Instantiate a UActorComponent subclass from a parametrized class in C++?

Development Programming & Scripting
1

I’m building a character in C++, and I want to have a weapon component which is instantiated from a class which can be set in blueprint. In my .h file I have this to parametrize the class:

/** Weapon class to spawn */
UPROPERTY(EditDefaultsOnly, Category="Weapon")
TSubclassOf<class UWeaponBaseComponent> InitialWeaponClass;

Then in the .cpp I am trying to instantiate like my other components, but it’s throwing an error:

MyCharacter::MyCharacter(const FObjectInitializer& ObjectInitializer):Super(const FObjectInitializer& ObjectInitializer)
{ 
     //...
    currentWeapon = CreateDefaultSubobject<InitialWeaponClass>(TEXT("InitialWeaponComponent"));
    //...
}

The error I get is No matching function to CreateDefaultSubobject.

So I guess InitialWeaponClass is not a class which can be passed to the template function CreateDefaultSubobject. What’s the right way to do this?

2

InitialWeaponClass is a member variable not a type name for a function template.

Try non-template version of CreateDefaultSubobject, here is an example:

	UPrimitiveComponent* CurrentWeapon = nullptr;
	TSubclassOf<UPrimitiveComponent> WeaponClass = UStaticMeshComponent::StaticClass();
	CurrentWeapon = Cast<UPrimitiveComponent>(CreateDefaultSubobject(TEXT("InitialWeaponComponent"), *WeaponClass, *WeaponClass, true, false, false));
1 Like
3

Thanks - doing it this way I’m no longer getting the compiler error. I am getting a runtime error though: it looks like my WeaponClass is still null in the constructor even though I’ve set a default for it in the blueprint.

So I guess the defaults set in blueprint are not available in the constructor? When do they become available, and when is the right time to use them?

4

Yep, properties are loaded later. Use this: AActor::PostInitProperties | Unreal Engine Documentation