__new__ vs __init__ in Python

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mCoding

mCoding

Күн бұрын

What's _new_ and what's the difference vs. __init__?
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What's the difference between the "__new__" and "__init__" magic methods in Python? New is for object creation, and init is for object initialization. It is rare that a programmer would actually need to override new, so let's see some examples of how it can be used.
― mCoding with James Murphy (mcoding.io)
Source code: github.com/mCodingLLC/VideosS...
Python new docs: docs.python.org/3/reference/d...
tp_new in CPython: github.com/python/cpython/blo...
C extension example: cython.readthedocs.io/en/late...
Singleton pattern: en.wikipedia.org/wiki/Singlet...
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CHAPTERS
---------------------------------------------------
0:00 Intro
0:50 New vs init
2:51 Main purpose, subclassing immutable types
5:03 Singleton example
6:35 Client caching example
7:58 Encrypted file example
10:33 Metaclasses

Пікірлер: 267
@Jakub1989YTb
@Jakub1989YTb 2 жыл бұрын
This chanel has a very high python value. It's nothing like the others, recycling docummentation or from one another. You can easilly see this on the file examples, where there are codecs and itertools correctly used.
@mCoding
@mCoding 2 жыл бұрын
I'm happy that my viewers can see and appreciate everything I put into the videos! Thanks for being an awesome viewer!
@amir3515
@amir3515 2 жыл бұрын
Yes I like this channel for quick examples of certain features and learning why things are the way they are and what you can do with those features. For software architecture and design patterns I like Arjan Codes. Especially the innovative code roasts series
@baudneo
@baudneo 2 жыл бұрын
Absolutely, you are quite literally the only person I have clicked the notification bell for. Top notch content, keep it up!
@dsnein
@dsnein 2 жыл бұрын
Yeah, everybody else for this language has one of a few gimmicks running. Selling entry level courses, covering some thing with a crummy library under the clickbait premise that its a smart to thing to learn because it uses “so few lines of code”, or, well, intermediate level courses. Almost no explaining builtins and patterns.
@mumujibirb
@mumujibirb 2 жыл бұрын
Quite useful when I want to know something. Straight, to the point. I still think it’s funny that I went: time to learn python to make a quadratic cracker despite having no experience in non block coding, and after a summer, I am now ok at python!
@NOPerative
@NOPerative 2 жыл бұрын
Decrypted message zoom in was priceless. As usual, excellent video.
@mCoding
@mCoding 2 жыл бұрын
Thank you very much, glad you enjoyed it :)
@mutenpo
@mutenpo 2 жыл бұрын
@@mCoding Love your videos. Finally subscribed, that zoom in was well done.
@rogervanbommel1086
@rogervanbommel1086 2 жыл бұрын
@@mCoding yea, may I ask why you chose those TERRIBLE encryption algorithms
@theninjascientist689
@theninjascientist689 2 жыл бұрын
@@rogervanbommel1086 I'm assuming so that people wouldn't try to use his code for actual encryption and blame him if things went wrong?
@awwastor
@awwastor 2 жыл бұрын
@@rogervanbommel1086 what do you mean? he used the only mathematically proven unbreakable encryption algorithm
@kennethlew
@kennethlew 2 жыл бұрын
I really like how you get straight to the point and give clear and concise explanations. This channel is one of the best if not the the best resource for understanding more difficult concepts in python.
@VY_Canis_Majoris
@VY_Canis_Majoris 2 жыл бұрын
I didn't even know __new__ was a thing until seeing this video. I've always used __init__ and that's what I've seen other people always do as well.
@mCoding
@mCoding 2 жыл бұрын
Completely understandable, you can go your whole life and never actually need to override new, but init obviously is needed all the time.
@robertbrummayer4908
@robertbrummayer4908 2 жыл бұрын
Man your videos are awesome. I like that they are so much on point without artifical fluff to make them unnecessarily longer. Every video has one topic and sticks to it similar to "a function should do one job only" :). Great job!
@azratosh
@azratosh 2 жыл бұрын
Quality content, yet again. Idiomatic Python, concise explanations, nothing less. 11/10
@eldattackkrossa9886
@eldattackkrossa9886 2 жыл бұрын
thanks shrek
@oxey_
@oxey_ 2 жыл бұрын
Another banger, as we've come to expect at this point :) I remember reading the documentation on this but the only thing that stuck was the fact new creates the class and runs before init - what that actually meant or what I could do with it I had no idea, but changed this! Great video
@royler8848
@royler8848 2 жыл бұрын
This channel is the only one on KZbin that actually showcases unique and interesting stuff and doesn't just read out the iter-tools docs.
@mCoding
@mCoding 2 жыл бұрын
Many thanks for the kind words. I love reading itertools docs :)
@plfreeman111
@plfreeman111 2 жыл бұрын
The value of a singleton is when you need an abstraction to something where there is an actual constraint that "there can be only one". The classic example is hardware access. Suppose you open a connection to a device that only supports a single connection (e.g. a COM port), and a set of objects that can access that device. Making the device abstraction a singleton is a great design pattern. Any object can instantiate the device object. If it's the first one, a new object is instantiated. If it's a subsequent construction, the object gets a reference to the already instantiated device.
@micalobia1515
@micalobia1515 2 жыл бұрын
Nice video! That last point really highlighted where I might personally use __new__ in my own projects, really insightful video!
@mCoding
@mCoding 2 жыл бұрын
Great to hear!
@yonataneavri8298
@yonataneavri8298 2 жыл бұрын
Hi, I really like your videos and they always help me understand something i didn't know in python! Thank you!
@mCoding
@mCoding 2 жыл бұрын
Happy to hear that!
@dot_dot_pwn2650
@dot_dot_pwn2650 2 жыл бұрын
Dude you're amazing, I've never seen anyone cover python at the level you do. Amazing detailing and explanations. Also , quick and easy to watch! Great stuff! 👍
@qorbanimaq
@qorbanimaq 2 жыл бұрын
Excellent, just as always! The Python level you teach is just another level. Love your videos. Can you do a tutorial on super function as well? I would really appreciate that.
@QuantumHistorian
@QuantumHistorian 2 жыл бұрын
Yes, that would be good, especially in the case of multiple inheritance. Actually, the do's-and-don't's of multiple inheritance in general would be great
@christiansinger2497
@christiansinger2497 16 күн бұрын
Man I'm just so happy that such high quality content is for free. Greetings from Germany!
@marquinho1p
@marquinho1p 2 жыл бұрын
oh man - the awkward pause to subscribe was GOLD. these vids are great - I didn't know about the __new__ method - I'm intrigued! Sincerely, -new subscriber
@rmannion16
@rmannion16 2 жыл бұрын
Really loving this channel, always finding new ways to do things. Thank you!
@adamcetinkent
@adamcetinkent 2 жыл бұрын
I'm always finding init ways to do things!
@haoli6628
@haoli6628 2 жыл бұрын
I spent hours on internet, this is the only video/blog explain clearly about __new__ and __ini__ !! Especially the part about when we need to modify __new__(). Thank you so much!!
@cemlynwaters5457
@cemlynwaters5457 2 жыл бұрын
This is very useful for helping people learn about what happens when an object is being created. Nice examples of when to specify your own new method! Great material!! 😁
@hupa1a
@hupa1a 2 жыл бұрын
Great one! This is really high quality content! Can't wait for the video on metaclasses
@jostrossel7280
@jostrossel7280 2 жыл бұрын
Great as always. I'm really looking forward to the meta class video, I never really got those.
@srijanmukherjee4658
@srijanmukherjee4658 2 жыл бұрын
I am always learning new stuff here, you are awesome! thank you for these contents. They really help us a lot.
@mCoding
@mCoding 2 жыл бұрын
Happy to hear that!
@tandavme
@tandavme 2 жыл бұрын
Thank you James, great explanation!
@darvil82
@darvil82 2 жыл бұрын
Nice video! The examples are really appreciated.
@mCoding
@mCoding 2 жыл бұрын
Glad it was helpful!
@comedyclub333
@comedyclub333 2 жыл бұрын
Holy shit, although I work everyday with python on an advanced level your videos make me feel like I didn't know anything. I really like your videos since it seems like they are the only resource constantly delivering pro level python tutorials.
@mCoding
@mCoding 2 жыл бұрын
You're welcome! Keep watching and you'll learn all the stuff too!
@comedyclub333
@comedyclub333 2 жыл бұрын
@@mCoding One question: Why did you call object.new in your last example instead of super().new like the examples before. Does this make any difference? As far as I undestand it would make a difference if your Base class iwould inherit something from another class, right?
@TheRiskyChance
@TheRiskyChance 2 жыл бұрын
I'd like to recommend the channel AnthonyWritesCode. The guy behind it maintains Tox, Flake8, and DeadSnakes.
@georgplaz
@georgplaz 2 жыл бұрын
I love those videos where you look at one single issue and explain it in-depth! while all of those videos may already exist on yt, most are just not as well made. yours are a joy to watch!
@mCoding
@mCoding 2 жыл бұрын
So glad to hear your kind words! Thanks!
@prakhargarhwal4304
@prakhargarhwal4304 2 жыл бұрын
Brilliant video. You are one of the very few programming channels which are presenting stuff which helps you move from a beginner software developer, to an intermediate one.
@AngryArmadillo
@AngryArmadillo 2 жыл бұрын
After many years of daily use, I thought I new everything about python. Your videos never fail to prove otherwise. Thanks for the excellent content!
@harripj_
@harripj_ 2 жыл бұрын
Excellent video! I have never used __new__ myself, but would consider it now- very well explained, thanks!
@QuantumHistorian
@QuantumHistorian 2 жыл бұрын
The last example seems like it would be done more simply with a factory pattern too
@mCoding
@mCoding 2 жыл бұрын
The comment I made about Factory pattern was meant to apply to all the creational patterns in this video! The main intent of overriding new is subclassing builtin (or C extension) immutable types.
@romanshevtsiv3526
@romanshevtsiv3526 2 жыл бұрын
Insanely great! Thanks for your work!
@marzband
@marzband 2 жыл бұрын
I learned something new! (__init_subclass__) Thanks! This is a great channel!
@RAZREXE
@RAZREXE 2 жыл бұрын
So good, glad I found your channel
@wayneqwele8847
@wayneqwele8847 2 жыл бұрын
I always learn something intimidatingly new here thanks for the video.
@joewyndham9393
@joewyndham9393 2 жыл бұрын
Had I not seen this last year, today I would have fumbled around with __init__, not understanding what I was doing, and it would have cost me hours. Cheers for another top shelf lesson in the finer points of Python
@samuelkyei1162
@samuelkyei1162 2 жыл бұрын
You always makes me feel like I know nothing in python😄😄. I really like this channel.
@ashishjain518
@ashishjain518 2 жыл бұрын
Exactly!! While watching @mcoding videos, I feel like I need atleast 2 years of experience in Python, but when I look at the general knowledge about the understanding of Python in companies and market, there is a big difference 😂
@samuelkyei1162
@samuelkyei1162 2 жыл бұрын
@@ashishjain518 😄😄
@JotaOcaranza
@JotaOcaranza 2 жыл бұрын
Ive never learn so much with just one python video You are awesomeeeee, the múltiple examples reaaaally make things way easier to understand and the performace tips are very intresting and usefull
@carlossegura403
@carlossegura403 2 жыл бұрын
I needed this, thank you!
@abhishektiwari9561
@abhishektiwari9561 2 жыл бұрын
After this video.. I still have lot of things to learn in Python. This is such a quality video. Thank you.
@QuantumHistorian
@QuantumHistorian 2 жыл бұрын
In the Singleton example, do you not have the problem that __init__() will be called multiple times? If __init__() does anything non-trivial, this could be a huge problem. Or does overriding __new__() mean that __init__() might not get called? But that's not what it looks like at 1:20
@mCoding
@mCoding 2 жыл бұрын
The code at 1:20 gets called every time someone does Singleton(), so indeed every time you call this, the init will be called, and hence if new is returning a single instance the init will be called on the same object as many times as Singleton() is written. Therefore, if you use the singleton pattern this way, your init should either be empty or at least not modify the object. Most builtin types either have any empty new or an empty init.
@shashanksharma7242
@shashanksharma7242 2 жыл бұрын
Subscribing right after the zoom in :P
@amoghskulkarni
@amoghskulkarni 2 жыл бұрын
This might be the only programming channel that I'm seriously considering binging the content of
@punktdotcom
@punktdotcom 2 жыл бұрын
I always wondered why the heck we use 'self' in the __init__ method. Now I know! Thanks for this informative video, it helped alot!
@tpahere8756
@tpahere8756 2 жыл бұрын
Again a very high quality video! Thanks a lot
@shempincognito4401
@shempincognito4401 2 жыл бұрын
I tend to never subscribe to a channel as a response to being asked... But this was both sneaky and fun so now there's an exception to that rule. Also thanks for the clear and concise videos!
@AkashGupta-th2nm
@AkashGupta-th2nm 2 жыл бұрын
Today I learnt about ```__new__```. But I also learnt about ```print(f'{EXPRESSION=}')``` That '=' at the end is rly neat
@DanielLavedoniodeLima_DLL
@DanielLavedoniodeLima_DLL 2 жыл бұрын
He covered that in another video. He has great content!
@kblueleaf
@kblueleaf 2 жыл бұрын
This channel is so good for me who bury them self into python a lot of details about how python work and pythonic technique Love!
@BdT141
@BdT141 10 ай бұрын
Great content as always. Going to use the EncryptedFile example instead of a proxy class in my code.
@michadarowny3811
@michadarowny3811 2 жыл бұрын
Finally someone explained this, so many people call __init__ a constructor.
@NoNameAtAll2
@NoNameAtAll2 2 жыл бұрын
init is constructor of the object new is constructor of the bases :/
@michadarowny3811
@michadarowny3811 2 жыл бұрын
@@NoNameAtAll2 I would disagree , considering definition of the class constructor.
@dabusdruva
@dabusdruva 11 ай бұрын
Caching clients is a super practical example. I've used this technique numoirous times in production code.
@raghavgupta6186
@raghavgupta6186 2 жыл бұрын
Nice content 👍 , Thanks for sharing 🙏
@arshia.sasson
@arshia.sasson Жыл бұрын
9:20 This is actually perfect for a mini-feature I wanted to implement previously (generating a complete list of classes that all derive from the same base class). I still have to manually import all these classes, but at least I can now dynamically generate the list based on imports (I presume) instead of manually editing a list.
@tobyjacobs1310
@tobyjacobs1310 2 жыл бұрын
I've been trying to find a good definition of what subclassing entails in python for the last couple of months. I now understand the distinction vs e.g. subclassing a window's render hooks in COM. Thanks!
@damiananslik6214
@damiananslik6214 2 жыл бұрын
Amazing content. Learning so much 😌
@Dtomper
@Dtomper 2 жыл бұрын
You're one of the most if not the most underrated programming channel on KZbin.
@pranavnyavanandi9710
@pranavnyavanandi9710 2 жыл бұрын
These videos are all those questions you Google and find answers to on stack overflow.
@langnostic5157
@langnostic5157 2 жыл бұрын
Saving this for later. I think I can use that init subclass pattern at work
@mCoding
@mCoding 2 жыл бұрын
It's useful because init subclass will be inherited across multiple levels so you don't need to recursively track children, they just automatically call init subclass anyway!
@pier-oliviermarquis3006
@pier-oliviermarquis3006 2 жыл бұрын
Please make more videos about design patterns and the context in which they are best used.
@scorix_
@scorix_ 5 ай бұрын
I loved the look at the end saying "take the hint" xD
@vinay1744
@vinay1744 2 жыл бұрын
Mind = Blown. Amazing stuff
@anibaldk
@anibaldk Жыл бұрын
Hands down, best Python channel out there.
@cirogarcia8958
@cirogarcia8958 2 ай бұрын
Really cool! The singleton pattern was the first thing that came to mind for me when I learned about the __new__() method. However, there is a small problem that other languages don't have. When you return the an instance in __new__(), __init__() will ALWAYS be called (if the type returned is correct). This means that in the singleton pattern, whenever you use the constructor to get the existing instance, it will be reinitialized, unless you explicitly add a check at the start of your implementation so it is only initialized once. Here is an example of a complete implementation of the singleton pattern circumventing that issue: ``` class Singleton: __instance = None __initialized = False def __new__(cls): if cls.__instance is None: cls.__instance = super(Test, cls).__new__(cls) return cls.__instance def __init__(self): # Check if the class has been initialized if self.__initialized: return # Mark the class as initialized, so that the initialization code # doesn't run more than once when the class is instantiated again self.__initialized = True # Actual initialization code self.attr = 1 ```
@mCoding
@mCoding 2 ай бұрын
You could also override the dunder call on the metaclass so avoid this issues.
@Pedritox0953
@Pedritox0953 2 жыл бұрын
Excellent video!
@valtsmazurs4056
@valtsmazurs4056 2 жыл бұрын
Nice video with good and concise explanations! I'd only add some thread safety to the singleton example, the current example would potentially lead to race conditions if used in production code.
@mCoding
@mCoding 2 жыл бұрын
Thanks! The normal singleton design pattern is not thread-safe, but indeed if your singleton is mutable and you access it from multiple threads then you would need to add some kind of synchronization.
@0x0jx
@0x0jx 2 жыл бұрын
Thx very much!
@tayyabhasan
@tayyabhasan 2 жыл бұрын
i need a complete course from this channel.
@DanielLavedoniodeLima_DLL
@DanielLavedoniodeLima_DLL 2 жыл бұрын
Another great video, James! You're the only one in KZbin that I found that covers advanced Python topics in a simple and clear manner! Could I request a topic for a video? I never quite understood how can I bundle C code in a Python package like Numpy does, for example. Could you cover that topic in a future video? Thank you for sharing your knowledge!
@mCoding
@mCoding 2 жыл бұрын
Thanks! C extensions are on my list don't worry!
@jamessimmons9998
@jamessimmons9998 2 жыл бұрын
I just want to let you know that this channel is basically single-highhandedly teaching me all of the 'advanced' python techniques/knowledge I know. Obviously I do my own research as well, but there are a lot of things that you just can't look up if you don't know they exist.
@mCoding
@mCoding 2 жыл бұрын
Great to hear :) glad you enjoyed my videos!
@topperthehorse
@topperthehorse 2 жыл бұрын
I've been using Python for a decade and I never ___new___ this!
@rexygama7697
@rexygama7697 2 жыл бұрын
Cool video!
@dedpossum66
@dedpossum66 2 жыл бұрын
Great stuff
@user-hk3ej4hk7m
@user-hk3ej4hk7m 2 жыл бұрын
Thumbs up for how clearly you explain these things, however I do feel as there could have been more examples on subclassing immutable data types and restricting their domain. Say if you want to make a class for natural numbers that inherits from int, or a string that's strictly an email address. Doing validation at the type level encourages the "parse, don't validate" design pattern, that I personally think we could use more of.
@janawillms3347
@janawillms3347 2 жыл бұрын
u a monster man, love your videos
@mCoding
@mCoding 2 жыл бұрын
Thanks for the love, I appreciate it!
@Sarsanoa
@Sarsanoa 2 жыл бұрын
an annoying issue with the singleton/caching use case is it will call __init__ on your pre-existing object every time, essentially making __init__ unusable, which can be a rather unfortunate gotcha. In these cases it's almost always more clear to use a function/classmethod instead, and maybe use a different language feature to prevent __init__ from being called nakedly.
@lawrencedoliveiro9104
@lawrencedoliveiro9104 Жыл бұрын
But if you don’t put anything in your init method, then it will do nothing. Put all the object setup in the new method instead.
@ttrindademendes
@ttrindademendes 2 жыл бұрын
channel is underrated!
@senyai
@senyai 2 жыл бұрын
I create classes with static and class methods, then create dunder new to make the class behave like a function. My colleagues don't like it, but I find it quite useful for splitting large functions.
@comedyclub333
@comedyclub333 2 жыл бұрын
How do you mean this? What are the class methods for if your dunder new just acts like a normal function?
@senyai
@senyai 2 жыл бұрын
@@comedyclub333 For example: `def _ _ new _ _(cls, a, b): return cls._f2(cls._f1(a), b)`
@comedyclub333
@comedyclub333 2 жыл бұрын
@@senyai Oh okay so you are basically splitting you function up and encapsulate everything inside this modified class to only expose the first function?
@TheRiskyChance
@TheRiskyChance 2 жыл бұрын
> My colleagues don't like it I wonder why 🤔
@Jakub1989YTb
@Jakub1989YTb 2 жыл бұрын
The uppercase tuple is great candidate for a coding challenge. I'll use it on my colleagues.
@mCoding
@mCoding 2 жыл бұрын
Roast them then make sure to share the vid with them afterwards :)
@calvinli9975
@calvinli9975 6 ай бұрын
Thanks for the content!! Do we consider the Encryption sample as strategy pattern? And I think my question is that, what is the benefit implementing in this way comparing with passing different encryption method into a third class?
@ssholum
@ssholum 2 жыл бұрын
The main topic of this video was definitely interesting, but at 6:30, I learned that you can make an f string print the expression as well as the evaluation by adding an = inside the curly braces. Now I'll need to actually read the documentation on f strings to see if there are any other special bits like that. I just thought it looked at the content of braces, evaluated them, concatenated the string, and then printed it, but apparently it does a lot more than that, since {x is y =} should give a syntax error. EDIT: and now I see that you have a video on that very topic. Watching now.
@mCoding
@mCoding 2 жыл бұрын
I have a feeling you will enjoy a lot of my videos :)
@MrFluteboy1980
@MrFluteboy1980 Жыл бұрын
The EncryptedFile example reminded me of an Abstract class implementation. I'm not sure if python supports abstract classes the way other languages do, but this reminded me of it.
@user-xh9pu2wj6b
@user-xh9pu2wj6b Жыл бұрын
python supports abstract classes in a kinda unusual way. You need to use an abc module and do something like this: from abc import ABC, abstractmethod class Abstract(ABC): @abstractmethod def someMethod(): pass This essentially makes it so you can't create an instance of an abstract class and any class inheriting from it has to define all methods marked as abstract or else it'll cause a TypeError when you try to create an instance of a derived class.
@yashdawani1909
@yashdawani1909 Жыл бұрын
Quite Fascinating, how adding a = to a print statement would calculate the value as well.
@iuliandumitrache7307
@iuliandumitrache7307 2 жыл бұрын
Can you do more content about design patterns in Python?
@iamzeus1250
@iamzeus1250 2 жыл бұрын
Thanks
@maheshcharyindrakanti8544
@maheshcharyindrakanti8544 Жыл бұрын
took me a while due to mistake, but it works thanks
@oysteinsoreide4323
@oysteinsoreide4323 Жыл бұрын
if you implement some sort of plugin pattern with factory class instances. Using the singelton pattern to solve that is a very good solution. There are also probably more situations where singletons are viable as a solution. Especially if the concrete class that is going to be made is not know for the code that needs to make new instances of an object.
@falxie_
@falxie_ 2 жыл бұрын
I didn't even know __new__ existed, seems really niche, but potentially useful
@Bauibaubau
@Bauibaubau 2 жыл бұрын
Great video! But I did not understand the drawback of a singleton? Isn't your client example a Singleton too?
@CatMeowMeow
@CatMeowMeow 2 жыл бұрын
As someone who isn't really familiar with factory pattern, it'd be cool to see how that last example would be better implemented using factory pattern instead
@wojciechszweda5140
@wojciechszweda5140 2 жыл бұрын
Great video, bump for algorithm
@mCoding
@mCoding 2 жыл бұрын
Much appreciated!
@pranavnyavanandi9710
@pranavnyavanandi9710 2 жыл бұрын
Hello. You mentioned the terms "Factory pattern", what does it mean? You said it was a better suited option to solve the client example you took. Also, at 9:20, you refer to the dunder method __init_subclass__ as a "hook", could you explain what a hook means? If it is a generic programming term, I'd appreciate if you linked a website or resource explaining it in simple terms. Thanks.
@JethroYSCao
@JethroYSCao 2 жыл бұрын
Thanks for showing me the existence of ___init_subclass___
@mCoding
@mCoding 2 жыл бұрын
Very welcome!
@technowey
@technowey 2 жыл бұрын
Thank you for another great video. The comment mentioning that a singleton has the same issue as a global variable misses the point of a singleton. A singleton is only used when, by design, only one instance is desired. Usually this is a poor design choice, but not always. There are some cases where only one item of a given type should exist. I agree about using the Factory patter. The book, "Design Patterns" changed the way I design code. I knew some of the contexts. That book provided a way to think and communicate design ideas.
@dakalamin
@dakalamin 2 жыл бұрын
Who were the authors of the book?
@Obbe79
@Obbe79 Жыл бұрын
The presence of "self" in the init signature should give away the fact that the instance already exists when the init is called
@bluejimmy168
@bluejimmy168 2 жыл бұрын
at 9:30, what does prefix="rot13" do? Are you extending from two classes EncryptedFiles and prefix? Not sure what prefix is. Thanks.
@mCoding
@mCoding 2 жыл бұрын
These are called metaclass keyword arguments. www.python.org/dev/peps/pep-3115/#specification It passes the keyword arguments to many functions that the metaclass calls when instantiating the class.
@MithicSpirit
@MithicSpirit 2 жыл бұрын
Discord gang
@abraarz2971
@abraarz2971 2 жыл бұрын
🤚
@mCoding
@mCoding 2 жыл бұрын
👋
@dabusdruva
@dabusdruva 11 ай бұрын
Singletons are also super hard to test because of tight coupling and difficulty to mock in tests.
@Mr1995Musicman
@Mr1995Musicman 2 жыл бұрын
I have rediscovered new several times, each in the context of caching objects that are singletons, as in it only ever makes sense to have one instance with a given input. Note: these were all little math puzzles or personal projects, I wouldn't ever touch new in any serious context without a lot of thought and if there was really no other solution. It's not trivial to test, and it definitely goes against common practice.
@dhaves
@dhaves 2 жыл бұрын
Glad i've already had a subcription...
@dorb1337
@dorb1337 2 жыл бұрын
Just WOW. I didn't know a thing before, and now I know that I didn't know, unfortunately I still don't know.
@alexandert8235
@alexandert8235 2 жыл бұрын
is there a formal design pattern name for the pattern used in the "Encrypted File Example"? Is that an implicit "factory"?
@alexandert8235
@alexandert8235 2 жыл бұрын
ah, nvm, just saw your reply to an earlier comment about factory patterns in this vid. thanks!
@mdarian
@mdarian 2 жыл бұрын
Hi James, You mentioned (5:20) that the singleton is a way to do a global configuration object. You said personally that you can't recommend it. Do you have a better way in any of your videos? Thanks
@mCoding
@mCoding 2 жыл бұрын
Hi Darian! Global configuration is one of those things that I've yet to find "the one true answer" for, unfortunately. Due to the nature of it being global it often times does make sense to have it as some kind of global object, though the singleton pattern specifically is particularly confusing for many developers and it also makes testing difficult. I would say that just having a single global instance is often times a decent solution. Note that a single global instance is different from a singleton because you could theoretically make another instance of the global config, you just choose not to, whereas with a singleton you would have to do some class surgery to make another instance (typically necessary during testing code).
@mdarian
@mdarian 2 жыл бұрын
@@mCoding Thanks James. I've been using a class and loading up all the class variables for a global config for things like credentials and app options. Then using an instance of the class to encrypt/decrypt passwords etc.. but the singleton sounds like it will do the same job. From my googling, everyone seems to agree that there is no good solution either. Maybe a topic for a video?
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