Design Pattern: Singletons in Unity

[@samyam]

When thanking my new patrons at the end I made a mistake and somehow replaced one of the images I made with the thumbnail 😔 Thank you to Thomasz in the Enthusiastic Tier for your support! ⭐️

[@tauheedgamedev2388]

Great tutorial, I'v been using Singletons for a while but with the level of detail in this tutorial I still learned some things. Thanks 👍

[@Patricebrouh]

Wow, your explanation is so clear. I can say : "Brackeys has gone, thanks to God we have another Brackeys" .

[@samyam]

I have a long way to go to get to Brackeys level 😄

[@marushirudesu]

@@samyam you don't have be brackeys, you have to be samyam that can be better than brackeys.

[@chris.davidoff]

This was really informative! I personally do the persistent scene for different things (Like UI, which I may want to unload in cutscenes and such)

[@lemetamax]

This is a really awesome video on singletons, I can't believe I've been using it wrongly. I'll have to watch again to understand it tho.

[@leonardo6631]

Great video! Thanks for the nice content ❤️

[@syngleton]

Sam, this tutorial is incredibly helpful and has completely changed the way I implement this design pattern. The one problem I have with this is I don't know how I'd be able to have a class derive from a base class but also inherit from your Singleton class. The only way I could think of achieving something like this is by turning your Singleton class into an interface, but it doesn't seem like the best approach to me, considering I'd probably have to keep overriding the Awake() and OnDestroy() methods when creating new classes implenting this interface. What would you suggest?

[@samyam]

Glad you enjoyed it! Hmm maybe you can make a parent empty GameObject as the singleton container for the other game object which derives from that other class? Something like this: Parent.Instance.GetChild()....

[@diazpsp]

What is your font in the VSCode? looks nice

[@clc4333]

aspiring game dev, just at the very beginning stages... couldn't understand this part, so i'll check out some more easier material then come back!

[@SubjektDelta]

If I wanted to have an object in the scene how could I set it to the instance itself? My problem currently is that I have a manager object in the scene and when some other script tries to use the instance a new one is created.

[@ericwoodworth8079]

ArgumentException: SceneManager.SetActiveScene failed; scene 'Managers' is not loaded and therefore cannot be set active. I've looked over this video many times to make sure I had everything done the same way as you do. My scene is in the build settings properly. Is there something I am missing?

[@samyam]

Perhaps because the scene is still loading while you are trying to access something. You should wait a frame to make sure it's loaded before accessing the value. You can load it in a coroutine IEnumerator LoadSceneCoroutine(string pSceneName){ yield return SceneManager.LoadSceneAsync(pSceneName); // do something with the scene }

[@ericwoodworth8079]

@@samyam Awesome! Thanks, I am going to give it a shot

[@jorgevalles6835]

In my job I entered in a nightmare due to Singletons. We reached a point in which literally everything you can imagine was a Singleton ☠. So we started to loose control on initialization and closing of several systems, specially when changing scenes. Lots of things crashing because of requests to singletons that will start working in other scene. :(

[@danielbezerra5650]

Thank you 🙏🏿

[@lucky4the4turtle]

So uuuh, dumb question, but at 4:48 on line 3 what does do wtih the SinglePatternPersistent class? Edit: Nevermind I should have just kept watching the vid.

[@ninqbi1738]

i dont understand why you put an "inputManager" obj in Managers scene beforehand. Cause as your scripts, it will generate an T object when we firstly start the game. Can u explain it?. Anyway, this is good tutorial, thks

[@fernandomilans8444]

Hi! could you enable the subtitles? thanks!

[@samyam]

Hi I'm not sure why it wasn't enabled... For some reason it didn't generate the subtitles automatically. I tried re clicking the language but a video online said it might take some time to show up if it's able to generate it. Sorry ☹️

[@candle-likeghost9523]

Urm.... in 11.03. I need to point out that the "public static T Instance { ...." is not a function but a property. and instead of DontDestroyOnLoad(this), we can do DontDestroyOnLoad(obj), right? (Since Unity destroy the game object with the script when loading, we just need to tell Unity to not destroy the game object when loading).

[@samyam]

Yes you are correct, however it won't be persistent if no other script calls it's Instance since it will only create the gameobject once it's called. But if you put it in the Awake it is guaranteed to be persistent even if no other script calls it.

[@candle-likeghost9523]

Oh I see, thanks for explaination

[@kendrickjba]

I'm getting this error "ArgumentException: SceneManager.SetActiveScene failed; scene 'Managers' is not loaded and therefore cannot be set active"

[@kendrickjba]

I fix it calling the input manager on start instead of calling it on awake on my player script

[@zlisarew6830]

I have an issue if I go from scene 1 to scene 2 it will load the Managers scene then if I go back from scene 2 to scene 1 it will load another Mangers scene because Awake() in scene 1, I fixed it by checking if (!Managers.isLoaded) then load Managers scene

[@samyam]

Because it has a Do not Destroy and it keeps it alive during other scene managers. You need to check if there is already another instance running before starting a new one

[@arunachalpradesh399]

please reply. how can sound manager be as singleton, as everyone says. because singleton gurantees only one class can acess singleton class at a time. what if sound manager contains gun shot sound, which both player and enemy fire at same time. so how can both players and enemy class access singleton at same time.

[@WildPork]

"because singleton gurantees only one class can acess singleton class at a time" this isn't true unless you have used a "lock" to restrict access.

[@youcancallmedoggie]

Amazing video! helped me a lot, but i have a question, how to stop persistant scenes loading more then once, like when i restart that scene?

[@samyam]

The singleton will check if an instance already exists and if so not load the extra object. You can make a manager for that persistent scene a singleton.

[@vmmi8215]

I've been travelling through some of your video, i can say that you indeed have a really deep understanding about clean & good code, i hope that you would make a video about things to learn for beginner or intermediate to mastery the code principles such as SOLID principle But anyway, i love your lovely voice 😍👍

[@samyam]

Thank you so much!! I’m hoping to make tons of tutorials more in the future! :)

[@playplus5386]

People keep saying that this is a good tutorial, maybe it is, but I'm here to learn the Singleton pattern. However, now I'm confused about the new Unity input system, flags, and many other concepts. Please make a simple scene and focus on the subject: the Singleton pattern. In order to fully understand your tutorials, I have to go back and learn those concepts first, and then come back here. I feel like I'm wasting my time

[@LostSol25]

how long have you been doing game dev? and are you currently working in the industry?

[@samyam]

Around 6 years! No I'm doing my own stuff :)

[@LostSol25]

@@samyam thats super cool! Thanks and keep going with your tutorials they are amazing!!

[@samyam]

Thank you! 😄

[@SaadTheGlad]

Hello! Do you know of a simpler tutorial? I'm just trying to get my references to stay correct after switching scenes but I don't know where to start learning... :(

[@samyam]

Here’s a tut by Infallible Code on Singletons kzbin.info/www/bejne/o6GwYXZsptqEoNU What’s the issue? Make sure you have DoNotDestroy on your singletons so that it persists through your different scenes. However gameobjects in that new scene still need that reference Class.Instance

[@SaadTheGlad]

@@samyam Thank you! I have fixed my issue with the dialogue system (parented all the UI elements and the player to a don'tdestroyonload) but a new problem arose: proper level system. I wanted to make one like undertale but there are no tutorials on the subject...

[@samyam]

Like leveling up? Code Monkey has an in depth video here kzbin.info/www/bejne/oXymfYCsqMx0iJI

[@piggeh6465]

Sam can you do animation movement tutorial for isometric? there's like no videos on the subject :(

[@samyam]

This video might help kzbin.info/www/bejne/qqrapWyqhNqVe7s But I'll put it on my list for future videos!

[@piggeh6465]

Thanks :)

[@CyberAngel67]

I have to ask, why is a singleton hard to test? Proper written Unit Tests can cover a singleton.

[@samyam]

If your unit test is self contained and you use dependency injection in your code to avoid strongly coupling your singleton instance with a class then it can work fine. But you have to architect your code in a certain way to achieve this, which many game developers generally do not. See: testing.googleblog.com/2008/05/tott-using-dependancy-injection-to.html

[@AndyScott67]

@@samyam I disagree with that, I have worked in developing Applications with patterns like AOP, DI to name a few. These can all be mocked, and is a major part of doing Unit Tests.

[@CCV334]

Why unload the current scene and not just load the new scene. If you load a new scene doesn't it just override the current one. The singleton would also have a DontDestroyOnLoad so why would you need to write anything to load it additively?

[@moncicis]

the subtitle is awful