Hi everyone, not sure if this was the right channe...

# reflect

[juancho]

Hi everyone, not sure if this was the right channel but I have a question regarding Kotlin Reflection. I posted the question in Stackoverflow:
https://stackoverflow.com/questions/53034830/kotlin-reflection-how-to-know-if-a-kotlin-class-is-marked-with-internal-modif
The question: I’m autogenerating code with KotlinPoet and Auto Service. I didn’t find any way to know if an annotated class has “internal” modifier so I can create another class with same modifier. For example:

@MyAnnotation
internal class Car

So I thought using Kotlin Reflection I would be able to get this information but no luck.

Any clues on how to do it?

[diesieben07]

Read the @Metadata annotation from whatever source you have for your kotlin class. Once you have that, you can use kotlinx-metadata-jvm (https://github.com/JetBrains/kotlin/tree/master/libraries/kotlinx-metadata/jvm) to parse this metadata. Where the metadata comes from does not matter. It can be from an annotation read at runtime or in an annotation processor.

[juancho]

Thanks man! It’s working!!! 👏

[juancho]

my only concern is how I’m parsing the metadata to create the KotlinClassHeader 🤔 . I’m manually parsing metadata to the params requested by KotlinClassHeader

[juancho]

values.forEach { value ->
                when(value.fst.name.toString()) {
                    "mv" -> metadataVersion = (value.snd.value as List<Attribute.Constant>).map { it.value.toString().toInt() }.toIntArray()
                    "bv" -> bytecodeVersion = (value.snd.value as List<Attribute.Constant>).map { it.value.toString().toInt() }.toIntArray()
                    "k" -> kind = value.snd.value.toString().toInt()
                    "d1" -> data1 = (value.snd.value as List<Attribute.Constant>).map { it.value.toString() }.toTypedArray()
                    "d2" -> data2 = (value.snd.value as List<Attribute.Constant>).map { it.value.toString() }.toTypedArray()
                }
            }

[juancho]

Do you know if there is an easy way to do that?

[diesieben07]

I am not sure what API you are using, but it does not seem to be the javax.lang.model one. AnnotationMirror gives you a map of annotation values, where each one is an AnnotationValue instance with a getValue method. That one would return a List<Int> for an int array, for example.

[juancho]

looks like is the same that I’m using but accessed from this other API annotationMirrors. Unfortunately it returns a List<Attribute$Constant> so I have to map this to a List<Int>, like I’m doing in the code above

[diesieben07]

I am not sure what that API is. Do you have docs for it?

[juancho]

I’m using Auto Service: https://github.com/google/auto/tree/master/service

[juancho]

and this is what I see:

[juancho]

image.png

[juancho]

and for annotationMirrors is the same:

[juancho]

image.png

[juancho]

and className is:

override fun process(annotations: MutableSet<out TypeElement>, roundEnv: RoundEnvironment): Boolean {
        roundEnv.getElementsAnnotatedWith(AutoDsl::class.java).forEach { classElement ->

[diesieben07]

Don't get distracted by the debugger stuff. Look at the Javadocs, here is AnnotationMirror, for example: https://docs.oracle.com/javase/10/docs/api/javax/lang/model/element/AnnotationMirror.html

[diesieben07]

It has a quite straightforward API.

[juancho]

Thanks @diesieben07 I’ll give it a try!