C++ "interface" classes and serialization

After some initial experimentation, I’ve made a few “interface” classes, which are operating as I expect them to. (I had a hard time finding reference material, but some answerhub searching turned up this, which was helpful).

I want my own interface classes to provide some mix-and-match style features to my AActor and APawn classes, and that part’s working fine. But it seems you cannot use a UPROPERTY in an interface class, so if I want the interface to hold any state of its own, I have to manage the serialization myself. I don’t want my interface class to be a first class AActor or even UObject, because class size is a concern.

Am I correct that I must manage the serialization myself for such classes? It’s not hard, but if there’s a better approach, I’d sooner avoid my own serialization if I can.

Also, is there any way to pass values into the constructors of interface classes, such as:

AMyPawn::AMyPawn() : IInterface_Whatever(4.0f, "hi", etc) { ... }

I tried this and the generated content tool became quite unhappy :).

Well, I can at least report that explicit serialization of interfaces (by overloading Serialize() in the base class and calling both its Serialize and the interface’s Serialize in turn) works okay.

I never got non-default constructors working for interfaces though - I’m guessing that isn’t possible, but as I’m new to the API, it’s possible I am just missing the way.