kotlinlang #reflect

test<Boolean>()

inline fun <reified T : Any> test() {
        when(T::class) {
            Boolean::class -> {}
            else -> throw NotImplementedError()
        }
    }

kirillrakhman

05/24/2017, 3:52 PM

you can do that without language features

kirillrakhman

05/24/2017, 3:53 PM

abstract class KnowsChildrenTypes() {
    companion object {
        val types = mutableSetOf<Class<out KnowsChildrenTypes>>()
    }
    
    init {
        types += this::class.java
    }
}

class Child1 : KnowsChildrenTypes()
class Child2 : KnowsChildrenTypes()

pniederw

05/24/2017, 11:59 PM

and converting to

Class

has undesirable side effects (e.g. kotlin.String -> java.lang.String)

deinspanjer

05/27/2017, 3:46 PM

So.. next issue.. I was going to try using the call

obj::class.simpleName

, and it said I needed to add the reflection jar to do that. I added it to my Maven Dependencies, but now, when I try to run, I get this error, even if I take out the ::class thing and leave my code just as it was when it runs without the reflection jar:

Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
Exception Details:
  Location:
    kotlin/reflect/jvm/internal/ReflectionFactoryImpl.function(Lkotlin/jvm/internal/FunctionReference;)Lkotlin/reflect/KFunction; @5: invokestatic
  Reason:
    Type 'kotlin/jvm/internal/FunctionReference' (current frame, stack[2]) is not assignable to 'kotlin/jvm/internal/CallableReference'
  Current Frame:
    bci: @5
    flags: { }
    locals: { 'kotlin/reflect/jvm/internal/ReflectionFactoryImpl', 'kotlin/jvm/internal/FunctionReference' }
    stack: { uninitialized 0, uninitialized 0, 'kotlin/jvm/internal/FunctionReference' }
  Bytecode:
    0x0000000: bb00 1059 2bb8 0042 2bb6 0020 2bb6 0021
    0x0000010: 2bb6 001f b700 38b0                    

	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:264)
	at kotlin.jvm.internal.Reflection.<clinit>(Reflection.java:32)
	at kotlin.io.ConsoleKt.<clinit>(Console.kt)
	at com.jsonlogic.RunnerKt.readInput(Runner.kt:40)
	at com.jsonlogic.RunnerKt.main(Runner.kt:14)

snowe

07/10/2017, 8:02 PM

Not sure if this was the best place to ask, but why is it not possible to accept a

java.util.List<? extends Blah>

type into a kotlin method that accepts a type of kotlins

kotlin.collections.List<out Blah>

dszopa

07/21/2017, 2:49 AM

Specifically when I debug I see that the java type shows up as

javaType!

indicating it could be nullable or non nullable, where as the kotlin type shows up as `kotlinType?`indicating nullable

mp911de

07/25/2017, 1:15 PM

Hi there. Is there some documentation on Kotlin’s synthetic constructor generation along with default arguments (bitmask used for defaulting)?

wouterdoeland

08/07/2017, 8:58 AM

Hi, how should I check whether a KType is equal to another KType? For example: I want to check whether a parameter in the constructor of an object is a String

grandstaish

08/26/2017, 2:15 AM

I'm trying to debug why Moshi doesn't work with Kotlin + ProGuard. The issue I'm seeing is that when ProGuard is enabled the call

rawType.kotlin.primaryConstructor

returns

null

. What sorts of things do I need to keep in order for kotlin-reflect to be able to find the primary constructor of a class at runtime? Just keeping the

@Metadata

annotation methods (as the library suggests) is not enough. Keeping all kotlin classes (

-keep class kotlin.** { *; }

) does work, but I'd rather just keep what I need.

janvladimirmostert

09/09/2017, 10:04 AM

I'm trying to invoke a function, but I 'm getting

java.lang.IllegalArgumentException: Callable expects 4 arguments, but 3 were provided.

This is the place where I'm doing the call:

annotation.listeners.forEach { listener: KClass<*> ->
					listener.functions.forEach { function: KFunction<*> ->
						if (function.name == "before") {
							function.call(annotation.action, request, response)
						}
					}
				}

And this is the method on the interface that's being called:

interface ControllerListener {
	fun before(action: String, request: RestRequest, response: RestResponse)
	fun after(action: String, request: RestRequest, response: RestResponse)
}

What should the fourth paramater be?

snowe

09/23/2017, 9:57 PM

If I have a property that I'm trying to add a modifier to it works fine, as long as there is no annotation on that property. Why is that? otherwise I get an exception

Marc Knaup

10/31/2017, 12:09 PM

I wonder why

.javaClass

doesn’t use

out

projection 😮

yoavst

11/10/2017, 10:20 AM

Can I improve this code without full reflection jar (for android)? I want to be able to pass only

boundReference::fieldName

miha-x64

11/19/2017, 11:15 AM

Any way to get actual type agruments from a reified type? E. g. in

someInlineFunc<A<X>, A<Y>, B<X>>()

, is there a way to say that first two type arguments are different? (Okay, I've resolved my task without it, now it's just a proof-of-concept question.)

snowe

11/20/2017, 8:28 PM

is there any way to declare functions programmatically with annotations on them?

sdeleuze

11/23/2017, 1:20 PM

I have found https://stackoverflow.com/a/33907581/1092077 from @udalov but slighly old response so maybe there is now a way to do that without using Jjava reflection ?

natpryce

11/24/2017, 3:10 PM

Hi. If I have a KClass<T>, how do I safely cast a value of type Any to a value of type T? I’m looking for a dynamic equivalent to the

as?

operator.

diesieben07

12/08/2017, 5:04 PM

I'm used to something like

getDeclaringClass

from Java.

kotlin.jvm.internal.CallableReference

has

getOwner

, but that is internal API and only available for references...

mp911de

01/17/2018, 4:21 PM

Hey there, is there a public API to discover the kind (

CLASS

FILE_FACADE

, …) of a Kotlin class?

beholder

01/18/2018, 5:35 PM

Is there analog of

Class.getEnclosingClass()

for

KClass

benny.huo

01/18/2018, 10:43 PM

Hey guys. I have a problem using kotlin-reflect with proguard. I called

superTypes

to retrieve superTypes of

RepoListFragment

while its superClass

CommonListFragment

was mapped to

com.bennyhuo.github.view.common.b

. The runtime crash:

java.lang.IllegalStateException: Incomplete hierarchy for class RepoListFragment, unresolved classes [com.bennyhuo.github.view.common.CommonListFragment]
at kotlin.reflect.jvm.internal.components.RuntimeErrorReporter.reportIncompleteHierarchy(RuntimeErrorReporter.kt:26)
at kotlin.reflect.jvm.internal.impl.serialization.deserialization.descriptors.DeserializedClassDescriptor$DeserializedClassTypeConstructor.computeSupertypes(DeserializedClassDescriptor.kt:187)

After hours of searching I found that kotlin-reflect get the type infomation from the annotation

Metadata

while the value of it may not be processed by proguard.

@Metadata(
   mv = {1, 1, 7},
   bv = {1, 0, 2},
   k = 1,
   d1 = {"..."},
   d2 = {"Lcom/bennyhuo/github/view/fragments/subfragments/RepoListFragment;", "Lcom/bennyhuo/github/view/common/CommonListFragment;", "Lcom/bennyhuo/github/network/entities/Repository;", "Lcom/bennyhuo/github/presenter/RepoListPresenter;", "()V", "adapter", "Lcom/bennyhuo/github/view/fragments/RepoListAdapter;", "getAdapter", "()Lcom/bennyhuo/github/view/fragments/RepoListAdapter;", "production sources for module app"}
)

Any suggestions or workaround?😳

albertgao

01/23/2018, 4:24 AM

I got a

param.type === nz.salect.objJSON.JVMBranchTest.MenuObject?

where

param:KParameter

. But when I tried to get the class definition from

param.type

via

param.type::class

. Instead of getting the above

MenuObject

, I get a

class kotlin.reflect.jvm.internal.KTypeImpl

. How to get my own class , I mean, a

KClass

? Thanks 🙂

albertgao

01/23/2018, 5:26 AM

How to check whether the type of objects inside a

List<*>

is a kotlin official class or my own class, I currently check its name:

paramName.substring(24).removeSuffix(">")

, so

"kotlin.collections.List<nz.salect.objJSON.Lesson>"

will become

"nz.salect.objJSON.Lesson"

, and then I can verify whether it

startsFrom("kotlin")

or not. What’s a better way to do this?

snowe

01/27/2018, 12:05 AM

yeah I didn't want to do that, wasn't sure if kotlin was capable of it. thanks!

groostav

02/02/2018, 1:29 AM

given a

KProperty1

instance, is it possible to know if its declaration is backed by a delegate?

Title

groostav

02/02/2018, 1:29 AM

given a

KProperty1

instance, is it possible to know if its declaration is backed by a delegate?

diesieben07

02/02/2018, 8:23 AM

There's a

getDelegate

function on

KProperty1

☝️ 1

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