Hi everyone, I'm currently trying to develop a Gradle Plugin that will generate Kotlin Code. I'm struggling with properly setting up the source sets and output directory. While this is a plugin for Kotlin in general, it should also work for Android. So far I got this:

class MyPlugin : Plugin<Project> {
  override fun apply(project: Project) {
    val myPlugin = project.extensions.create("myPlugin", MyPluginExtension::class.java)
    val kotlin = project.extensions.getByType(KotlinProjectExtension::class.java)
	
	kotlin.sourceSets.forEach { sourceSet ->
	  val destination = project.layout.buildDirectory.dir("generated/myPlugin/${sourceSet.name}") // TODO: this feels wrong
	  sourceSet.kotlin.srcDir(destination)
	  project.tasks.register(
	    "generateMyCode${sourceSet.name}", // TODO: this feels wrong
		GenerateCodeTask::class.java
	  ) {
	    it.destination.set(destination)
	  }
	}
  }
}

The source set does get detected but registering all the tasks doesn't feel right. I thought of this because in Android you get all those tasks for each build variant, but like this many more tasks are registered (e.g. for *AndroidTest) Follow up question: what's the correct way to attach this to e.g. the assemble task?

The

assemble

task should not get these attached. And you should not register the plain directory as source dir. You should instead make sure that the

GenerateCodeTask

task properly declare its inputs and outputs as always, and then set the instances of this task as

srcDir

this will then automatically add task dependencies where needed automatically, so that every consumer of source files - be it a compile task, as static code analysis task, a sources jar task, ... - automatically gets the necessary task dependency and sees all sources. At least that's how it works with "normal" projects. Not sure how to do it properly for Android as Android is always special and I'm not into android development. 🙂

Thanks for the quick reply! My task looks somewhat like this:

class GenerateMyCodeTask : DefaultTask() {
 @get:OutputDirectory val destination: DirectoryProperty = project.objects.directoryProperty() 
}

And I changed the plugin to

val task = project.tasks.register(...) { it.destination.set(destination) }
sourceSet.kotlin.srcDir(task.get().outputs)

Is that the intended way?

Even

sourceSet.kotlin.srcDir(task)

should do if you do not have other outputs in it. If you do, using

get()

is bad as you break task-configuration avoidance, but should use

flatMap

in that case.

You can also have a single code generating task and wire its output to the

main

(or

commonMain

) Kotlin source set

Thanks @Vampire, that works too!

You probably need only one of those lines in each block. 👍

Yeah, Slack does weird things...

Besides that, I prefer detecting if AGP is applied using

pluginManager.withId("com.android.library"), ....

instead of a big try/catch but I guess the try/catch should work too

Thanks for all that info! Haven't come across that GitHub repo yet for some reason. I'll look into it and the Apollo plugin too. I'm certain I'll find a good setup with all that 🙏

@Fredrick Eisele was that supposed to land in that thread?

Nope, wrong place.