Implementing abstract derived events

Development Programming & Scripting
1

I have a C++ base class defined as followed:

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Character.h"
#include "Engine/DataTable.h"
#include "SoulforgedCharacterBase.generated.h"

UCLASS(ABSTRACT)
class SOULFORGEDCHARACTER_API ASoulforgedCharacterBase : public APawn
{
	GENERATED_BODY()
	
protected:
	// Called when the game starts or when spawned
	virtual void BeginPlay() override;

	UPROPERTY(EditDefaultsOnly, BlueprintReadOnly, Category = Animation, meta = (AllowPrivateAccess = "true"))
	UDataTable* ActionMontages;
	
public:

	DECLARE_EVENT(ASoulforgedCharacterBase, FCharacterDiedEvent);
	virtual FCharacterDiedEvent& OnCharacterDied() = 0;

private:
    // remainder of private definitions

and then a derived class as:

#pragma once

#include "CoreMinimal.h"
#include "SoulforgedCharacterBase.h"

// Additional Engine includes
#include "EngineGlobals.h"
#include "HumanoidSoulforgedCharacter.generated.h" //Must be last

/**
 * 
 */
UCLASS()
class SOULFORGEDCHARACTER_API AHumanoidSoulforgedCharacter : public ASoulforgedCharacterBase
{
	GENERATED_BODY()

public:

	void Tick(float DeltaTime) override;

	DECLARE_DERIVED_EVENT(AHumanoidSoulforgedCharacter, ASoulforgedCharacterBase::FCharacterDiedEvent, OnCharacterDied)
	virtual FCharacterDiedEvent& OnCharacterDied() override { return CharacterDiedEvent; }

protected:

private:
	FCharacterDiedEvent CharacterDiedEvent;
};

I came up with this following the documentation found here

the event declarations produce the following errors: object of abstract class type ASoulforgedCharacterBase is not allowed: function "ASoulforgedCharacterBase::OnCharacterDied is a pure virtual function i’ve tried a few different variations to no avail. Can I get some guidance on what I’m doing wrong?

2

Compiler interpates virtual FCharacterDiedEvent& OnCharacterDied() = 0; as const function which also called pure function that don’t change state of object. So function as a function with different data structure and compiler considers your override as overload attempt instead. As result since override was not completed, base abstract class inherence is not fully fulfilled and compiler treats your new class as abstract too (as abstract classes are not explicitly declared in C++as such, the UCLASS thing is only information for UE4 reflection system captured by UHT), thats why it say you can not create object of abstract class but also detected possibile error you made. So to properly override your function you need to add const at the end of function deceleration to declare it as a pure function:

virtual FCharacterDiedEvent& OnCharacterDied() const override { return CharacterDiedEvent; }
3

So i’ve tried a few things, including your change and I can’t get my source to compile, even without the derived class overriding the base class event. I still get the above errors.