Hello I’m struggling to get interface inheritance work. I simplified the problem, let’s say that we have this interface:
UINTERFACE(BlueprintType)
class UAInterface : public UInterface
{
GENERATED_BODY()
};
class IAInterface
{
GENERATED_BODY()
public:
UFUNCTION(BlueprintNativeEvent, BlueprintCallable)
void OnSomething();
Now this component that implements the interface prints the HELLO WORLD text:
UCLASS(Blueprintable, BlueprintType)
class UComponentA: public IAInterface {
GENERATED_BODY()
public:
virtual void OnSomething_Implementation() override {
UE_LOG(LogTemp, Warning, TEXT("HELLO WORLD"));
}
};
Now the concrete component that inherits from UComponentA and extends the functionallity:
UCLASS(Blueprintable, BlueprintType)
class UComponentB: public UComponentA {
GENERATED_BODY()
public:
virtual void OnSomething_Implementation() override {
HOW TO CALL THE INTERFACE FUNCTION OF THE SUPER CLASS (UComponentA) to output first the HELLO WORLD text???
//Super::OnSomething(); <-- this crashes with: Do not directly call Event functions in Interfaces. Call Execute_OnSomething instead
// If I use Execute_OnSomething( UObject* ) it needs a pointer to the Super class i think.. how to retrieve it?
UE_LOG(LogTemp, Warning, TEXT("I'M THE COMPONENT B!!! "));
}
};
Is the red line possible to do? How exactly?
Thank you!
Maybe taking a look into any UE class source code might bring light to this, but from the look I think the decorator is not correct, it should be BlueprintImplementableEvent instead of BlueprintNativeEvent… Im not in a place where I can access the code, but I would look at how AActor code looks like as a reference.
When overriding _Implementation functions, you’re supposed to call Super::MyFunction_Implementation() - NOT Super::MyFunction(). If you don’t, bad things will happen. Try that first, and you won’t need the parameter either.
If that doesn’t work, then I don’t think it’s possible to call Super in an interface function exposed to Blueprint. C++ functions should work fine though, I think.
Calling the Execute function on a “Super Class” won’t really help you because A) it needs to be called on an instance, not a class - and B) you’ll end up calling it on a class-default object, not an instance of an object.
namespace UI
{
// valid keywords for the UINTERFACE macro, see the UCLASS versions, above
enum
{
/// This keyword indicates that the interface should be accessible outside of it's module, but does not need all methods exported.
/// It exports only the autogenerated methods required for dynamic_cast<>, etc... to work.
MinimalAPI,
/// Exposes this interface as an acceptable base class for creating blueprints. The default is NotBlueprintable, unless inherited
otherwise. This is inherited by subclasses.
Blueprintable,
/// Specifies that this interface is *NOT* an acceptable base class for creating blueprints. The default is NotBlueprintable, unless
inherited otherwise. This is inherited by subclasses.
NotBlueprintable,
/// Sets IsConversionRoot metadata flag for this interface.
ConversionRoot,
};
}
