Hello all. I have a question that Google has not b...

# kotlin-native

[brandonlamb]

Hello all. I have a question that Google has not been able to help me with.

Does K/N currently support C -> Kotlin interop? If so, any documentation? If not, is this a planned/roadmap feature?

I'm trying to integrate Kotlin Native with the Godot game engine, I have a dynlib compiling but I'm realizing I dont know how to expose a godot_gdnative_init() function for the game engine to find and call.

[dany]

https://github.com/JetBrains/kotlin-native/blob/master/INTEROP.md ?

[dany]

or maybe you mean the other way around?

[brandonlamb]

https://blog.jetbrains.com/kotlin/2017/12/kotlinnative-v0-5-released-calling-kotlin-from-swift-and-c-llvm-5-and-more/

Just came across this, looks like it is supported but I'm not seeing docs/examples yet.

Yes I mean the other way around, C calling into a Kotlin Native code/library

[brandonlamb]

https://github.com/godot-addons/godot-kotlin

So far I have code that does the cinterop against the C API for godot engine, and trying to expose the two functions that godot needs godot_gdnative_init() and godot_gdnative_terminate(). I get a dynlib compiled, and when I try to load this, godot says it cant find the function.

I'm assuming that I'm missing a step, or annotation, or something

[dany]

never used it but isnt it possible with a dynamic lib?
https://github.com/JetBrains/kotlin-native/blob/master/GRADLE_PLUGIN.md#building-dynamic-libraries-and-frameworks

[svyatoslav.scherbina]

We have a sample for this feature with dynamic libs:
https://github.com/JetBrains/kotlin-native/tree/master/samples/python_extension
To expose a function under predictable name you can use @konan.internal.CName annotation:

@konan.internal.CName("godot_gdnative_init")
fun godot_gdnative_init(o: CPointer<godot_gdnative_init_options>>?) {
}

(or something like this).

[svyatoslav.scherbina]

Also if you only need to expose a couple of functions, you have an option to compile to program instead of dynamic library, but expose the function with @konan.internal.ExportForCppRuntime. However this annotation is more internal 🙂