experiment and document how-to on prefab package

[atsushieno]

As of filing this issue, prefab package already builds and pushed as build artifact, but it is totally untested. Since it is not really doable to reference local aar, I still haven't really added it to our androidaudioplugin-lv2 build.gradle.

[atsushieno]

After reading https://github.com/google/prefab/issues/97 prefab does not seem to be a viable solution. What we need is some solution that makes sense:

• We can build androidaudioplugin.aar that contains both include and libs and Kotlin API/implementation, not apart.
• We can reference it just as a dependency (implementation project(':androidaudioplugin')) in androidaudioplugin-lv2. AGP should automatically add includes as well as libs.
  • prefab module description makes sense here if we need to specifically add references e.g. if things are ABI-specific.

Without such integration (like what Xamarin.Android does), it is not quite useful.

What could be workarounds until we develop some Prefab alternative?

• Add paths to build/intermediates/merged_native_libs/debug/out/lib/ - it is the current solution. It's just horrible.
• split native parts from Kotlin implementation - so, if a user wants to reference androidaudioplugin.aar then user will have to add another reference to, say, androidaudioplugin-prefab.aar ? Needs actual experiment.

[atsushieno]

Since it is not really doable to reference local aar

It does not seem to be true nowadays - https://stackoverflow.com/a/51640593/1465645

[atsushieno]

The StackOverflow solution above didn't work.

[alexcohn]

See https://github.com/alexcohn/ndk-samples/tree/prefab/unified-aar/prefab/hello-libs

This example does exactly this: an AAR that is both a Prefab and Java dependency.

[atsushieno]

Nice, thanks for the heads up. I visited the same prefab directory in the original android-ndk tree and found that there is now a new prefab build property (or whatever describes it) in build.gradle, so the latest AGP seems to have the corresponding task that makes sense. https://github.com/android/ndk-samples/blob/1fa89b10613a670520f7a9dee9a6980f5d90f0f8/prefab/prefab-publishing/mylibrary/build.gradle#L46 That's a game changer.