A Simple & Effective Way To Improve Python Class Performance

There's a very simple way to improve Python performance of your code. And you know what's so nice about this performance improvement? It also nudges you to use good Python software design practices - it's a win-win!
The code I worked on in this episode is available here: github.com/ArjanCodes/2022-slots.
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👀 Code reviewers:
- Yoriz
- Ryan Laursen
- Sybren A. Stüvel
- Dale Hagglund
🎥 Video edited by Mark Bacskai: / bacskaimark
🔖 Chapters:
0:00 Intro
0:50 How classes work in Python
2:00 Descriptors
2:46 Basic class example with the dict dunder method
3:53 Using slots
5:02 Slots performance test
6:07 Using slots with dataclasses
7:19 Slots performance test #2 (with dataclasses)
8:00 Why are slots not used by default?
8:39 Slots limitation: mixins and multiple inheritance
10:23 Slots limitation: dynamic attributes
11:25 Final thoughts
#arjancodes #softwaredesign #python
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[@ArjanCodes]

💡 Get my FREE 7-step guide to help you consistently design great software: arjancodes.com/designguide.

[@cychoboy]

Slots can also help you avoid certain types of bugs. For instance person.addres = "abc" becomes an error because "address" was misspelled. Vanilla classes will accept this input without any error leaving you to figure out why the address field wasn't changed as intended.

[@foji-video]

that I think is actually the main advantage when building serious applications

[@lawrencedoliveiro9104]

If you have read/write properties on a class, specifying slots is a very good idea.

[@SkyOceanNet]

I actually had that error inside my code for such a long time undiscovered. Recently I found it while reforming the code. Now I'm using slots and it can prevent that kind of mistakes. Thanks to Arjan and Edmunds!

[@Mr1995Musicman]

This is a great feature. Dynamic members is like loose typing: it sounds great as a beginner developer, but as a more experienced developer it's more often a headache

[@arpitkumar4525]

Even as a experienced dev, dynamic attributes and pretty much non existent boilerplate code seriously helps in prototyping or testing out risky features(risky in terms of feasibility). But other than that of course these should be avoided like the plague

[@Sam-qn6hl]

Amazed that nobody has questioned using the lower bound rather than an average metric, or plotting the distribution of the different runs. It's not clear that a lower minimum translates into general better performance in most cases, especially a "20%" difference. Having said that, this was an interesting video. Might run some of those tests myself.

[@isaacwolf2806]

Same thing I was thinking! Typically I like to see min, mean, and max. And if I'm trying to convince a coworker my way is better then I just take the best one. 😁

[@fjolublar]

the lower minimum is the most accurate measurement to take

[@rafarios50]

@@fjolublar why is it the most accurate?

[@artyomvancyan2000]

It is nice to see new videos about python but it's coming unactual more as there are a bunch of video curses about python. I very like your videos about project architecture and the unique code examples that you were using. I would really like to see in your channel videos about UML diagrams, project file structure, documenting packages and modules, design patterns that you haven't talked about them yet, etc. Thanks for your job.

[@PeterSeres]

I second the opinion that the most interesting videos are that teach us how to reduce coupling in the code by using design patterns and how to make python projects that are scalable.

[@hanabimock5193]

Totally agree on that. Also if performance is a problem, just avoid python.

[@ArjanCodes]

Thanks & no worries - there will definitely be more of those videos in the future.

[@jacksonarnold27]

Yes!! Project structure, program flow design, design patterns, etc would be great!! Same with UML stuff, I’d love some in depth videos on any of these

[@chaddrobertson5805]

I was recently told about slots on an SO question that I'd answered, and was quite confused by the concept until now. This was a fantastic explanation - thank you! A big +1 for touching on inheritance (was my largest concern as I was watching).

[@henrikholland1730]

Great video as always. Love the new studio set up.

[@_.gray._]

Loving the new setup! This explains slots really well, and I might just remember to use them next time I write a class haha.

[@willemvdk4886]

Congrats on the new studio/office, Arjan! Looking good. Good to see the contents don't suffer the even better look. Still very informative! Love it. Kappertje gepakt trouwens?

[@q2kq885]

Dataclass is truly a powerful structure in python. I'm really looking forward to learning more tips and tricks to make the python code faster. This tutorial is helpful. Thanks a lot!

[@EngHassanIbraheem1998]

You have a fantastic skill in choosing topics. Keep it up.

[@CornishMiner]

I'm liking the new setup Arjan. Super clear video and great sound.

[@steshinanton]

The videos are amazing! I like the way you explain things. It is easy and fun to follow. I always find something useful even if I know the topic and recommend your videos to my colleagues because they are so informative. The way you present inspires me when I do my presentations. The new setup is very nice!

[@casperschutte2516]

Thanks for the videos. They are always super interesting and very practical

[@fuadpalchayev7269]

Thank you! Very informative👍

[@malteplath]

I can see that you are proud of your new studio/office - and you should be! One aspect of inheritance with slots that you didn't mention, and that I am unsure about: how do you add new attributes in a class that inherits from a class with slots? Do you have to declare __slots__ again in the subclass?

[@sasha297603ha]

Great new studio and very interesting topic. Well done

[@sami3592]

Nice video. I also like your new setup. Your explanation of the topic always best. Thanks man.

[@zacharyAbresch]

Looking stellar mate, sharp looks to match yer words!

[@obsidiansiriusblackheart]

This is such a fantastic video and the fact that it's completely free is astounding!

[@flightmansam]

Fantastic video. I’m gonna use slots for sure! Also yes, I love the new look. Enjoy your week!

[@Vdherrlichkeit]

Again. Great content Arjan. Highly appreciated

[@MaksimKupfer]

Really insightful my friend, and great pace as well! Looking forward to following your content.

[@ArjanCodes]

Thank you Maxim, glad you liked the content!

[@nsontung]

Thank you so much, Arjan, great lesson. It improved my code performance a lot.

[@ArjanCodes]

Glad you liked it!

[@Swissfonk]

Love your new Studio.

[@ajflorido]

Cool video, a very good explanation indeed. And a really cool recording setup :D

[@jpconstantineau]

Great video! I wonder if micropython and circuitpython support slots at all. Python on microcontrollers can use all the performance help and this is something most people wouldn't even know about.

[@anhnguyenuc6543]

Thanks for your video. That's really what I needed

[@davidlinesq]

Love the new recording setup! Thanks for the content and hope you get to 100k subscribers soon.

[@ArjanCodes]

Thanks David!

[@TechieGuy82]

Superb as always. Thumbs up

[@jakob1379]

Nice video! A great way to better show the value of variables is with 'from rich import print'. It automatically highlights types and emphasizes structure.

[@wowzers94]

I dig the new set! And thanks as always for the python tips!

[@dhruvakashyap]

Amazing new setup! Great video as always!

[@ArjanCodes]

Thank you!

[@mahmudulhassan9043]

Thank you very much . i love all of your tutorial . it helps me lot to improve my skill .

[@ivolol]

I think you could add a translucent rectangle code graphic inset under the shelf light or something, on the left at 1:00 that could help show the code structure of the very things you're talking about, would work really well

[@heljhumenad]

This is so much informative especially on perf of py classes

[@PedigreeGuitars]

Great video. Always learning with you. The new setup look great!!

[@ArjanCodes]

Thank you Pedro!

[@jonathanheadley2729]

the setups are really nice! excellent work.

[@ArjanCodes]

Thank you Jonathan!

[@Michael201078]

Slots - very useful think. Thank you for the explanation.

[@pthube]

Thanks for sharing this cool feature

[@jakesurrett3518]

Sweet new set! Just a little feedback: I would love to see a little bit of graphics/illustrations/diagrams sprinkled in the explain-to-camera sections. When there is a visual complement to the topic/explanation at hand I just can't help but feel more engaged in the discussion. Fireship on KZbin has mastered this technique in place of appearing on camera at all (which I'm certainly not suggesting). SciShow is another excellent example of this technique in action. I suppose news broadcasts had this figured out from the start. Anyhow, food for thought at least and thanks for another great python video.

[@ArjanCodes]

Thanks for the suggestion Jake, I agree that would be helpful!

[@alilee4505]

Hey Arjan, congrats to your new setup! Looking forward to achieving 100k subs 👍

[@ArjanCodes]

Thank you Ali!

[@PawelOlas]

the new backgrounds and cameras you use are very nice. pro!

[@ArjanCodes]

Thanks Pawel!

[@ZeZa1515]

Really liking the new setups! Your face in the coding setup had a lot of shadows on it though, so it wasn't very clear

[@cryptosimon9529]

great setup!

[@unusedTV]

Audio has a bit more echo than in the past, in the first two setups. Coding setup is fine.

[@niksen3300]

Hey Arjan! I have been watching your videos and i have a question that i could not find a clear answer to. Is there a reason to NOT use dataclasses? It really seems to be the cleaner approach to managing and writing your classes but are there reasons to pick normal classes over them? Great content by the way! Loving your channel.

[@holographicsol2747]

thank you that just helped a lot as i remembered watching this a while ago and came back to refresh my mem!

[@ArjanCodes]

Glad to hear you found it helpful!

[@holographicsol2747]

@@ArjanCodes awesome

[@MagnusAnand]

Fantastic video!

[@bryangalindo]

Nice setups!! The changing light in the first setup was a little distracting, but the other setups were perfect. Also, thanks for sharing how slots work, its limitations, and providing a real-life example of a tool using slots. Very informative!

[@dedekind1982]

Thanks! Find ways to keep delivering value like this. Thank you

[@ArjanCodes]

Thank you, will do!

[@BartKevelham]

Awesome new setup Arjan! If I'm very nitpicky (but that's not a thing I would ever be) then I'd say the programming view could use a bit of fill light for the right side of the face. But quite an awesome step up already. And besides that, another excellent video. Keep it up!

[@ArjanCodes]

Thanks Bart! I agree & it’s already fixed for the next batch 😊.

[@demasjaring5435]

Awesome camera quality 👌

[@ArjanCodes]

Thank you!

[@lungenbrotchen]

Thank you for your videos. I learned a lot from them and I also like the entertainment factor of your videos.

[@ArjanCodes]

Thank you so much - glad to hear the videos are helpful to you!

[@kenhaley4]

Very nice...as usual. It seems like another advantage of using slots would be to catch spelling errors in your classes' attribute names. For example, without slots, the statement myPerson.namee = "Joe" would work fine, but myPerson.name would not be affected. But using slots, the statement would raise an error: 'Person' object has no attribute 'namee' which would let you find and fix the spelling error much sooner.

[@python_byte]

Awesome, amazing way to create a well readable and secure code

[@theherk]

Dang, That set looks superb.

[@christianforster3408]

Hi Arjan, love your videos! Just one little note. Wouldn't it be a better measure to use the average performance, than the minimal one? At least I'd be more interested in the average difference in performance ;) Cheers!

[@valenciawalker6498]

Thank you

[@dqalombardi]

I felt so certain that this was just going to be clickbait but honestly it just makes so much sense and I can't believe I didn't know about this before now.

[@gshan994]

I like dat you are trying to be like other youtubers wid d lights in BG n all. But i subscribed your channel solely for the knowledge u share. Yes, the setup is good, but honestly I loved your setup with a straight up facing camera.

[@jimboppin2461]

great vids, just heads up new sound is a little boxy/tinny 👍

[@Hubert4515]

we love the new setup! :D

[@ArjanCodes]

Thanks!

[@newoptionz]

Thanks @ArjanCodes. Unfortunately I have not yet seen your free 7-step guide? I have signed up at the link you indicate and even purchased some of your courses by I haven't found this elusive guide, lol. Please help.

[@ardaakdere]

Really cool and energetic also!

[@vlntsolo]

Thanks!

[@ArjanCodes]

Thank you Valentyn, glad you liked it!

[@jonathan3488]

Hi, great video. Does this work the same for private and protected attributes?

[@SarcTiann]

excellent explanation

[@ArjanCodes]

Glad it was helpful!

[@jimmyf.x.9526]

So amazing I want to use the f word! Fantastic!!!

[@enigq]

May I just say that I love the graph monster in the background?

[@Rodrigo-rq1dx]

The sofa set (0:54) has a lot of potential for you to add animations to explain what you're talking about. Like sketches/code snippets that illustrate.

[@ArjanCodes]

Good suggestion! I definitely want to explore animations to improve the clarity of the videos.

[@PracticalPillow]

Honestly, this is the first time I see slots, but I have a question. Does performance grow for get, set and delete evenly or some of them has a bigger contribution? Thanks you for the video!

[@Rebeljah]

I like the new set!

[@Claxiux]

Chief, that lights thing on your left is a bit distracting (setup 1). Thanks for the video!

[@ThomasConrad]

Very informative. I honestly didn't know this. Free performance increases are the best performance increases.

[@spell105]

There is no such thing as a free lunch, it's worth knowing about the limitations of slots.

[@gheefop]

no hoodie? Arjan I think this strapping professional has taken over your channel 🤣 new sets look great

[@saeedgnu]

In Go, you can "compose" several structs in a bigger struct, and get convinience of multiple inheritance, without inheritance at all. But in Python, sometimes the only way to make your class smaller is to use multiple inheritance. I think in some ways, Go is a better Python than Python (based on the Zen of Python).

[@robertbrummayer4908]

Hi Arjan, great video! I also like your new setup. However, as also other commented, the audio seems to be worse than before.

[@ArjanCodes]

Thanks! The audio could indeed be better, still have to tweak the new setup a bit, but we’ll get there.

[@castares]

Good video, thank you for your content. But, shouldn’t you use mean instead of min when calculating performances? Those mins could be outliers

[@rajat971]

@arjan - Should we always user dataclasses even if we have a lot of business centric complex methods in the Class or should be only use dataclass for saving data in class and using simple get set methods?

[@MrDowntemp0]

Is it possible to use descriptors for validating attributes in a class that uses slots?

[@Burbinox]

What about the case when we will have a list object as a slot? Does that make sens?

[@callumfleming8662]

Like number: 660 great video, didn't even know slots existed! thank you!

[@pedroazambuja132]

Damn looking good man 🕴

[@djangodeveloper07]

high quality content about python on this Channel. No Doubt in it

[@ArjanCodes]

Thank you Ahmad, glad you like it!

[@ac130kz]

I think attrs is such an awesome thing, it is faster than dataclasses, has validation, extra features, and the slots are enabled by default!

[@nocodenoblunder6672]

What is attrs?

[@burnere633]

h4X0r Arjan to corporate Arjan. Also changing lights in the background is a bit distracting.

[@StevenMartinGuitar]

The shirt seems a little formal :D but the new recording setup looks dope!

[@ArjanCodes]

Haha, yeah I thought let’s change things a bit for fun. Next time, back to hoodies & simple shirts 😁

[@shamaldesilva9533]

Damnnnn that background 🤩👏👏👏

[@ArjanCodes]

Glad you like it!

[@MarcelSchliesser]

Danke!

[@ArjanCodes]

Thank you, Marcel!

[@janHodle]

Thank you! Your content belongs to the better ones here on KZbin!

[@danzobisk2743]

Hello any video about Python Guard clauses please

[@kalagecko77]

Thank you Arjan! I using classes in a raspberry pi 4 to perform face tracking with 2 servo motors. Since I am using python 3.9 with no slots attributes for dataclasses, I am using the classical class definition with slots. Unfortunately I couldn't see any improvements. Without using classes or functions I've got an incredible FPS rate. I've tried to switch to python 3.10 using pyenv and venv. Unfortunately I am facing some dependency problems with a library (libcam) that is installed with apt-get install instead of pip3. So I cannot run the program with python3. 10 to test performance. Maybe you have a good hint here for solving this dependency issue. Thx

[@jusce17]

Performance wise, if we use data type when declaring variable (e.g a:int = 10), does it anyhow improve the performance ?

[@gshan994]

I mostly use python for aws cdk. And for architectural diagrams i use plant uml diagrams.

[@johncongerton7046]

The best tutor of all

[@ArjanCodes]

Thank you for the kind words, John!

[@ahmadkhaled4751]

Thank you Arjan for your brilliant content, I'm a fan of your Midlife-crisis looking thumbnails.

[@marcioneto3016]

The new setup is looking great! Great video, as usual.

[@JoaoSantos-lv4rc]

it is a cool setup. (imo)

[@grzegorzryznar5101]

Hello Arjan. Could you tell about different way to implement class which inherits over employee and person? I agree that multiple inheritance may be bugggy, but how to solve that in a clean and efficient way?

[@VileVillian]

Answering as a sr dev here - try thinking in terms of composition instead of inheritance. Inheritance implies an "is a" relationship. A Square "is a" Shape. Composition implies a "has a" relationship. A vehicle "has a" steering wheel, brakes, and headlights. Its very rare that you will find yourself with the need to describe W "is a" X, Y, and Z. Hope this makes sense. There are others who can explain it way better - just search "prefer composition over inheritance" - it is a well-known axiom amongst experienced OO developers. Edit: As a nice side effect to using composition over inheritance, you'll find your unit tests easier to implement because you'll be in a good position to leverage dependency injection and provide mocks for the dependencies rather than having to mock any dependency chains of your parent class(es).