Access Blueprint Function Library in C++

Development Programming & Scripting C++
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10

You can get an instance for function libs, it’s the class default object.

I also tried various attempts at creating an intermediate C++ BFL with an override-able/implementable BP function, but no luck so far.

A simpler way would be to turn functions into member functions, and provide an accessor. No need to manage an instance since there’s already the CDO. You just need a variable somewhere to hold a reference to the BP version of the lib.
For example

UCLASS(Blueprintable, Abstract)
class UBFL_Test : public UObject
{
    GENERATED_BODY()

    UPROPERTY()
    UClass* BpLibClass;

    UBFL_Test()
    {
        static ConstructorHelpers::FClassFinder<ThisClass> BpLibAsset(TEXT("/Game/BP_BFL_Test"));
        if (BpLibAsset.Succeeded())
        {
            BpLibClass = BpLibAsset.Class;
        }
    }

public:
    UFUNCTION(BlueprintPure)
    static ThisClass* Get() { return BpLibClass->GetDefaultObject<ThisClass>(); }

    UFUNCTION(BlueprintCallable, BlueprintImplementableEvent)
    void PublicMethod();
};

The referenced asset at /Game/BP_BFL_Test would be a blueprint child class of UBFL_Test which implements the methods.

Of course it would be better to reference it in a BP-assignable variable such as in a GameInstance subclass. FClassFinder is more of a prototyping temporary solution.

You could even make a wrapper for each function to make it entirely transparent for the blueprints side, but that might get quickly cumbersome, like so

UFUNCTION(BlueprintImplementableEvent) //not callable
void PublicMethodImpl();

UFUNCTION(BlueprintCallable)
static void PublicMethod() { return Get()->PublicMethodImpl(); }