Aspects

An aspect is the central organizational unit in AspectK. It is an object annotated with @Aspect that groups related advice methods.

Warning

Aspects must be declared as object, not class. Using class is not supported and will result in a compilation error.

Declaring an Aspect

import io.github.molelabs.aspectk.runtime.Aspect
import io.github.molelabs.aspectk.runtime.Before
import io.github.molelabs.aspectk.runtime.JoinPoint

@Aspect
object SecurityAspect {
    @Before(target = [RequiresAuth::class])
    fun checkAuthentication(joinPoint: JoinPoint) {
        val user = getCurrentUser()
            ?: throw UnauthorizedException("Not authenticated")
        println("Access granted to ${joinPoint.signature.methodName} for $user")
    }
}

Multiple Aspects

Multiple aspect objects can each provide advice for the same target annotation. AspectK applies all matching advice in the order aspects are discovered by the compiler.

@Aspect
object LoggingAspect {
    @Before(target = [Audited::class])
    fun log(jp: JoinPoint) { /* ... */ }
}

@Aspect
object AuditAspect {
    @Before(target = [Audited::class])
    fun audit(jp: JoinPoint) { /* ... */ }
}

@Audited
fun deleteUser(userId: String) { /* both log and audit run first */ }

Advice Order

The order of advice application across multiple aspect objects is determined by the compiler's IR traversal order and is not guaranteed to be stable across compiler versions. Design aspects to be order-independent when possible.

Aspect Discovery

AspectK's compiler plugin scans all IR files in the compilation unit for @Aspect-annotated objects. Only aspects defined within the same compilation classpath are discovered — aspects in external libraries are currently not supported.