Singleton Pattern - Design Patterns (ep 6) 

Boss: My wife is cheating on me Programmer: One man's constant is another man's variable....

One of the best series I have ever watched. Keep going on dude!

Me: Let me learn about Singleton pattern. Christopher: never use singleton pattern. Me: -_-

Your editing is absolutely fantastic. The stream of knowledge never stops or slows down.

U, my good Sir are born for teaching, really nice and simple explanation for everyone to understand. Keep up the good job! cheers

This is why I love the internet, good videos with good info. My man!

This series is greatest I've ever encountered on youtube on any topic, period.

If there is anything comparable to your teaching skills, it's your skills to have amazing intros. Intro for this particular video is simply genius. Your intros are so underrated man!

The way you teach these lessons is perfect. This is a good example for my lecturers how to teach these stuff.

That's a good video. Especially the code smell part. I would add though that to ensure single instance you also need to wrap instance creation with lock (Monitor), because nowadays threads are used left and right. In fact, "double-checked locking" (that's a pattern) should be used if (instance == null) { lock (_lockObject) { if (instance == null) { instance = new Singleton(); } } }

Everything makes sense with that kind of explanation! Thanks, Chris!

You are criminally underrated. Deserves more followers. Top notch.

“One man’s constant is another man’s variable”... Woow!!

Love these videos, thanks Christopher! The Head First series is great.

The Clean Code links are all great! Now, back to your videos! I wound up learning as much from this as any of your others in this playlist, thanks to the excellent links provided in the description. Singletons seem very convenient, until test-time...

I love the way you teach. Your explanations are thorough and the way you speak is very captivating. Straight to the point, you are not a time waster.

That's what I call 'in-depth explanation'! Awesome work.

Singleton design pattern is simple, however, complicated! every line of the code was explained thoroughly and beautifully.. well done! One of the best videos ever for Singleton!

Thank you for this video and all the rest. I really hope to find every single Design pattern explained by you in this play list.

Already learned this in university and now planning to review again, my professor who teaches that course is very good, and your lecture is as good as the course I learned before ! Thank you so much ! Waiting for more

You are one of the best teachers on the planet. Thanks for the videos.

Your explanation is clear and precise. I enjoyed the video and was able to understand the nuances of this pattern very well.

The way you teach is fantastic, you are my inspiration.

this guy and explanation is pure gem

It was really helpful that you went through the code in this video; great series! :)

First time seeing your videos... I give a 10000 likes for your cuts and edits. Your videos are full of info (no lags and time waste). That itself proves you value your trade.. Kudos

don't understand why this video is not popular than it has to be. You are amazingly well explaining abstract concepts so dumb like me can understand. Thanks.

Very informative! Thank you very much for this fantastic explanation, and for presenting it in such a good-natured way!

This is quality man. Keep the good work, youtube definitly needs that. Well done

Fantastic series. When I get my first dev job I will do what I can to support you.

I love how you explained this. Very clear. 👏

This is the best explanation of a Singleton pattern ever !!

These videos are so precious thank you!

The way you jump entered, I expect to hear "Hey Vsauce" :P . Awesome video.

Not sure about other languages, but in C++, the preferred approach to singletons is known as the Meyers Singleton (named after Scott Meyers who included it in his book Effective C++). The idea is to declare the variable within a method rather than as a member variable. This is thread safe, and it also allows you to skip the check to see whether or not the singleton exists. The code looks like this: class Singleton { private: Singleton() {} public: static Singleton& getInstance() { static Singleton instance; return instance; } };

The best playlist (on IT/Sw) I have ever watched on RU-vid

You're views must really go up every December/January. Exams time and your explanations are great, thanks man

Just wanted to let you know that you are amazing for making this series!

Thanks, your explanation was clear and convincing :)

Thank you for making this series ❤❤❤

The best explanation of Singleton pattern i have come across

As much as we try to avoid Singletons, we do run into scenarios where we have to use one. Specially when working with native Android using Java where for creating Fragments, we use a public Instance property to get access to it. These Instances are then held in memory for various operations done by the OS. Great series, keep it up :)

Simplest and clear explanation I've come across. Thanks

great video. finally I found explanation in a style that I can understand clearly. Thanks for the lesson. I am now a subscriber.

Great video! However, the argument is not that Singletons are necessarily bad except that they are misunderstood, often abused and can introduce unwanted side effects when used without proper thought -- a lot of frameworks use Singletons :D. For instance, I have this piece of (framework) code that manages all of my configurations (and of subsystems) and the construction of this object is really heavy and doesn't even lend itself to a prototype or flyweight. It is important that these bits of configuration happen only once at application startup. Instead, I hide my singleton configuration instance behind an abstraction and delegate the construction and life cycle to a DI / IOC container. In other words, users only have to depend on that abstraction e.g. IConfigurationManager etc. In addition, the one thing (or two) I think you're missing is the issue of potential race conditions or thread-safety in concurrent systems when handling stuff like this manually -- why it's important to use a good DI framework and instead depend on abstractions. Plus, it is your responsibility to ensure that your object is IMMUTABLE upon construction and member access is read-only.

A clear video on single ton design pattern. Thank you.

i got a UML exam tomorrow , and i've been watching your video , your videos are saving my life right now

you have really simplified design patterns ... classic explaination ... thank you very much

I have watched all your videos on Design Pattern, You rock!!! keep up the good work. :)

One of the best video series I have ever seen. Superb explanation. Quite like the way you do these videos in your own style. Keep up the good work. P.s. loved ur writing and honesty :P

Hey SIr , I am Sri Lankan IT Undergraduate , you do explain these design patterns very well and Thank You So much. It was really helpful me to figure out the answers for the design patterns questions in our university :)

Woooow, Thanks christopher for this wonderful series. Your teaching style is awesome. waiting for other design patterns :)

Thanks Christopher! I will definitely check out those links. On to the next pattern :)

Clear, audible video. Keep it up

Very nice and detailed explanation of design pattern concepts.... I am waiting for other remaining design patterns videos ..... Thank you very much.

NIce man, totally grasped for the first time, thank you so much.

Super awesome mate. Clear explanation.

Super clear! Thanks Christopher!

Thanks a lot! Very cool vivid explanations and examples! Thanks! Thanks! Thanks!

god bless you, christopher. Please keep making videos!!

Your explanation of concepts are easy to understand 👏👏👏👏👏

thanks again Christopher. your videos are great

had to add - you are amazing! great vids once again Thank you.

Excellent i have a java architecture certificate exam within 3 months. You made me clear with the design pattern. Many thanks. Bless you

Gooooooooood one !!!! Very clear ! Clear all my concepts !

such a wonderful lecture . concept clear now.

Excellent. easy to understand. Thank you.

Great Series...Thanks for making those video ... waiting for more videos.

Thank you! Good points. The only time I have used a Singleton is when I was developing my own small website, wanted a quick cache, and only needed to load the database once at application startup to save on Cloud Database DTU hits. The webpage did load faster using the Singleton as a cache. A static class also worked for this scenario and is a little more straightforward. Either was ok for this scenario because I only changed the data about once per month, could restart the application when I wanted, and didn't have sessioned users on the site yet. However, once I want to add/change data in the database and want to reset the cache without an app restart, it is a dead-end; so it is not practical for many business production scenarios. I was just looking at 5-6 ways to cache and those were the quickest but most limited.

Dude I really love your videos! Keep up the great work :)

Oh my god, you are a good explainer! I'm actually understanding what's happening

Thanks Christopher really your explanation is very good

This is perfect. Thank you so much.

definitely a very simple to understand explanation, thank you. I would as "a novice" suggest there are legitimate uses for singletons in game development.

just subscribed ur channel ! love the way you teach !

Dude ! am waiting for command design pattern :) you are awesome , i just love the way u make everything easier and understandable :)

thanks chrostoper the best video about singleton i ever watched

BEST VIDEO EVER!!!!! So much better than university lectures

You are a great instructor. Keep it up please.

very good explanation of Singleton. Thanks Christopher

Superb man, you explained very well. I really got lot of interest on design patterns. Thank you so much I leant a lot from your video's.

Brilliant work - thank-you.

Liked the way you describe different aspects of decision making and assumptions related to pattern

That was great! thank you 🙌

I was waiting for this one :) wow it's wonderful

Love u sir, U make design pattern so easy

It’s very helpful, thanks

Clearly explained ! thank you .

Amazing work on patterns, reading book is fine, but all those extra explanations are just making everithing perfectly fit in place. Wish you could finish rest of book till monday when i have test out of all patterns from book ^.^ Any way, keep it up (sharing videos with rest of Uni, everyone is gratefull)

Best explanation, thanks a lot

Thank you for your videos !

Thank's for all the Knowledge🤜

Excellent explanation Cristopher! Only one thing to note: what happens in a multi-threaded environment? It may happen that two different threads call the getInstance() method and because of this, more than one instance of the Singleton class is created. The only way to ensure a single instance is to add the synchronized in the getInstance method signature or (it would be better), synchronize the block of code in which we check if the instance is null (the if statement). Congrats for your videos!

this amazingly amazing , thankyou brother.

Singleton can be used in notification servers for mobile devices or others, when you always have one and only one instance to call to add or remove observers. :) thx Christopher Okhravi for clearing this out!

Thanks for the great video! Now I found one more interesting place to visit on youtube :)

watching keenly!

I love Singleton in Unity. Very handy for Manager objects.

Explained well thanks buddy 😊

Very good explanation.. really help for me..