Is there any way that I can guarantuee/force that a class and its companion object(s) have been initialized when I want to do something with a

KClass<SomeLibraryType>

? It looks like the companion objects are only initialized lazily when the first instance of that class is created. For a custom typesystem in K/N I need to access the companion object of a given

KClass<SomeLibraryType>

received through an inline reified fun so I can lookup some type information and casting functions.

I am creating a library by interoping with an objc framework. When using a class that generates Kotlin symbols like below, the constructor returns null and no value is placed in the error pointer, causing a kotlin.NullPointerException. I would like to retrieve the contents of NSError by having a value in the error pointer. Is there any way to do this?

generated interop symbol
@ExternalObjCClass public open class SomeObjCClass : NSObject {
  @ObjCConstructor public constructor(arg: String, error: CPointer<ObjCObjectVar<NSError?>>?) { /* compiled code */ }
  @ObjCConstructor public constructor() { /* compiled code */ }
  @Deprecated @ObjCMethod @ConsumesReceiver @ReturnsRetained public open external fun init(): SomeObjCClass? { /* compiled code */ }
  @Deprecated @ObjCMethod @ConsumesReceiver @ReturnsRetained public open external fun initArg(arg: String, error: CPointer<ObjCObjectVar<NSError?>>?): SomeObjCClass? { /* compiled code */ }
}

objc　header
@interface SomeObjCClass : NSObject
- (instancetype)init NS_UNAVAILABLE;
- (nullable instancetype)initWithArg:(NSString *)arg error:(NSError **)error;
@end

Hello, I am working on a project that is using a prebuilt static .so file and generated .h with cinterop in kotlin-native. Currently the project will build and compile just fine when none of the methods from the .so file are reference. Once I reference the functions from the .so and attempt to compile my code I am getting a linking error on both linux and macos. The error occurs in the linkDebugExecutableNative step and the error reads out

Undefined symbols for architecture x86_64 '_askar_version', referenced from _askar_askar_version_wrapper76 in result.o ld symbol(s) not found for archutecture x86_64

From what I understand the linker cannot find the definitions for the package for the target platform and is most likely looking in the standard include folders throughout the system but because it is a custom package they are not located there. Any advice on how to fix this would be greatly appreciated or if this is even something supported by cinterop.

Does anyone have any experience setting up GitHub Actions for Kotlin native to support building the different Konan targets from https://kotlinlang.org/docs/native-target-support.html? So far, I have

linuxX64

,

macosX64

, and

mingwX64

figured out, and have a

konan-target

and associated

os

matrix parameter for those. Note: I just need the GitHub Action script settings, I know how to pass that to the build script.

Is any documentation available somewhere on implementing a "platform"

MAIN

dispatcher for kotlinx.coroutines on Kotlin Native?

With kotlin native how do I include a created cinterop library with the final executable. Currently when I try to run the executable generated from my project it is looking for the .so file the corresponds to the library that I used the cinterop tool on, I would rather that this gets built into the final executable so that the end user does not have to install this dependency along with the project. I have already tried to use the staticLibrary option in the .def file

I’m calling a cinterop-generated function that requires a callback as an argument. I’m using

staticCFunction()

to pass in a custom callback, but the callback requires some boilerplate to handle the C types. Is it possible to ‘wrap’ this callback with one of my own, without breaking the ‘no references’ rule for

staticCFunction()

? What I want is something like this, but this fails because “kotlinx.cinterop.staticCFunction must take an unbound, non-capturing function or lambda, but captures at (…) callback”

fun main() {
  attachAudioMixedProcessor { samples, frames ->
    for (frame in 0 until frames.convert()) {
      val left = samples[frame * 2 + 0]
      val right = samples[frame * 2 + 1]

      // ...
    }
  }
}

fun attachAudioMixedProcessor(
  callback: (samples: CPointer<FloatVar>, frames: Int) -> Unit
) {
  // call the c-interop function
  AttachAudioMixedProcessor(staticCFunction { buffer: COpaquePointer?, frames: UInt ->
    val samples: CPointer<FloatVar> = buffer?.reinterpret() ?: return@staticCFunction
    callback(samples, frames.toInt())
  })
}

// generated C interop function
external fun AttachAudioMixedProcessor(processor: CPointer<CFunction<(COpaquePointer?, UInt) -> Unit>>?)

I just watched and it seems backwards to me. Wouldn't you want this to fail at compile time so that it doesn't fail at runtime? I haven't worked much with K/N so maybe I'm missing something.

Is store data of login in the room database a good idea? What I have to do for storing data securely in app. I need some light on this point...

Is the following scenario unsupported? I have • An

external.so

shared library • A

base

kotlin module with cinterop bindings to

baseHeader.h

(external.so) • A

derived

kotlin module with cinterop bindings to

derivedHeader.h

(external.so). This module depends on the

base

module. What happens is that

derived:commonizeCInterop

fails:

Unresolved classifier: some/symbol/from/baseHeader.h

Is there a way to use kotlin native and multiplatform to write the common code as kotlin native?

I’m wondering if anybody could give some pointers (pun unintended) 😛 on how to resolve an issue I’m facing with cinterop in a multi-platform project I’m building? Here are some of the details. • Project is located https://github.com/CoreyKaylor/kotlin-lmdb • The project depends on native compiled lmdb key-value store • There is a commonMain, jvmMain, nativeMain initially created from the IntelliJ new project dialog. • There are tests located in commonTest that cover both jvm and native. • jvm is using jnr-ffi package for the interop and all tests are passing at this point here • native tests are flakey and fail roughly 80% of the time • I believe it’s possible the cause is the initial creation of the Env class that passes a double pointer to the native mdb_env_create function • The failure actually occurs in the mdb_env_open function, but that depends on the outcome from the create function • That said, it passes sometimes so I’m confused. Here is a snippet of the env creation code, but again I’m not sure the problem even lies here.

import kotlinx.cinterop.*
import lmdb.*

actual class Env : AutoCloseable {
    private val envPtr: CPointerVar<MDB_env> = memScoped { allocPointerTo() }
    internal val ptr: CPointer<MDB_env>

    init {
        check(mdb_env_create(envPtr.ptr))
        ptr = envPtr.value!!
    }

    private var isOpened = false

    actual var maxDatabases: UInt = 0u
        set(value) {
            check(mdb_env_set_maxdbs(ptr, value))
            field = value
        }

    actual var mapSize: ULong = 1024UL * 1024UL * 50UL
        set(value) {
            check(mdb_env_set_mapsize(ptr, value))
            field = value
        }

    actual var maxReaders: UInt = 0u
        set(value) {
            check(mdb_env_set_maxreaders(ptr, value))
            field = value
        }

    actual val stat: Stat?
        get() {
        val statPtr: CValue<MDB_stat> = cValue<MDB_stat>()
        check(mdb_env_stat(ptr, statPtr))
        val pointed = memScoped {
            statPtr.ptr.pointed
        }
        return Stat(
            pointed.ms_branch_pages, pointed.ms_depth, pointed.ms_entries, pointed.ms_leaf_pages,
            pointed.ms_overflow_pages, pointed.ms_psize
        )
    }

    actual val info: EnvInfo?
        get() {
            val envInfo: CValue<MDB_envinfo> = cValue<MDB_envinfo>()
            check(mdb_env_info(ptr, envInfo))
            val pointed = memScoped {
                envInfo.ptr.pointed
            }
            return EnvInfo(pointed.me_last_pgno, pointed.me_last_txnid,
                pointed.me_mapaddr.toLong().toULong(), pointed.me_mapsize, pointed.me_maxreaders, pointed.me_numreaders)
        }

    actual fun open(path: String, vararg options: EnvOption, mode: UShort) {
        check(mdb_env_open(ptr, path, options.asIterable().toFlags(), mode))
        isOpened = true
    }

    actual fun beginTxn(vararg options: TxnOption) : Txn {
        return Txn(this, *options)
    }

    actual fun copyTo(path: String, compact: Boolean) {
        val flags = if (compact) {
            0x01u
        } else {
            0u
        }
        check(mdb_env_copy2(ptr, path, flags))
    }

    actual fun sync(force: Boolean) {
        val forceInt = if(force) 1 else 0
        check(mdb_env_sync(ptr, forceInt))
    }

    actual override fun close() {
        if (!isOpened)
            return
        mdb_env_close(ptr)
    }
}

What's the best way to declare a dependency on an external library in Kotlin/Native?

This video from KotlinConf is really cool and funny, you won't regret watching it. It's about hacking video games using Kotlin/Native by @Ignat Beresnev ❤️👏

I’m trying to create some bindings for Jolt Physics (by way of zphysics). I’ve generated the K/N cinterop, but I’m having trouble converting some C code to Kotlin. I’ve tried it a few different ways, but when I run my K/N app it just crashes, with no error. Is there a way to get more information about runtime errors? Here’s the C code I’m trying to convert. It fails on

JPC_BodyInterface_CreateBody

JPC_Body *floor = JPC_BodyInterface_CreateBody(body_interface, &floor_settings);

my Kotlin code is in the thread 🧵 I guess it’s a problem with passing in the

floor_settings

pointer? Or maybe

body_interface

isn’t stable? Do I need to pin it?

Is there anyway to stack allocate in kotlin native, specifically not value classes as thats just optimization. I’m guessing its not possible with data classes etc, but is there a way with some very unsafe code. Like allocating directly into a buffer each primitive at specific addresses

I'm guessing the Win32 Core Audio APIs aren't included in the K/N win32 bindings?

How can I pass an action to UiKit Button using Kotlin/Native: when I used staticCFunction, I get this error:

kotlinx.cinterop.staticCFunction must take an unbound, non-capturing function or lambda, but captures at:

Also using

sel_registerName

the crashes when I click the button

button.addTarget(

target = _this_,

action = sel_registerName("action"),

forControlEvents = UIControlEventTouchUpInside

)

For anyone interested I worked on Fly.io distributed systems challenges in kotlin native here. The repo has solutions up until the Grow-Only Counter and the impl models stdin stdout stderr as flows using a mixture of atomics and actors.

Is there any timeline when the old MM will be removed?

https://kotlinlang.slack.com/archives/C3PQML5NU/p1683311195718599 Cross-posting in hopes that someone here might have an answer.

Hello, why the

frame

property from

UIView

in iOS is exposed as a

val

, and not as a

var

like in Swift and Objective-C? This is a big blocker for something I want to achieve 😕

Are KN binaries statically linked by default? Or is it standard practice to provide linkerOptions in the gradle DSL? I tried to run a binary in a scratch container but it was no bueno 😞

Hi folks! There anyway of using HiddenFromObjc annotation in a public class/objects? First of all, I’m looking to create a compiler plugin that annotated Kotlinx.serialization serializer with HiddenFromObj to be able use the serializers only on KMM source code and not export the KtxSerialization at the Native Headers.

Hi, can you help with this https://kotlinlang.slack.com/archives/C3PQML5NU/p1683808505136869 ?

I noticed the latest 1.9.0-Beta-104 includes this commit, which adds

@ExperimentalForeignApi

to Kotlin/Native kotlinx.cinterop APIs, like

CPointer

,

memScoped

,

alloc

,

convert

, as well as most C/ObjC interop generated APIs. Could someone please explain this change? Are apps that use C interop expected to opt in to this annotation globally?

After struggling for a week to get a cross compilation environment setup for my Kotlin Native io uring project I finally got something very cool working. I brain dumped everything into a blog post this evening, so it’s likely a little less refined than my usual content. Theres tons cool things covered including: Remote development inside a container from Intelli J, Docker build time volumes and more!

Are we going to have interop with native Swift modules ? You mentioned that in KotlinConf I want to know how close we are to achieve this

I write a simple kmm demo, the code is quite simple: klib contents`package com.example.kmmappdemo {` class Fibonacci constructor() { fun calc(num: Long): Long } class Greeting constructor() { fun greet(): String } class IOSPlatform constructor() : Platform { override val name: String } interface Platform { val name: String } } package com.example.kmmappdemo { fun getPlatform(): Platform } The klib is only 8KB, however, the shared.framework/shared is too big: 837KB It seems that kotlib stdlib and garbage collections is also compiled into the dynamic framework. My question is, is it possible for me to split the klib generated framework into two parts, the default one and the customized one, like how it's managed in flutter. In Flutter, there are two frameworks, Flutter.framework and App.framework. Flutter.framework includes the stdlib and garbage collections parts, the app.framework is the business code written by developers.

Hey there, anybody know if cinterops can be used with a dynamic library instead of a static one ?