9_annotations.kt

import kotlin.reflect.full.*    // required import

annotation class ImAPlant

@Target(AnnotationTarget.PROPERTY_GETTER)
annotation class OnGet
@Target(AnnotationTarget.PROPERTY_SETTER)
annotation class OnSet

@ImAPlant class Plant {
    fun trim(){}
    fun fertilize(){}

    @get:OnGet
    val isGrowing: Boolean = true

    @set:OnSet
    var needsFood: Boolean = false
}

//::class to get information about a class at runtime. 
//declaredMemberFunctions to get a list of the methods of a class. 
fun testAnnotations() {
    val classObj = Plant::class
    for (m in classObj.declaredMemberFunctions) {
        println(m.name)
    }

    val plantObject = Plant::class
    for (a in plantObject.annotations) {
        println(a.annotationClass.simpleName)
    }

    val myAnnotationObject = plantObject.findAnnotation<ImAPlant>()
    println(myAnnotationObject)
}

fun main() {
    testAnnotations()
}