Kotlin Modules?

[Matt Helliwell]

Has anyone successfully got a module developed in Kotlin? I'm trying to write a Kotlin world generator(I have enough of Java a work!). The module builds ok but when run the game I get the error below.

I've played around adding Kotlin dependencies on the PC and Engine projects but without any joy. Has anyone any suggestions on the best way forward?

java.lang.NoClassDefFoundError: kotlin/jvm/internal/Intrinsics
at org.terasology.greatBritain.SurfaceProvider.process(SurfaceProvider.kt)
at org.terasology.world.generation.RegionImpl.lambda$getFacet$1(RegionImpl.java:49)
at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
at java.util.Iterator.forEachRemaining(Iterator.java:116)
at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
at org.terasology.world.generation.RegionImpl.getFacet(RegionImpl.java:48)
at org.terasology.logic.spawner.AbstractSpawner.findSpawnPosition(AbstractSpawner.java:51)
at org.terasology.logic.spawner.FixedSpawner.getSpawnPosition(FixedSpawner.java:49)
at org.terasology.world.generator.WorldGenerator.getSpawnPosition(WorldGenerator.java:49)
at org.terasology.logic.players.PlayerSystem.onConnect(PlayerSystem.java:151)
at org.terasology.logic.players.PlayerSystemMethodAccess.invoke(Unknown Source)
at org.terasology.entitySystem.event.internal.EventSystemImpl$ByteCodeEventHandlerInfo.invoke(EventSystemImpl.java:506)
at org.terasology.entitySystem.event.internal.EventSystemImpl.sendStandardEvent(EventSystemImpl.java:269)
at org.terasology.entitySystem.event.internal.EventSystemImpl.send(EventSystemImpl.java:260)
at org.terasology.entitySystem.entity.internal.BaseEntityRef.send(BaseEntityRef.java:145)
at org.terasology.network.internal.NetworkSystemImpl.connectClient(NetworkSystemImpl.java:831)
at org.terasology.network.internal.NetworkSystemImpl.joinLocal(NetworkSystemImpl.java01)
at org.terasology.engine.modes.loadProcesses.SetupLocalPlayer.step(SetupLocalPlayer.java:44)
at org.terasology.engine.modes.StateLoading.update(StateLoading.java:242)
at org.terasology.engine.TerasologyEngine.tick(TerasologyEngine.java:435)
at org.terasology.engine.TerasologyEngine.mainLoop(TerasologyEngine.java:400)
at org.terasology.engine.TerasologyEngine.run(TerasologyEngine.java76)
at org.terasology.engine.Terasology.main(Terasology.java:153)
Caused by: java.lang.ClassNotFoundException: Failed to find or load class kotlin.jvm.internal.Intrinsics
at org.terasology.module.sandbox.ModuleClassLoader.findClass(ModuleClassLoader.java:158)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at org.terasology.module.sandbox.ModuleClassLoader.loadClass(ModuleClassLoader.java:121)
at java.lang.ClassLoader.loadClass(ClassLoader.java57)
... 30 common frames omitted
Caused by: javassist.NotFoundException: kotlin.jvm.internal.Intrinsics
at javassist.ClassPool.get(ClassPool.java:452)
at org.terasology.module.sandbox.ModuleClassLoader$1.run(ModuleClassLoader.java:145)
at org.terasology.module.sandbox.ModuleClassLoader$1.run(ModuleClassLoader.java:142)
at java.security.AccessController.doPrivileged(Native Method)
at org.terasology.module.sandbox.ModuleClassLoader.findClass(ModuleClassLoader.java:142)

 

[Cervator]

So two potential things to investigate here:

1. Our engine's sandboxing will wall off anything not inside a module or on the whitelist, with the usual result being a NoClassDefFoundError - see https://github.com/MovingBlocks/Terasology/wiki/Modding-API for a bit of added detail. So probably you just need to add a few things like kotlin.jvm.internal.Intrinsics to the whitelist if that seems a fair thing to put on there
2. Kotlin and Scala modules have both been prototyped, but require subtly different build.gradle files to hook up the Kotlin or Scala. The two repos on GitHub should contain working versions - and you probably already have that in place since you got that far. I've got a newer build.gradle-less module approach working locally that simply sets the language via flag in module.txt but it breaks a bunch of other stuff.

 

[Matt Helliwell]

Thanks. I shall poke around a bit and see what I can come up with.

 

[Matt Helliwell]

I've got it going - I've added the package "kotlin.jvm.internal" to ExternalApiWhitelist#PACKAGES and added the Kotlin libs as a dependency to the engine project. That'll allow me to carry on prototyping my module. Once I've understood things a bit better I can create a pull request for the engine changes if no-one else beats me to it.