The Only Time You Should Use Polymorphism
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- čas přidán 26. 06. 2024
- The only time you should use subtype polymorphism is when you have behavioural variation in the subtypes. I teach two university courses on object oriented programming and I see this problem a lot. Let me explain. RECOMMENDED READING:
🛠️ geni.us/k8KhT3 (Refactoring)
⭐️ geni.us/zzlx (Dependency Injection: Principles, Practices, and Patterns)
💎 geni.us/hNDE (Elegant Objects)
🏛️ geni.us/IBhtLnh (Clean Architecture)
🧩 geni.us/nlbA6 (Head First: Design Patterns)
Read my FREE book on Object Oriented Programming:
🚀 theobjectorientedway.com
Watch next:
• Always Use Interfaces
CONTENTS:
00:00 Thesis
01:16 Example 1
03:28 Example 2
06:25 Example 3
13:26 Summary
Finally he remembered his password
🤣🤣
called it!! 😂
Where you were?, will you make video contunue now@@ChristopherOkhravi
This must have been some variation in data.
He randomly came back after three years! Tak! Good to see you again.
Yessssss I'm glad he is back man, I've learned so many things important on my career because of his videos
Love him, jest super
OMG I can't believe this, I asked him last week on Twitter when he is coming back..and here he is. 🐐
What are the chances he’ll stay with us for some time now 😅
@@DerRabeKirilldepends if project manager leaves him alone
I like to think, that you got so annoyed by someone at work using subtype polymorphism the wrong way, that it brought you back here ;)
I teach at a university so I read a lot of student code 😉
in which university do you teach I need to attend there, you're a CS legend
@@ChristopherOkhravi
I wish more people in your team do things in wrong way that you make more videos to teach others 😂
Man, your notification popping up is the best thing happened in months❤, please don't disappear again :)
literally just watched your design patten playlist, thinking why hasn't he posted for 3 years. perfect timing
Welcome back! Got a huge amount of value out of this channel in my early days of becoming a dev
Have been watching your Design Patterns series and the code walks videos and was always thinking if I ever wanted to have a youtube channel it would have been of this style. If only he was back. Wish granted, welcome back, so happy to see notifications from you! :DDDD
I came to the comments section to share my excitement about your return.
But, wow, I didn't expect there to be so many of us!
I've never been more engaged with software engineering CZcams content. Your presentation skills are excellent.
I didnt even fully read the title, I just saw the thumbnail and clicked. Welcome back good sir.
I would add a point that "variations in behavior" can also come from _outside_ the class - a class can just be a data type, without being responsible for all the ways the data will be used. Imagine an Attack subtype, EnergyAttack, which has an additional property EnergyType. Now Scratch is a base Attack instance, and Thunderbolt is an EnergyAttack (with EnergyType = Lightning). Looking at just the class definitions, you could say this is a data-only variation, but it makes sense because the change is in the data structure (an additional property), not just values. These subclasses may or may not implement variations in behavior themselves, but _allow for_ external variations by being different types: We may have many general functions that work with the Attack type, as well as some functions that accept EnergyAttack specifically and work with the EnergyType property.
Suddenly you appeared out of thin air, please be consistent. Love your content.
No one told you to wait
we aint entitled to his time
He can post whenever he feels like posting. How entitled are you. Anyway thanks for the content ignore comment like above
Oh my god. I used to watch your videos when I started learning programming in 2021. Right now, I have an interview with Google scheduled next week. You don't know how happy I am to see you back. Thanks for coming and welcome back :)
Glad to hear 😊 Best of luck on your interview!
The man, the legend, welcome back
please continue have been rewatching your old stuff so glad to see this
I started watching him on thursday, fell in love in his way of teaching, and was thrilled when saw that last video was posted 3 years ago. And now he appears out of nowhere 😂 If you were giving lectures on my Uni, i wouldnt miss a single one
Awesome to see you back Chris! I’ve learned a lot from your videos, and have always enjoyed hearing your perspective on things. 😎👍
Your teaching is the greatest and simpler....❤
I've been watching your playlists whilst working on my project over the last year, and this video is so relevant to what I'm currently working on, and exactly what I've been asking myself while working on my current systems. Being self taught I don't know the theory very well, so I would had never known that I was dealing with 'sub-type polymorphism'. Good to know I've been going down the right path, and also to know what it's called!
Great to see you again Christopher. Miss your videos of design patterns and discussions about principles. Welcome Back!!
Best notification from CZcams in ages. I hope you've got more for us. 100% my favourite videos covering software development!
Welcome baaaaack!!!!!!!!! Happy to see you around after so much time! Hope you'll stay for a while, your content and way of explaining things are precious.
Last month i was discussing with my friend about Design patterns and in that discussion i recommended him your channel. While discussing i said to him that don't know why you aren't posting any content. I was little bit worried about you. Now i am very glad to see you back. 🥳🥳🎉🎉❤❤❤
Love to see you again, I look forward to rewatching as much of your videos as possible !
WHOA! i started watching your pattern videos like a week ago, binging them while at the gym, while taking walks, etc. i was like "eh it's been a long time since hes posted...he was a good teacher" and then here you are!!
So happy to see you back. You're the sole educator whose CZcams videos I choose to view at regular speed, even when they extend to an hour.
Happy to see you upload after 3 years love the way you teach..
I watch your videos and you are the first teacher whoes course i can buy without thinking about money.
Glad CZcams was smart enough to recommend your video. Glad to see you posting. Always top notch stuff.
Glad that see you again, hope I can see another series also before I die. But high quality takes times, I'm really enjoying when watching your videos.
Glad to see you're back uploading videos! Your series on design patterns were instrumental in taking another step in my career!
From last week I started watching your Design Pattern playlist and thinking why Chris stopped posting videos for last 3 years. To my surprise there was a notification😮. Your teaching is so great and natural, not everyone gets so easily. Keep up the Great work!
I've really missed these talks. Welcome back!
happy to see you are back! keep the content coming! learning a lot.|
love the whiteboard, the editing and the why you teach :)
I did not expect you coming back, loved your design patterns, glad to see you're doing well!
Hey @Chris, it's great to see you after such a long time! I've always been a fan of the way you present content with crisp editing.
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Your channel helped me get into functional programming, and now i'm absolutely obsessed. Do you have any plans for more FP related videos?
Man, I was so happy to see your face in my feed again. Glad to have you back, your videos always helped me understand these concepts so much better.
Finally you are back!
I enjoyed so much your design patterns playlist.
I don't have words to describe how happy I am to see you back.. Love your style of teaching
I missed your videos, thanks for coming back!
I didn't learn anything, but the way you described the information in the video *clarified* what I'd already known -if that makes sense.
You are excellent at explaining things in very clear terms, and I appreciate that. Subbed.
I'm very happy to hear that. Also, thank you for the sub. Welcome 😊
We've been waiting for you to come back! - so WELCOME BACK ^^!
I like this format. My ADD was trying its best to block the info, but this guy just kept going :)
Legend is backkk!!! Good to see you, your system design videos are epic!! MASSIVE THANKS
Once again, you enlightened me about something that might seen implicitly known and simple but in reality a truly good software engineer needs to be absolute aware of.
Welcome back Chris. Have learnt a lot from your design pattern series!
We miss your valuable teach.
Welcome back Christopher. Good to see you back 😊 Keep up the good work and make learning fun and easy. All power and good wishes ❤
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The king of Design patterns is back🔥
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Your Design pattern playlist is the best I have ever seen on any channel/courses. It was about a year ago I started and completed the DP videos, but was disappointed to see no more , and randomly today this video pops up on my feed, very happy to see you again hopefully you will complete the rest of the patterns too 😊. I tried connecting you on LinkedIn too but it was restricted I think 😅.
This is the first video I watch from you. It makes complete sense, no idea why I never though of it like this. Looking forward to more videos!!
I'm very happy to hear. Welcome 😊
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Word to mother....ur design patterns videos helped me nail an interview in 2017 🤣🤣🤣. Now I'm a Lead software engineer. Thanks
Thanks for coming back man
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Welcome Back, Great to see you after 3 years :D
it's been a very long time, nice to see again man!!
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Good to see you after 3 years. I love the way you teach.
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Welcome back! Please upload more videos on system design and LLD. We appreciate your effort!
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Welcome back ! , good decision to come back , your content is wonderful
I did not expect to see this in 2024, but I'm glad to see you're back. 😁
This is one of the most engaging software videos I've ever seen
Good to have you back!
I am determined to watch this video as many times as it takes to understand what he is talking about. 10 times later, maybe I should watch a refresher on polymorphism.
Welcome back, sir. Happy to know you are still creating content.
Loved this video. Thank you so much for the bite-size CS training. Love your style, heart, and expertise.
I'm extremely happy you are back. Thank you.
Happy to see you back Christopher :)
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Damn you're back! Thank you very much for the content!
Good stuff. There are solutions without subtypes though.
1. The example as stated could have `Move` that accepts a `name` as well as the individual effects.
`new Move(name, healthEffect, armorEffect)`
So attack would be `new Move('attack', -50, 0)`
I'd only start packing in parameters in a language with named parameters though.
2. You could have a method to add effects to a move as a fluent interface
`addEffect(property, amount)`
`new Move('heal').addEffect('health', 50).addEffect('armor`, 50).
`Use` would just apply those effects to the target. Of course you'd need to do something about validating target properties.
3. Still polymorphic, but passing a `use` function to the constructor of a `Move` class
`new Move('attack', attackFunction) keeps your class hierarchy flat and allows you to define any behavior you want in the passed function. Do we really need an interface and subclasses? Maybe. Maybe not.
Different behavior is just the first condition. For the subtype with polymorphism solution, that behavior has to be complex enough that it's simpler to extend. Class hierarchies add overhead / cognitive load. You need to be gaining enough from the strategy to offset that. This depends on a lot of things. The behaviors, how broad the set needs to be, how its expected to grow, even the language you're writing.
Yeah, like, I think I'd just declare a simple struct with the effect data and pass it in, and expand it as things go (including "no effect" defaults so things don't break). If it does grow enough that this gets cumbersome, by then I'd have a better picture of what actually matters.
Probably would still avoid subclasses tho : p
Previously, thank you for the knowledge, and welcome back.
What I get from the explanation is:
We should/must prefer to be implicit about a specific type of data that has the same structure and behavior, instead of being explicit (where we define it based on the actual concept or domain) about that type (CMIW).
Good to see you again! Welcome back!
Finally! Didn't expect that. 3 years of silence
A video after 3 years. Waiting for many more
omg great to see u again! Ur videos has helped me tremendously during my time at chalmers, and im actually now TEACHING the same course i used ur videos to pass years before! Will recommend ur channel to all my students!
Thank you 🙏😊 And congratulations
Welcome back! Thank you for this! The cliffhanger in the end...oh man, please don't let us hanging for too long
Gotta leave some loops open 😊😊
Glad that you come back
Finally you are back I missed your lectures, thank you sooooooooooooo much ...
Kul att se att du är tillbaka igen! Dina förklaringar av designmönster hjälpte mig enormt under skoltiden. 👍
Man önskade att fler lärare var såhär pedagogiska.
Tack så mycket!
Good to have you back Chris ❤❤
So nice to see you came back,thanks