Implements multiple functions with an interface

Development Programming & Scripting C++
1

Using the sample provided from here:
https://wiki.unrealengine.com/Interfaces_in_C%2B%2B

The provided sample works fine by itself, but if I simply add a “ReactToSunset()” function, this won’t work out with flower.h(or frog.h).

ReactsToTimeOfDay.h – added ReactToSunset()


#pragma once
 
#include "ReactsToTimeOfDay.generated.h"
 
/* must have BlueprintType as a specifier to have this interface exposed to blueprints
   with this line you can easily add this interface to any blueprint class */
UINTERFACE(BlueprintType)
class MYPROJECT_API UReactsToTimeOfDay : public UInterface
{
	GENERATED_UINTERFACE_BODY()
};
 
class MYPROJECT_API IReactsToTimeOfDay
{
	GENERATED_IINTERFACE_BODY()
 
public:
	//classes using this interface MUST implement ReactToHighNoon
	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "MyCategory")
		bool ReactToHighNoon(); 

	//classes using this interface MUST implement ReactToSunset
	UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "MyCategory")
		bool ReactToSunset();

	//classes using this interface MAY implement ReactToMidnight(using blueprint only)
	UFUNCTION(BlueprintImplementableEvent, BlueprintCallable, Category = "MyCategory")
		bool ReactToMidnight();
 
};

ReactsToTimeOfDay.cpp – Unchanged


// Copyright 1998-2013 Epic Games, Inc. All Rights Reserved.
 
#include "MyProject.h"
#include "ReactsToTimeOfDay.h"
 
UReactsToTimeOfDay::UReactsToTimeOfDay(const class FObjectInitializer& ObjectInitializer)
	: Super(ObjectInitializer)
{
 
}

Flower.h – added ReactToSunset() and ReactToSunset_Implementation()


//..other includes may appear here depending on your class
#include "ReactsToTimeOfDay.h"
#include "ASkeletalMeshActor.generated.h"
 
UCLASS()
class AFlower : public ASkeletalMeshActor,  public IReactsToTimeOfDay
{
	GENERATED_BODY()
 
public:
	/*
	... other AFlower properties and functions declared ...
	*/
 
	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "MyCategory")
		bool ReactToHighNoon();
		virtual bool ReactToHighNoon_Implementation() override; 

	UFUNCTION(BlueprintCallable, BlueprintNativeEvent, Category = "MyCategory")
		bool ReactToSunset();
		virtual bool ReactToSunset_Implementation() override; 
 
};

Flower.cpp – added ReactToSunset_Implementation()


//other flower.cpp code
 
bool AFlower::ReactToHighNoon_Implementation()
{
	//Default behaviour for how flower would react at noon
	//OpenPetals();
	//AcceptBugs();
	//...
 
	return true;
 
}

bool AFlower::ReactToSunset_Implementation()
{
	//Default behaviour for how flower would react at sunset
	//DoStuf()
	//...
 
	return true; 
}

I get this error message in VS:

I tried to come out with different signature for ReactToHighNoon and ReactToSunset(with a different return value type and different number of parameters), butI still get the exact same messsage error.
What’s going on?

(Note: I’m using Unreal 4.15.3)

2

I found the culprit. Actually I used a function called “ReceiveHit” instead of ReactToSunset… I believe the function name “ReceiveHit” was already reserved for something else.