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FAQ

General

What is the difference between AspectK and AspectJ?

AspectK is annotation-driven and works exclusively through the Kotlin K2 compiler IR API. It supports Kotlin Multiplatform (JVM, JS, WASM, Native), while AspectJ only targets JVM. AspectJ offers richer pointcut expressions; AspectK uses simpler annotation-based targeting.

Does AspectK support @After or @Around advice?

Currently, only @Before is supported. @After and @Around advice are planned for future releases.

Can I use AspectK with Kotlin versions other than 2.2.x?

No. AspectK targets the K2 IR transformation API and is tested against the 2.2.x series only. Using a different Kotlin version may cause compilation errors due to K2 IR API changes.

Setup

Why isn't my aspect being applied?

Check the following:

  1. Plugin is applied: Ensure id("io.github.mole-labs.aspectk.compiler") is in your plugins {} block.
  2. Runtime dependency: aspectk-runtime must be on your compile classpath.
  3. Aspect in same compilation unit: AspectK only discovers aspects compiled in the same unit. Aspects from external JARs are not currently supported.
  4. Advice signature: The advice method must accept exactly one JoinPoint parameter and return Unit.

Does the order of advice execution matter?

Advice is applied in the order aspects are discovered during IR traversal. This order is not guaranteed across compiler versions. Design your aspects to be order-independent.

Runtime Behavior

What is JoinPoint.target for extension functions?

For extension functions, target is the receiver of the extension, i.e., the this object inside the extension function body.

Why does MethodSignature.returnType show Any for a generic function?

Generic type parameters are erased at compile time. For a function fun <T> box(value: T): T, the returnType is Any::class (the upper bound of the unconstrained type parameter T). Use returnTypeName if you need the source-level type name.

Are annotation default values available in AnnotationInfo.args?

No. Only arguments explicitly provided at the annotation use site appear in args. Default values are not captured.

Contributing

How do I add a new advice type?

See the Contributing guide for the IR transformation pipeline and how to add new advice injection strategies.