The way you progressively take the viewer through the level of abstraction is one of the best parts of this, and many of your videos.

@pramodjingade6581

Жыл бұрын

Yep, exactly!

@klmcwhirter

11 ай бұрын

Agreed. While I really enjoy James Powell videos like the one below, @ArjanCodes just presents things in a very fluid manner. kzread.info/dash/bejne/lX-EzrKDqbTYpJc.html My colleagues were lost with the content presented in that James Powell video. But I hope that no one was lost with what @ArjanCodes presented in this one. Good job @ArjanCodes! Thank you.

I've consumed a lot of programming content recently and this channel is one of the best I've seen. Well produced, professional and perfect pacing. Even the occasional joke!

@ArjanCodes

Жыл бұрын

Thanks so much!

Hi, Arjan! Can you make a video about "module/package structure" in Python? For instance, using a project as an example, what classes should be grouped together in which modules/packages (nomenclature, subjects, etc). Regards!

@ErikS-

Жыл бұрын

I totally support this idea! For me it is still a bit of a mystery how to BEST create a library/package from your own files...

@kevon217

Жыл бұрын

^

@Fritz0id

Жыл бұрын

Yes x1000. While the syntax isn’t too hard to get my head around, best practices is always difficult to get a handle on. And most info on web is for open source projects. It’s actually quite difficult to get an idea of how to robustly share internal packages with the rest of your team in a non-open way.

@manuelstausberg8923

Жыл бұрын

+999 to this :)

@yasamankarimi8219

Жыл бұрын

agreed. i'd like to see that too

".. a pain in the class.." 🤣 Added to my sayings... Thanks Arjan!

I cannot overstate how well you described the decorators in every aspect! Great work!

Great stuff. I have never understood decorators... Until now. It was so nice how you showed step by step how it works. I thought decorators were only python thing but now I see its a general concept doable in all languages

@ArjanCodes

Жыл бұрын

Glad you liked it!!

@MJ-xl5jz

Жыл бұрын

​"@ArjanCodes" It even works on KZread. I'm just trying to wrap Arjan's Glad-you-liked-it to decorate my comment.

This is just gold on youtube. So many junior devs don't understand decorators in Python, and think of them only as this "Magic" that you put on top without understanding anything. Thank you, Arjan.

@ArjanCodes

9 ай бұрын

Thank you!

Really nice video! I discovered Decorators in my new job (C++), but we use the traditional pattern because we can change the order and list of them by the DI configuration tool or inside factories. Amazing how things like anticipation, sync or cached operations are decoupled from the model object.

One of the best channel for learning python best practices. Thanks alot Arjan!

@ArjanCodes

Жыл бұрын

Thank you, Tim, glad you find the content helpful!

THANK YOU 😊 Wanted something on this topic and just in time for lunch break today ! Gonna use it immediately

This dude i can tell came from Java/C++ world he mastered OOP - this is a great for a seasoned developer. Thanks bro.

It's literally like you're spying on my current challenges at work! There's a heavily nested decorators function that is being used and this has cleared things up a lot! Thanks so much, keep going with the great work!

@ArjanCodes

Жыл бұрын

Thank you and will do!

I have watched a few videos on this topic and you explained the best. It's so easy to understand with some background (classic decorator pattern in OOP and then how Python gets it done). Thank you.

@ArjanCodes

Жыл бұрын

Glad it was helpful!

I started watching recently and I have been pleasantly surprised by the quality of your content. There is one caveat, I think, to using the @decorator syntax of python and that is if you need to provide different parameters to the wraper function in different moments. Since the decorator is set at the beginning of the definition of a function, you would either define a function multiple times with the decorator with updated parameters, or use one of the other ways to use a decorator as you showed in the video.

I know the decorator pattern from top of my head, but I use python decorators so rarely I have to re-learn them every time :) Another good use case for decorators is error handling. We catch different exceptions in a web app on different layers and turn them into http errors. But overall decorators are a niche thing.

Omg, thought how to combine music with your videos - and here it comes. Much easier to switch from coding to learning now, nice feature:)

Great video. For anyone wanting to use the with_default_logging decorator, be aware of a potential issue. Most likely, the logger object will have the name from the module where it was instantiated. If you import it via decorator into another module, it might get confusing where the logging call actually came from because the logger name can be mistaken for the module name. I definitely had the issue in the past and it took me a while to figure out what was going on.

I definitely agree that wrapping logic in decorators makes code harder to read, but I love using them to register handlers, like how Flask defines routes. I use it like that all the time for event handlers, and I just think it makes the code super easy to read and understand. Love your videos, so happy to see someone else who loves Python as much as I do 😁

@sadhlife

Жыл бұрын

BTW, flask's decorator functions also return the original function unchanged. So even though a function is a flask route, you can call it just like a regular function if needed. Flask's types were broken regarding this fact, and I had to fix them sometime last year.

Welp. I guess I now know exactly what I need to rewrite part of a work project. There's some complicated and annoying interdependencies that I am not a fan of, but I hadn't figured out how to solve it. Also, thanks for explaining something that as far as I could tell were just magic!

@ArjanCodes

Жыл бұрын

You're welcome, Marie! :)

Turtles all the way down. Glad you mentioned the "harder to read" downside. Excellent presentation of a fun tool.

@ArjanCodes

Жыл бұрын

Thank you, glad you enjoyed it!

I liked the first part of your tutorial. It reminded me how I used to decorator before java 1.5, and instantly boosted my learning speed.

@ArjanCodes

Жыл бұрын

Thanks for sharing!

In my previous work, VW group, decorators were used to decorate classes and decorators created instances of classes that we wanted to use in the class. So they were some kind of Factories for other classes. I had no idea how that worked at the time :)

Just way awesome than any video. Thank you loads Arjan ❤

@ArjanCodes

Жыл бұрын

Thank you so much 😀

Great video as always, I use the built in decorators but Ive never reach the point of making my own. It looks awesome but in practice I feel its a bit convoluted as an end user. I will definitely will try them out now. Thank you for the great video.

@ArjanCodes

Жыл бұрын

Glad you liked the video! 😊

I wrote a decorator for a web application once that enforced authorization. It would get the user session object from the coroutine context and verify that the user possessed the permissions defined in the decorator call. e.g. @secure('write_permission') Great videos btw! I would appreciate a video on decorator classes. I've always found them very hard to understand how they work and what the pros/cons are. Oh, and a video on the coroutine context! Thanks!

JIC: we also can implement decorators using class with `__init__` and `__call__` method (`__init__` for parameterizing and `__call__` for applying deco to func of class) And in addition we can decorate not only functions but classes as well

Thanks for the lesson Arjan. Very well done.

@ArjanCodes

Жыл бұрын

Glad you liked it!

I came for the high quality and well thought out content. I stayed for it too. But I loved it for all of the glorious puns. :D Thank you for the education and the puns. Both are much appreciated!

@ArjanCodes

Жыл бұрын

Glad you enjoyed it!

Amazing content! Thanks so much for sharing that.

Thank you so much for the videos! Could you use more visuals (drawings) before writing the code? I guess if you draw what you are trying to build before building it, this will deliver the message perfectly

This is the most practical advise on decorators i've ever seen or heard.

@ArjanCodes

Жыл бұрын

Thanks!

I'm learning from you a lot. Many thanks!

@ArjanCodes

Жыл бұрын

My pleasure!

Easily the best presentation on decorators I’ve ever seen. 👏🏻

@ArjanCodes

9 ай бұрын

Wow! Thanks so much 😊

cette chaine est une mine d'or ! 🧡

One of your best videos yet

Decorators are truly a double edged sword. I have used them in the past to pass on a database session through multiple layers of controllers in a rest application. The decorator took ownership of the session and decided when to open / flush / commit / and close the session. It also added some parameters to every controller function in order to implement some security features. It worked wonders for our project as even after countless controller calls a session could seamlessly revert to an old state if an error occurred and controller functions were automatically secured, but to this day it confuses some developers when working with it, because not everyone understands python decorators well. Though I still stand to that design choice today.

Exactly the video I was looking for. 🎉🎉

@ArjanCodes

Жыл бұрын

Glad I could help!

thanks this super insightful guide! much appreciated

@ArjanCodes

Жыл бұрын

Thank you!

My python code always looks like it's straight out of the 90s and yours reminds me of something from another time completely. Definitely should brush up more :)

I had a hard time understanding decorators in my high school days. Never created my own, but I think I might have to reconsider now

great video, thx a million, making me revisit those ideas, i tend to forget ;)

@ArjanCodes

Жыл бұрын

Thank you, glad you liked it!

Thanks for the excellent and easy-to-follow explanation! Brilliant teaching :)

@ArjanCodes

3 ай бұрын

I'm glad to hear that the video was helpful :)

Liked the video when I saw the like video button light up as soon as you talked about it. Nice!

I recently implemented a version elevator system using decorators. The version elevators were just simple functions that take in a config object and modify it in-place updating it to the next highest version. The decorators were needed because some versions needed multiple mending functions due to inconsistend versioning plus we also had some functions that were just there to provide some convenience options in the configs. As such, the decorator would take the version for which the mending function should be applied as an argument or None it is a convenience thing. The decorator would then take care of adding logging and registering the mending function. Now, outdated configs can be updated by just running all the version escalators on it in the given order, e.g. if the config is version 3 and the current version is 5 it would be 3->4->5 and then run all of the convenience stuff. I think the decorators make the code quite tidy since all you see is really only the migration logic. I would recommend using the class-based approach with `__call__` when you want decorators that take arguments though. I find them easier to read than three nested functions and it makes dealing with defaults easier as well.

Realized now that Arjan codes is one of the only channels that when you ask for a like i actually stop and like the video. Thought goes like: "that's so useful, it really deserves a like" hehe btw: i would like to see your deep dive on the import system ...

@ArjanCodes

Жыл бұрын

Thanks for your support! I noted your suggestion :)

This channel has the most useful python tutorials.

I just started getting into decorators, and this is such a comprehensive guide on what the hell a decorator is, thank you so much

@ArjanCodes

Жыл бұрын

You're so welcome!

Great video, I use decorators all the time, but only the cases as you show in the video benchmarking and logging start of end of a method call. Never use multiple decorators, if i need both timing and logging, i create a single decorator that does both

@dane2565

Жыл бұрын

this is not always the case. there are quite well known frameworks which use stacked decorators frequently as middleware.

@dane2565

Жыл бұрын

also order matters. if you have a number of decorators, do you want to write a decorator for every combination of them?

Easy to follow and very helpfull!

@ArjanCodes

Жыл бұрын

Great to hear!

Huge pain in the 'class' haha! Very nice!

One of the best python video makers ever.. Keep going sir.. 😁 I have been following since so long, I'm a machine learning engineer and I come here once in a while, and always watch the latest ones to be sure my python skills are state of the art 😎

@ArjanCodes

Жыл бұрын

Thank you so much for your support!

Simply an amazing video 😌 Thank you.

@ArjanCodes

8 ай бұрын

Glad you enjoyed it, Diego!

An amazing tutorial! Thanks

@ArjanCodes

Жыл бұрын

You're welcome!

As a functional programmer I love the functional decorator, combinators are good.

For me the option that makes most sense is to use functions in the decorator design pattern. That way, if you're benchmarking code (say, in a jupyter environment) you can called the decorated functions of methods, but when you're deploying the code in a script that needs to run for hours and no one will look at, you can call the function without the decorator, thus leaving out a bunch of logging and calls to perf_time()

Finally understand how decorators work in detail

I really like functional programming and specially haskell. I often try to see how to reproduce haskell behavior in python for fun (and sometimes profit). Decorators were the obvious choice to implement currying. The not so obvious choice used by functools.partial (class) is much better, but requires more work to work properly.

Thanks, i like the path from classic patter to python’s decorator style.

@ArjanCodes

2 ай бұрын

Glad you like it!

Thanks. It is a great video explaining how decorator works. It is a good feature of dynamic programming language.

@ArjanCodes

6 күн бұрын

Thank you for the kind words! Glad you liked the video.

Thanks Arjan!

@ArjanCodes

Жыл бұрын

You’re welcome!

Superb, like always.

@ArjanCodes

Жыл бұрын

Thanks so much!

I was hoping that you would talk about ParamSpec near the end to be able to preserve the argument types of decorated functions for better autocomplete :)

One notable case where I built my own decorators was to build a mini-ETL framework. I was using decorators to inject data validation checks pre and post transformation steps. Also reused the @nested_dataclass trick someone posted online to be able to create dataclasses with nested dataclasses members off of unpacked dictionaries.

@manuelstausberg8923

Жыл бұрын

Do you have a link for that by chance?

Great Video Arjan. How would you implement an async decorator for async functions or a decorator that can be used on both sync and async. Still found a solution that "feels" right

I was trying to accomplish a decorator in a class and couldn't make any sense of it until i saw this video. Arjan explains the best and most generic way of achieving a decorator.

@ArjanCodes

9 ай бұрын

Thank you so much!

Absolutely great video

@ArjanCodes

6 ай бұрын

Thank you so much!

One more fantastic python guide. ❤️ You make it easy to learn. Are you also going to tackle another programming language, like javascript? Or will that hurt your KZread algorithm too much?

@ArjanCodes

Жыл бұрын

I expect mixing programming languages will hurt the channel. But I might start another channel in the future that focuses on a different programming language.

I use decorators mostly for testing and debugging. Having a dedicated decorators for benchmark and logging produces less clutter and I can simply remove the decorator if I no longer need it. I also use my own @NOT_IMPLEMENTED decorator to automatically raise a NotImplemented exception and print message to the console, so I don't have to write the code manually in every function over and over. Otherwise I try to stay away from decorators (unless it's property, dataclass or pytest fixture).

Thank you so much for your hard work and the effort you put into your channel. Great video!!! Quick question/ idea for another video Could you describe the difference between Decorator and Proxy Design patterns? Thanks in advance!

@ArjanCodes

Жыл бұрын

Great suggestion!

I usually use the decorators from packages, I didn't had the need to create stuff for myself.. but watching this video, I see there is a lot of small stuff I do a lot in my code that could be an decorator.. just low level stuff like error handling and logging..

Very good!

@ArjanCodes

Жыл бұрын

Thank you!

powerfully awesome

Love it!

@ArjanCodes

Жыл бұрын

Thanks!!

I notice you only talked about function decorators, not class decorators. They have their uses, too. I think the most extensive use I have made of custom decorators so far has been in my DBussy package, a pure-Python wrapper for libdbus. The information defining the D-Bus interface to a Python class is specified via a function decorator on each Python method implementing a D-Bus interface method, with a class decorator to tie it all together. Then when you register your class to receive messages, the dispatch mechanism knows how to decode incoming D-Bus method calls, convert the arguments and dispatch to the appropriate Python method. As a bonus, this same information is used to automatically generate the D-Bus XML introspection format, when another D-Bus peer sends you the introspection message. And conversely, when you introspect another D-Bus peer, this info is used to dynamically generate a “proxy interface class” -- a Python class whose methods simply send the appropriate D-Bus messages and return the responses.

The most useful tip with decorators especially in-case where a decorator handles input, for example in authentication the best possible way to handle invalid input is to raise an Error : raise UnAuthenticatedError(message) then handle the error else where on your code, any other means of handling invalid arguments or invalid credentials is bound to cause problems with Flow.

@JusticeNDOU

Жыл бұрын

for example if you handle invalid arguments by passing along a variable or credentials , then if they are invalid and you forget to handle the case where the credentials where invalid in the method or function in which the decorator is being used, you may not find this bug... straight away,

@ArjanCodes

Жыл бұрын

Yes, good points!

Hey, Can you make a video about the difference between decorator and proxy design patterns

OH MY GOD IT FINALLY MAKES SENSE

This is extremely interesting, I am working on a Flask 2.0 project and would like to know if you have any videos on Flask. Search did not find anything apart from GarphQL VS Rest. Thank you.

@ArjanCodes

Жыл бұрын

Haven't done a video on Flask, but soon a video will come out on FastAPI.

@aryan6536

Жыл бұрын

@@ArjanCodes I look forward to it, thank you very much.

Brilliant video. May I ask which IDE is that - that run button and auto switching to terminal is quite nifty.

@ArjanCodes

Жыл бұрын

Thanks! I'm using VS Code.

For logging I use loguru - a neat little library that saves me some time

22:38 You shouldn’t have bothered with functools.partial. Just do with_default_logging = with_logging(logger)

He is back!!!

Danke!

@ArjanCodes

8 ай бұрын

Happy you enjoyed the video, Andreas!

Several years ago the term "aspect oriented programming" was in vogue. Decorators seem to me _the_ way to implement AOP.

you are gods gift for me thank you very much. are not you planning for doing some projects in python.

I've only used a handful of decorators in python, but what I'm curious about is what @abstractmethod brings to the table here, in the first section of the video. I'm familiar with the idea that declaring something abstract (in languages that allow it) prevents you from creating a subclass without providing your own definition of that method. Is that all that's being done here? I admit that not usually being a library programmer, I tend to just document what things need to be done rather than build out a hierarchy to make the compiler enforce it.

Note that if you want decorators to support both sync and async functions, you can switch based on the value of inspect.iscoroutinefunction()

Decorators are a wonderful way to challenge people to explore the more abstract tools in Python and their also wonderful for making DRY-er code. I recently used decorators to support a test structure, where the decorator would display information, e.g. pass/fail the return of all the test, given the test methods only returned bools.

Can you explain pyTest specially parameterize pytest where results can be stored and send to end users in proper format

wow real magic

I wanted to ask a question but writing my question answered it, thanks

Amazingg

hey Arjan. can you share your thoughts on using result tuples such as the one below in python? good idea or bad idea? ``` def result(func): def safecall(*args, **kwargs): try: return (None, func(*args, **kwargs)) except Exception as e: return (e, None) return safecall @result def div(x, y): return x / y X = [1, 1, 1, -1] Y = [2, 0, [], 2] for x, y in zip(X, Y): err, res = div(x, y) if err: print(repr(err)) continue print(res) >>> 0.5 >>> ZeroDivisionError('division by zero') >>> TypeError("unsupported operand type(s) for /: 'int' and 'list'") >>> -0.5 ```

Lovely vidoe as always here is a video idea for you: How to Code inefficiently.

@ArjanCodes

Жыл бұрын

Haha, good suggestion, with some reverse psychology :)

Everyone else is giving proper accolades for the video, so I just came in to say well done for "Pain in the Class" 😂👏

@ArjanCodes

Жыл бұрын

Haha, thank you Chris!

Hello! It's possible to use @decorator for wrapping a class method?

@ArjanCodes

Жыл бұрын

Yes, you can certainly do that. An example where this is used is the @property or @abstractmethod decorators.

I use decorators in fastapi for user's token authorization.

Is it common/good practice to allow exceptions to be raised inside a wrapper function?

Tak!

@ArjanCodes

5 ай бұрын

Thank you for your support, Cassidy!

What is the difference between functools and setting default arguments in function?

@ArjanCodes

Жыл бұрын

The difference is that with functools partial you can create different versions of the same function, but with a different value applied, while there’s only one possible default value. A second, more fundamental difference is that partial creates a new function that doesn’t even have the argument anymore.