Forward declare a class

Development Programming & Scripting
1

I have two classes. ABalloon and ABalloonGenerator. The generator drops balloons so it needs “Public/Balloon.h” and the balloon needs to get some information from the generator so it needs “Public/BalloonGenerator.h” but you cannot have the headers including each other or you get recursion.

How do I forward declare a pointer to the class so that I can get all the publics (vars, functions, etc.) from each class in the other class??

Let me know if this is not clear enough.

2

Forward declaration does not include any knowledge about publics (vars, functions, etc.), the only thing it does is to tell the compiler that you have a class/struct/enum of that type defined somewhere else.

And just from a design perspective Balloon should not need BalloonGenerator.

Suggestion on how to solve your problem:

  • Forward declare Balloon in BalloonGenerator

     your includes
     
 class ABalloon;
     
 your ABalloonGenerator

  • And in your spawn function in the generator set all the information the Balloon needs from the generator

     #include "Balloon.h" // include balloon in the cpp
 
 in the spawn function:
 
 auto* Balloon = GetWorld()->SpawnActor<ABalloon>(BalloonClassToSpawn, CreatePosition, Rotation, SpawnInfo);
 Balloon->Setup(all the information it needs to get)

That means only the BalloonGenerator.cpp needs to include the Balloon and you have no dependency from Balloon to the BalloonGenerator

3

Thanks, this is a good solution. I just got caught up in a tangent and wasn’t thinking what I was doing. Thanks for putting me back on track!