This prototype acts as a 'Proof of Concept' and is not yet endorsed by JetBrains or Kotlin by any means.
Java's ServiceLoader is a pretty popular implementation of a generic 'Service Provider Interface.' This ServiceLoader (and similar mechanisms), however, have the following problems:
- They do not support Kotlin/Native
- Reflection or IO at runtime might be undesirable for some applications
- Reflection might be unsafe
This spi implementation, whilst also being multiplatform, is fully static. All services will be known at compile time; The corresponding IR or ByteCode will be generated to link them.
Note: This does not mean that the services have to be visible to the currently compiled module. Each 'execution' gets associated with their own 'spi compilation' and will be provided the module at runtime.
Code gets compiled against the kotlinx.spi.runtime module which, by default, returns an empty sequence
of services. However, when the kotlinx.spi plugin is applied to a project, then each 'executable'
will get assigned its own compilation of a real kotlinx.spi.runtime.
e.g. when running jvmRun, this execution will have its associated compilation :compileKotlinSpiJvmMain
which will look at the runtime classpath and generated the necessary links.
The Kotlin/Native implementation requires one additional change to the KotlinLibraryResolver in order
to replace the kotlinx.spi.runtime module with a 'real' one. See the commit in kotlin/sellmair/spi.
This kotlinx.spi implementation requires a small change in the Kotlin/Native compiler which can be found in the
sellmair/spi branch of Kotlin. The K/N compiler needs to be built first and provided in the
gradle.properties file.
Run jvm/main
cd playground
./gradlew :app:jvmRun -DmainClass=MainKtRun jvm/test
cd playground
./gradlew :app:jvmTest --rerun -iRun macosArm64/main
cd playground
./gradlew :app:macosRun