Nadav Mary: And second of all, and even worse, what if our report, and let's go to the base function, what if our report will be more sophisticated, and not just the first line from the base class, and then second line from the inheritor? What if we'll want
285 00:45:52.710 --> 00:45:55.090 Nadav Mary: I had to create here the header.
286 00:45:55.280 --> 00:46:06.070 Nadav Mary: And then we'll want the body of the report, the specific part, and then in our… let's say even the header, the model is
287 00:46:06.440 --> 00:46:17.949 Nadav Mary: The model, and then in our footer, we'll want to print out our… the ear of the… of the… of the… of the vehicle.
288 00:46:18.160 --> 00:46:22.580 Nadav Mary: In this case, in our implementation, it will never work, because
289 00:46:22.710 --> 00:46:31.780 Nadav Mary: calling super will print out the header and the footer, and just then the specific part of our subclass.
290 00:46:33.380 --> 00:46:37.640 Nadav Mary: And this is where things, again, becomes more complicated.
291 00:46:38.670 --> 00:46:52.419 Nadav Mary: And in order to fix that, what we can do, is using the temp… it's called the template design pattern, in order to simplify our, infra code, our vehicle.
292 00:46:52.520 --> 00:47:02.249 Nadav Mary: code. And the idea is that we let the vehicle base class to define how the report should look like, structurally speaking.
293 00:47:02.700 --> 00:47:11.690 Nadav Mary: And our inheritance, the gasoline and the electric vehicle, will only deal and will add their specific parts to the report.
294 00:47:12.540 --> 00:47:17.790 Nadav Mary: So what we're going to do is keeping our createReport main function.
295 00:47:17.920 --> 00:47:22.609 Nadav Mary: And, our vehicle will call the create a body report.
296 00:47:22.970 --> 00:47:30.730 Nadav Mary: Which will be… which will be an abstract function, an abstract method.
297 00:47:30.870 --> 00:47:37.900 Nadav Mary: It, will be enforced, will be implemented by each inheritor.
298 00:47:38.030 --> 00:47:52.019 Nadav Mary: And then what we'll do is that in our gasoline vehicle and the electric vehicle, instead of overriding the create report, we'll override the create body report, and now we don't have any more to call to super.
299 00:47:52.280 --> 00:48:00.709 Nadav Mary: And then our gas zone vehicle will only have to complete its part, as we've said. And we'll do the same for the electric vehicle.
300 00:48:01.410 --> 00:48:06.249 Nadav Mary: Create a body report, and again, we don't need to call super anymore.
301 00:48:06.450 --> 00:48:19.039 Nadav Mary: And then we… when we run the program, we can see the exact structure that we wanted. We have the header, with the specific part of the vehicle, and then we'll have the footer with the ear.
302 00:48:19.730 --> 00:48:24.419 Nadav Mary: Perfect. And… yeah, let's go to the… back to the presentation.
303 00:48:25.980 --> 00:48:31.289 Nadav Mary: Yeah, so we just encountered what's called the cold super anti-pattern.
304 00:48:32.000 --> 00:48:34.430 Nadav Mary: So what is the cold superante pattern?
305 00:48:34.740 --> 00:48:41.200 Nadav Mary: Called super anti-pattern means when calling super becomes mandatory, when subclasses
306 00:48:41.210 --> 00:48:55.939 Nadav Mary: Must remember, as we've seen, calling super, otherwise our base functionality broke, because we didn't get a full report in our example. And as we've said, it also breaks the encapsulations, because subclasses
307 00:48:55.940 --> 00:49:04.909 Nadav Mary: could control the base behavior, and could, for example, not calling super, and then they could, control of how they report
308 00:49:04.920 --> 00:49:06.240 Nadav Mary: Will look like.
309 00:49:06.650 --> 00:49:20.430 Nadav Mary: And we've simplified that by using the template design pattern, which is a very strong and very good pattern for flexibility in our case. By the way, we could
310 00:49:20.700 --> 00:49:21.780 Nadav Mary: also…
311 00:49:21.910 --> 00:49:34.089 Nadav Mary: if we want even to make a more sophisticated template over here, so we can go ahead and create more abstract functions if we want to create a footer report, which is
312 00:49:34.090 --> 00:49:43.699 Nadav Mary: customed by the inheritors or anything else. We can do it as much as we want, using the template design pattern.
313 00:49:43.950 --> 00:49:58.690 Nadav Mary: And basically, what template design pattern gave us is encapsulating the structure in the base class, so we had the structure of our port in our vehicle.
314 00:49:58.830 --> 00:50:04.619 Nadav Mary: And we let the subclasses only fill their specific parts. In our case, it was the body.
315 00:50:05.040 --> 00:50:10.990 Nadav Mary: And we didn't need to call, to, to super anymore in the, in the subclasses.
316 00:50:11.780 --> 00:50:17.299 Nadav Mary: And the last thing is, when calling super actually becomes anti-pattern.
317 00:50:17.370 --> 00:50:21.290 Nadav Mary: So, in general, there's nothing wrong with a subclass.
318 00:50:21.330 --> 00:50:26.849 Nadav Mary: calling to, to, to super. It's something that,
319 00:50:26.880 --> 00:50:46.250 Nadav Mary: that the language is supporting, and specifically Python, and it's something that you can absolutely and you should use if it's something that you need. But when super becomes a requirement to your functionality, this is when it becomes an anti-pattern, because
320 00:50:46.250 --> 00:50:49.319 Nadav Mary: Calling super is not enforced by the language.
321 00:50:50.020 --> 00:51:01.270 Nadav Mary: And if it's not enforced by the language, so when you're not calling it, you're increasing the risk of mistakes, again, in case that calling super becomes a requirement.
322 00:51:03.440 --> 00:51:21.429 Nadav Mary: Basically, this is it from me, so we talked about… we talked about inheritance, and we talked about the download inheritance issue that we encountered, and we talked about composition, and we compared between inheritance and composition, and we just talked about the cold super anti-pattern.
323 00:51:21.430 --> 00:51:24.569 Nadav Mary: And we solved it using the template design pattern.
324 00:51:24.600 --> 00:51:36.160 Nadav Mary: But more importantly, I want to remind you the question that I asked you at the beginning. So, if AI writes code, do coding best practices still matter? So.
325 00:51:36.240 --> 00:51:49.269 Nadav Mary: I personally believe that coding best practices matter even more than before, because good code is not just code that works, it's code that is designed to evolve.
326 00:51:49.400 --> 00:51:59.070 Nadav Mary: Whether it's inheritance on composition or any other design pattern, the important part is not memorizing the rules. It's understanding when and why you should apply them.
327 00:51:59.100 --> 00:52:10.160 Nadav Mary: AI shifts our job from writing code into judging code. It becomes our assistant. And you cannot judge what you don't understand.
328 00:52:11.380 --> 00:52:15.489 Nadav Mary: That's it. Thank you so much. If you have any questions,
329 00:52:15.560 --> 00:52:35.260 Nadav Mary: I'll look at the chat now, and we can talk about it, and I shared over here my LinkedIn and my email, so you can just go ahead and connect me, and you can send me any message if you have questions afterwards, and I promise that I will answer all of your messages.
330 00:52:35.530 --> 00:52:36.380 Nadav Mary: Thank you.
331 00:52:37.860 --> 00:52:54.189 Gabor Szabo: Well, Nadav, thank you very much for this presentation. As I can see in the chat, there are no other questions, which is a little bit less surprising, because, like, 90% of the people here are from your workplace, so they are sparing the questions for later when they're going to meet you tomorrow.
332 00:52:54.190 --> 00:52:59.590 Gabor Szabo: But, still, if you have… if any of you have questions, then please ask now.
333 00:52:59.590 --> 00:53:04.250 Gabor Szabo: In the chat room,
334 00:53:05.200 --> 00:53:23.350 Gabor Szabo: I was wondering if I have any questions, but we can talk a little bit about the AI, actually, because you are sort of in the position, as I guess, that AI will write your code, and you will still accept the pull request from AI, or whatever way you integrate your code.
335 00:53:23.350 --> 00:53:26.699 Gabor Szabo: And at one point, you might need to read your code.
336 00:53:26.700 --> 00:53:42.710 Gabor Szabo: the code, that's sort of your assumption. As I understand, many people think that that's not going to be the case anymore, that we are just telling the AI to rewrite it, and rewrite it, and improve the
337 00:53:43.070 --> 00:53:48.339 Gabor Szabo: Features of the program without caring what is underneath.
338 00:53:54.200 --> 00:53:59.440 Gabor Szabo: I guess I was just talking, so I can give the opportunity for people to ask questions, but they don't…
339 00:53:59.440 --> 00:54:00.360 Nadav Mary: Yeah, yeah.
340 00:54:00.550 --> 00:54:12.060 Nadav Mary: Yeah, so I personally, see AI as my assistant, and not necessarily owning my engineering decisions.
341 00:54:12.130 --> 00:54:25.309 Nadav Mary: as you can see, it sped up my coding. If I had to write all the code by myself, it would probably take me, in the best case, twice then it took.
342 00:54:25.460 --> 00:54:36.180 Nadav Mary: But still, I'm the one who's responsible… responsible about the code, and I'm the one that's responsible to understand the feature.
343 00:54:36.650 --> 00:54:42.049 Nadav Mary: And the correctness, and understand the future of my product.
344 00:54:42.310 --> 00:54:48.689 Nadav Mary: And this is the reason that, again, coding best practices is important, and building,
345 00:54:49.540 --> 00:54:55.120 Nadav Mary: code in the right way is important, because if we'll not write
346 00:54:55.200 --> 00:55:10.149 Nadav Mary: the code in the correct way, we might deal and let, of course, AI deal with technical debts instead of going forward and building new features and new capabilities to our system.
347 00:55:10.270 --> 00:55:13.179 Nadav Mary: And so this is my two cents about that.
348 00:55:14.050 --> 00:55:20.460 Gabor Szabo: Yeah. By the way, just as a last note, it would be interesting to have a…
349 00:55:21.430 --> 00:55:29.399 Gabor Szabo: presentation, or a series of presentations, or a series of people presenting, how each one of them is using AI to write code.
350 00:55:29.580 --> 00:55:48.060 Gabor Szabo: what are the types of the ways of people? It's just a side note to you, and to all the people here who are here, and all the people watching the video. As I see, there are no questions, so just let me thank you, say thanks again for the presentation.
351 00:55:48.060 --> 00:56:00.540 Gabor Szabo: And for all the people who… Thank you. …who were here, and if you're watching the video, then remember to like the video, and follow the channel, and below the video, you will find links to,
352 00:56:00.540 --> 00:56:11.420 Gabor Szabo: the contact information of Nadav, so you won't have to copy it from the screen. And if you are here, the people who are here, feel free to stay
353 00:56:11.530 --> 00:56:25.979 Gabor Szabo: after the recording is stopped, and we can continue speaking, even though I know that most of you can meet him. You're going to meet tomorrow in the office, but those few people, especially those few people who are not.
354 00:56:26.020 --> 00:56:32.729 Gabor Szabo: You're welcome to stay and chat a little bit more. Thank you very much again, and goodbye!
355 00:56:33.160 --> 00:56:34.040 Nadav Mary: Thank you.