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Gameplay/AI programmer.
Write about game programming, Unreal Engine and C++

Enums as name

Published on 24 Mar 2024

Enums

Technically, enum type is a set of predefined constants.

So it is a good practice, that you use it as set of options. But there is a problem in Unreal, that a lot of things could be used only with strings. For example, sockets.

Imagine, you have actor that do some stuff related do components and sockets. So you create enum:

UENUM(BlueprintType)
enum class EMyComponentSocket : uint8
{
    BottomSocket,
    MiddleSocket,
    TopSocket,
};

And now you need attach something to socket with name TopSocket. Also, you would like to use name as map key in blueprints properties. So you want to use enum, instead of hardcoded string. But how to?

GetAuthoredNameStringByValue()

The best way to do it - to use authored functions.

They returns the unlocalized logical name originally assigned to the enum at creation. By default it is short name, but it could be overriden in child classes with some internal names. This name is consistent in cooked and editor builds. So it will guarantee that it wil returns same name whole time.

FString EnumString = StaticEnum<EMyComponentSocket>()->GetAuthoredNameStringByValue(static_cast<int64>(EMyComponentSocket::TopSocket));

FName EnumName = FName(*StaticEnum<EMyComponentSocket>()->GetAuthoredNameStringByValue(static_cast<int64>(EMyComponentSocket::TopSocket)));

FString FoundEnumName;
bool EnumNameWasFound = StaticEnum<EMyComponentSocket>()->FindAuthoredNameStringByValue(FoundEnumName, static_cast<int64>(EMyComponentSocket::TopSocket));

//They all returns "TopSocket"

Also there are no-authored versions. But you should AVOID them, if you want to use your enums as strings, because they could be changed by reflection.

StaticEnum<EMyComponentSocket>()->GetNameStringByValue(static_cast<int64>(EMyComponentSocket::TopSocket));

//Don't use it
//You can never be sure that it will return the same value in build and editor

Examples

FName SocketName = FName(*StaticEnum<EMyComponentSocket>()->GetAuthoredNameStringByValue(static_cast<int64>(EMyComponentSocket::TopSocket)));

MyComponent->AttachToComponent(RootComponent, FAttachmentTransformRules::KeepRelativeTransform, SocketName);

UPROPERTY(EditDefaultsOnly, Category = "Sockets")
TMap<EMyComponentSocket, TSubclassOf<AActor>> SocketsActors;

for (TTuple<EMyComponentSocket, TSubclassOf<AActor>> SocketsActor : SocketsActors)
{
    AActor* SpawnedActor = GetWorld()->SpawnActor(SocketsActor.Value);
    
    FName SocketName = FName(*StaticEnum<EMyComponentSocket>()->GetAuthoredNameStringByValue(static_cast<int64>(EMyComponentSocket::TopSocket)));
    SpawnedActor->AttachToActor(this, FAttachmentTransformRules::SnapToTargetNotIncludingScale, SocketName);
}

And many many others.

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