How can you use macros in Kotlin

Question

jw · Answer

Define an inline function that calls the macro in C and then call that function from Kotlin

jw · Answer

hfhbd · Answer

Yeah I try it <https kotlinlang org docs native c interop html macros> ``` static inline int jniExport return JNIEXPORT static inline int jniCall return JNICALL ``` I just want to create a JNI function `JNIEXPORT int JNICALL Java Main hello JNIEnv env jobject obj jstring from jint repeat `

hfhbd · Answer

Wow it works without the macros

Landry Norris · Answer

JNIExport just adds an attribute telling the compiler not to obfuscate or otherwise modify the symbol name If you don t need this it s optional but could fail in hard to debug ways

Landry Norris · Answer

``` attribute visibility default ```

hfhbd · Answer

Thanks Maybe this is fixed by using ` CName Java Main hello ` At least using the release build works <https github com hfhbd kotlinJni>

Landry Norris · Answer

I don t think Kotlin supports C attributes on functions in any meaningful way For what it s worth I moved an Android NDK C library to Kotlin Native for work and we ve been using it in production without issues for a month now

Landry Norris · Answer

Yeah The CName annotation is a good idea I m not using `RegisterNatives` right now so I have to use CName anyway to match the symbol name the JVM expects

hfhbd · Answer

That s sound promising smile

hfhbd · Answer

Do you also know what JNICALL is

Landry Norris · Answer

Not sure

Landry Norris · Answer

Just out of curiosity are you working on this for Android or desktop

hfhbd · Answer

Mainframe smile

Landry Norris · Answer

Cool I ve been working on writing a library for JNI bindings in Kotlin lately I ve been working with Android only so far I need to do more with the server and desktop space using JNI

hfhbd · Answer

I was surprised about lack of good documentation how to write a native android lib app with Kotlin native

Landry Norris · Answer

I agree It seems like the NDK doesn t get the same level of support the last maven central scan found 24 libraries for ndk It s disappointing because I feel like Kotlin could be a very good replacement for C++ on the NDK

Landry Norris · Answer

I think the big limitation right now is the lack of unit testing support on the ndk I usually have to set up a linuxX64 target since it s the closest if I want unit tests to work and just run tests there and hope that it works on the ndk if it works on linuxX64

natario1 · Answer

It s been a while now since last update but I wrote a gradle plugin for `androidNative` testing <https github com deepmedia multiplatform testing> It downloads and configures an emulator that can run your architecture builds a test executable and runs it