The Only Time You Should Use Polymorphism 

He randomly came back after three years! Tak! Good to see you again.

Finally he remembered his password

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 ;)

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

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

Welcome back! Got a huge amount of value out of this channel in my early days of becoming a dev

I've never been more engaged with software engineering RU-vid content. Your presentation skills are excellent.

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 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!

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 :)

Awesome to see you back Chris! I’ve learned a lot from your videos, and have always enjoyed hearing your perspective on things. 😎👍

Great to see you again Christopher. Miss your videos of design patterns and discussions about principles. Welcome Back!!

Best notification from RU-vid 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. 🥳🥳🎉🎉❤❤❤

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

I didnt even fully read the title, I just saw the thumbnail and clicked. Welcome back good sir.

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!!

Suddenly you appeared out of thin air, please be consistent. Love your content.

happy to see you are back! keep the content coming! learning a lot.| love the whiteboard, the editing and the why you teach :)

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!

So happy to see you back. You're the sole educator whose RU-vid videos I choose to view at regular speed, even when they extend to an hour.

Glad to see you're back uploading videos! Your series on design patterns were instrumental in taking another step in my career!

I watch your videos and you are the first teacher whoes course i can buy without thinking about money.

Your teaching is the greatest and simpler....❤

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.

Happy to see you upload after 3 years love the way you teach..

I did not expect you coming back, loved your design patterns, glad to see you're doing well!

I've really missed these talks. Welcome back!

Glad RU-vid was smart enough to recommend your video. Glad to see you posting. Always top notch stuff.

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.

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.

I like this format. My ADD was trying its best to block the info, but this guy just kept going :)

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.

Welcome back Christopher. Good to see you back 😊 Keep up the good work and make learning fun and easy. All power and good wishes ❤

I don't have words to describe how happy I am to see you back.. Love your style of teaching

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 😅.

Welcome back, I have missed your content, it is great. Your analysis has been vital to my programming evolution, if only I'd have had teachers with your energy.

Thanks for your work, I got a masters in software engineering 2 years ago and your videos on the design patterns really helped me.

Legend is backkk!!! Good to see you, your system design videos are epic!! MASSIVE THANKS

The man, the legend, welcome back

you did really well with this video, i was able to flip into it and out of it, while just listening and you never lost me. i now know what you put into this video and thats always nice!

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.

Welcome back! Your videos helped me a ton while getting my degree - good to see you're still at it!

Whoa, seeing you in my sub box is not something i expected today. Long time viewer of the channel, since the ramda days! Good to see you back. Your channel helped me get into functional programming, and now i'm absolutely obsessed. Do you have any plans for more FP related videos?

Finally you are back! I enjoyed so much your design patterns playlist.

I missed your videos, thanks for coming back!

Welcome back Chris. Have learnt a lot from your design pattern series!

Love to see you back, hope all good at your end. You have unique way of communicating complex things, Keep making video.

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!

I missed your tutorials man, good to have you back!

Welcome back! So excited to see you back! huge fan of your videos. Thank you!

Oh hey look who's back! Thanks for the video! Ur gof patterns videos helped me a ton a few years back

Welcome back! Please upload more videos on system design and LLD. We appreciate your effort!

it's been a very long time, nice to see again man!!

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).

Thanks for all of these and welcome back!

Welcome Back, Great to see you after 3 years :D

I didn't realise you hadn't posted for three years! I've been taking a break from coding but had to watch this video! Please keep posting!

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.

Wow man, so glad to see u again, you are an amazing teacher, please keep the quality content😊

Loved this video. Thank you so much for the bite-size CS training. Love your style, heart, and expertise.

Thanks for sharing your valuable knowledge again. Your videos about design patterns helped me a lot when I landed my first job as a software developer. I hope 🤞 you don’t give a break anymore 😊

Your knowledge is actually so precious. I love the fact that you just use concepts with whiteboard. Thank You for coming back to us, You can make a lot of us promote with your videos!

We've been waiting for you to come back! - so WELCOME BACK ^^!

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!!

Holy shit. You're back. And the beard is ever so magnificent. Don't you dare disappear for such a long time again.

Welcome back! Good to see you!

Thanks for coming back man

It's so good to have you back. Thank you 😊

Welcome back ! , good decision to come back , your content is wonderful

Word to mother....ur design patterns videos helped me nail an interview in 2017 🤣🤣🤣. Now I'm a Lead software engineer. Thanks

No way!!! You are back! Glad to see!

He's alive!!! Glad to have you back!

Good to see you after 3 years. I love the way you teach.

Thank you bro for coming back

Your teaching is simpler and also in depth, good to see you back on youtube. Please create more good quality content !!

Welcome back! Good to watch your video again!

Glad to see you again, really like your teaching style

Happy to see you back, Chris!

Welcome back, sir. Happy to know you are still creating content.

Damn you're back! Thank you very much for the content!

Love your videos! Great to see them again!

I'm extremely happy you are back. Thank you.

Welcome back and thanks for awesome videos ❤

So nice to see you came back,thanks

Awesome points on polymorphism. Never thought that. Thanks. Really helpful.

Good to see you back!

Great video thank you, and welcome back sensei

Nice to see you back! ❤

Good to have you back!

Good to see you back in the game!

This is one of the most engaging software videos I've ever seen

Good to see you again! Welcome back!

Great to see you again! Love your content, the way you explain complicated things is simple and approachable, love the mustaches also 🙂

I'm really happy that you're back ❤️♥️

I was waiting for this quality content again, thank you so much !!!!