Anyway to include cpp header as plugin without compiling them into .dll?

Hi all, I am recently using Google Protobuf to feed data to my Unity3D project to update the game world. Firstly, I tried C# version of Protobuf, it works like a charm. However, the reality is my teammate is using cpp version of Protobuf/Protoc (and he uses it for some reason). In which case I can only get .h/.cc file in the run-time(or perhaps compile time, not quite sure, we gonna talk about it later). I have browsed the whole https://docs.unity3d.com/Manual/Plugins.html plugins page and it seems I have to compile my .h/.cc into .dll and add it into Unity3D project at compile time.

One solution is making a .dll in the run-time, honestly it is kinda hard to me.
Ideally, if I could write some C# scripts that can directly call the cpp function (with an "extern C" wrapper), that would be perfect. So I think my question is simple, is it possible to call cpp function without linking it as .dll?

 

The only supported method I'm aware of for adding c++ to Unity is via a dll plugin.

 

Thanks, the good news is that the .h/.cc can be generated at compile time. I think I need to compile the generated file into .dll by cmake options.