[Bug Report?] UFunction return of references

Development Programming & Scripting Blueprint
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1

Hello there,

im not sure if this should be considered as a bug report, but i experience some problems when trying to
return a const Reference of a variable instead of a copy as soon as it is declared as a UFUNCTION().

Example

const TArray< SomeThing >& GetAllOfSomething()

complains about wrong direction for the output pin in blueprint.

I believe this might be related to the opportunity for blueprint nodes to have more than one return values, since
if you add references as variable types as params, you´ll get output-pins of those params in the blueprint node.

Example:

void ToastMeSandwich(FSandwich &Sandwich)

Will this be possible some other time? or do we have to live with returning unsafe references?

best regards

2

Hey -

If you are trying to write code to use as a blueprint then the syntax for returning an array is a little different than expected. Using the “Get All Actors of Class” node as an example the return type for the source code of this node is actually void:

void UGameplayStatics::GetAllActorsOfClass(UObject* WorldContextObject, TSubclassOf<AActor> ActorClass, TArray<AActor*>& OutActors)
{
	OutActors.Empty();

	UWorld* World = GEngine->GetWorldFromContextObject(WorldContextObject);

	// We do nothing if not class provided, rather than giving ALL actors!
	if(ActorClass != NULL && World != nullptr)
	{
		for(TActorIterator<AActor> It(World, ActorClass); It; ++It)
		{
			AActor* Actor = *It;
			if(!Actor->IsPendingKill())
			{
				OutActors.Add(Actor);
			}
		}
	}
}

The important part of the syntax is TArray< AActor>& OutActors as this is what controls the output pin in blueprints. With this in mind you can simplify the parameter to TArray& VARIABLE to use a different name or different datatype.

Ex: The following will produce a node with an input target of Self and output an array of floats when called in blueprints:

UFUNCTION(BlueprintCallable, Category = Test)
		void GetAllOfSomething(TArray< float >& OutFloat);

Cheers

3

Hello there,

thanks for the information and the fast reply.

This can be marked as solved then :wink:

Btw. everytime i post something i am not able to respond with comments, i only am able to “answer”. Did i miss some setting for that?

best regards

4

When you click the “Post you answer” button you should be prompted if your response is an answer or a comment. You should also see an “add new comment” button under the display name for each post.

5

yes, thats exactly what im looking for. In other posts i can do it easily but not in my own. There is also no reply under your comment visible for me, thats why “this” is an answer again.

6

Hello!
This works indeed, but if I want to pass an

TArray& val

as input?

7

Hey, i guess you would need to pass in a pointer instead.

So TArray* val should work to give you an input pin in blueprint.