UCLASS type

The uClass macro

The uClass macro is used to define a UCLASS in Nim - equivalent to the UCLASS macro in C++.

uClass AMyNimActor of AActor:
  uprops:
    myInt: int32
  ufuncs(CallInEditor):
    proc myFunc() =
      log "Hello from Nim"

The uClass allows for using uprop and ufuncs macros to define properties and functions of the class.

The default keyword

uClass AActorChild of AActorParent:
  (Blueprintable, BlueprintType)
  uprops(EditAnywhere):
    test12 : FString

  default:
    primaryActorTick.bCanEverTick = true
    primaryActorTick.bStartWithTickEnabled = true;

The override keyword

uClass ANimBeginPlayOverrideActorChild of ANimBeginPlayOverrideActor:
  (Blueprintable, BlueprintType)
  uprops(EditAnywhere):
    test12 : FString

  default:
    primaryActorTick.bCanEverTick = true
    primaryActorTick.bStartWithTickEnabled = true;

  override:
    proc beginPlay() =
      UE_Warn "Native BeginPlay called in the child!"
      super(self)

    proc isListedInSceneOutliner() : bool {. constcpp .} =
      UE_Log "IsListedInSceneOutliner called in the child"
      self.super()

    proc canEditChange(inProperty {. constcpp .} : FPropertyPtr) : bool {. constcpp .} =
      UE_Log "CanEditChange called in the child updated 1"
      self.super(inProperty)

The uConstructor pragma

You can define custom constructors for classes:

proc myExampleActorCostructor(self: AExampleActorPtr, initializer: FObjectInitializer) {.uConstructor.} =
  UE_Log "The constructor is called for the actor"
  self.anotherVale = 5

  #you can override the values set by the default constructor too since they are added adhoc before this constructor is called.
  self.predValue = "Hello World"