Initialize components in C++ the correct way

Development Programming & Scripting
5

Testing after taking in account @KaidoomDev 's advice results in this correct code for defining components in C++ at build time:

// some .h file

class AMyCustomActor : public AActor
{
    GENERATED_BODY()

public:
    AMyCustomActor::AMyCustomActor()
    {
        Root = CreateDefaultSubobject<USceneComponent>(TEXT("SceneRoot"));
	    SetRootComponent(Root);
  
        SomeStaticMesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("SomeStaticMesh"));
        SomeStaticMesh->SetupAttachment(Root);
        
        SomeActorComponent = CreateDefaultSubObject<UActorComponent>(TEXT("SomeActorComponent"));
    };

protected:
    UPROPERTY(VisibleAnywhere, BlueprintReadOnly)
    TObjectPtr<USceneComponent> Root;

    UPROPERTY(VisibleAnywhere, BlueprintReadOnly)
    TObjectPtr<UStaticMeshComponent> SomeStaticMesh;

    UPROPERTY(VisibleAnywhere, BlueprintReadOnly)
    TObjectPtr<UActorComponent> SomeActorComponent;

    // ...

And at runtime, the following works:

    // the `FName` needs to be unique, therefore I construct it using the loop index `i`
    const auto SplineMesh = NewObject<USplineMeshComponent>(this, *FString(TEXT("SplineMesh")).Append(FString::FromInt(i)));
    // if I don't register here, the spline mesh doesn't render
	SplineMesh->RegisterComponent();
	SplineMesh->AttachToComponent(Root, FAttachmentTransformRules::KeepWorldTransform);
	// if I don't add instance here, the spline meshes don't show in the component list in the editor
	AddInstanceComponent(SplineMesh);
		
    // specific set up of spline mesh component
	SplineMesh->SetMobility(EComponentMobility::Stationary);
	SplineMesh->CastShadow = false;
	SplineMesh->SetStaticMesh(SM_Trajectory);
	const auto VecStartPos = Spline->GetLocationAtSplinePoint(Indices[i], ESplineCoordinateSpace::World);
	const auto VecStartDirection = Spline->GetTangentAtSplinePoint(Indices[i], ESplineCoordinateSpace::World);
	const auto VecEndPos = Spline->GetLocationAtSplinePoint(Indices[i + 1], ESplineCoordinateSpace::World);
	const auto VecEndDirection = Spline->GetTangentAtSplinePoint(Indices[i + 1], ESplineCoordinateSpace::World);
	SplineMesh->SetStartAndEnd(VecStartPos, VecStartDirection, VecEndPos, VecEndDirection);
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