Need help with weird static variable behaviour c++

[ThaGureatestBoi]

Hi, I have a game where I have a class Pattern where I want all my instances to have the same grid (Represented as a TArray<TArray<GridElement*>>).

So I have tried to make two static variables , one for the grid and another bool “Initialized” to be sure to only initialize and fill once the Grid.
In my static getter I call an Initializer function if my bool "Initialized " is at false and in that function I set “Initialized” to true;

When I try my game in the editor, the first try works as intended no problem.
If I stop my simulation and start it again I start to lose some informations on each of the GridElement * AND "Initialized " is already set to true and each restart I lose more informations until I fully restart the editor

Here is a part of my .h

UCLASS(Abstract, Blueprintable)
class USharpPattern : public UPattern
{
	GENERATED_BODY()

public:
	USharpPattern();
	static bool Initialized;
	static void Init() ;
	static TArray<TArray<UCraftBox* >> CraftBoxes;
...

And Here is my .cpp declaration of my variables

TArray<TArray<UCraftBox*>> USharpPattern::CraftBoxes;
bool USharpPattern::Initialized = false;

It is the first time i’m using static variables so I would like to know if someone know where the problem lies

Thanks a lot.

[rokenrock]

Yup- static does that.
Static variables stick around even after you end the game- you have to completely exit the engine for them to clear.

Try to avoid using static unless you can deal with them using non-static variables.
Ie a singleton that you override (don’t check if the pointer is valid) or a subsystem (they have managed life-times).

[IrSoil]

c++'s statics will be global for editor and all pie sessions, that’s why your Initialized is true. But also, as you can see:

I start to lose some informations on each of the GridElement*

your GridElement*s are killed by garbage collector since your array isn’t an UPROPERTY() (and iirc you can’t mark static variable as UPROPERTY())

As for solution, i like the answer from this thread: Singleton pattern in c++ - #2 by smugdev - don’t use c++'s singletons and use ue’s local “singletons” from gameplay framework.

all my instances to have the same grid

Depending on exact goals, something like GameMode, GameInstance, GameState or as said in other comment Subsystem - makes sense. You can create a single USharpPattern* (or just an array of UCraftBox’es) here and use it when you create instance of object or whenever you need it.

[ThaGureatestBoi]

Oh, I wasn’t aware of that.

Since the behaviour is intended I will search through the different possible solutions
Thanks for your answers

[IrSoil]

behaviour is intended

I’d like to clarify, that’s not that it’s intended, but it’s a logical consequences of language structure.

Also worth mention that c++'s statics will work properly in packaged game(as long as pointers you storing are protected from GC by any way), as there is no editor attached, so they are not completely out of question (though their usefulness is limited), but it’s just a real pain to debug them in editor.