Download

Problem with TActorIterator<AnyType> In Custom "MyPlayerController.cpp"

Development Discussion C++ Gameplay Programming
#1

I recently upgraded to 4.18 from 4.15. I have now encountered a problem with the TActorIterator, only inside AMyPlayerController it seems.

The error I get looks like this:


void AMyPlayerController::BeginPlayingState() {
      Super::BeginPlayingState();

       AMyTank* NewTank = Cast<AMyTank>(GetPawn());
      for (TActorIterator<AMyTank> TankIt(GetWorld()); TankIt; ++TankIt) {
                //Body
   }
 }

There is an error when I try to do TActorIterator with the following error log:


2>c:\program files\epic games\ue_4.18\engine\source\runtime\engine\public\EngineUtils.h(490): error C2664: 'TActorIteratorBase<TActorIterator<AMyTank>>::TActorIteratorBase(TActorIteratorBase<TActorIterator<AMyTank>> &&)': cannot convert argument 2 from 'TSubclassOf<AMyTank>' to 'TSubclassOf<AActor>'
2>  c:\program files\epic games\ue_4.18\engine\source\runtime\engine\public\EngineUtils.h(490): note: No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
2>  c:\program files\epic games\ue_4.18\engine\source\runtime\engine\public\EngineUtils.h(488): note: while compiling class template member function 'TActorIterator<AMyTank>::TActorIterator(UWorld *,TSubclassOf<AMyTank>,EActorIteratorFlags)'
2>  C:\..\..\Player\MyPlayerController.cpp(426): note: see reference to function template instantiation 'TActorIterator<AMyTank>::TActorIterator(UWorld *,TSubclassOf<AMyTank>,EActorIteratorFlags)' being compiled
2>  C:\..\..\\MainFiles\Source\PC\Player\MyPlayerController.cpp(426): note: see reference to class template instantiation 'TActorIterator<AMyTank>' being compiled

I did this same function in another class, in a class that extends UMG Widget, and it worked fine as of now - sometimes it didn’t work either, but it seems to consistently work now. But, now the error happens in this custom Player Controller class. If anyone has any information about this, I am all ears.

#2

Just a wild guess, due to the engine change the order of includes have changed in your build. Do you include the AMyTank header file in the AMyPlayerController?

#3

I didn’t originally. I tried adding it in the header file, and I still receive the same error. Strange enough, I received this error in my other class - in the widget - that uses this. I was able to fix it there by including AMyTank in the header, but not in AMyPlayerController.

EDIT: It only works if I do TActorIterator<AActor> in AMyPlayerController. Could this be a bug?

#4

Does the same happens with TObjectIterator<AMyTank> ?!

#5

TObjectIterator<AMyTank> works but is not what I want. It seems to go through all instances of Tank created throughout the entire instance of the game - from what I understand. I want to iterate through the current actors though, not objects that have been made in the past.

It just seems to not work in the PlayerController for some reason.

#6

Maybe someone did ‘optimizations’ to the function and broke usability, happens all the time.
People touching this area of the engine doesn’t read the forums so you’d have to file a bug report on AnswerHub + GitHub and hope anybody notices.

#7

Can you show us the declaration of the AMyTank class, just to be sure.

#8

If anyone else runs into this issue, the problem for me was there was already a


#include "Engine/World.h"

, which forward-declares TActorItr but doesn’t fully declare it. You have to


#include "EngineUtils.h"

to get the full declaration.