is it possible to define reified generic types in an interface or will i have to pass in the type as a second parameter? simple example that i'm playing around with:

interface JsonProvider {
	fun <T> fromJson(input: String): T
	fun <T> fromJsonList(input: String): List<T>
}

Gson for example now requires the class type to be passed in:

class Blah : JsonProvider {

	val gson = com.google.gson.Gson()

	override fun <T> fromJson(input: String): T {
		return gson.fromJson(input, T::class.java)
	}

unless that

T

is reified and fromJson / fromJsonList are inlined, IntelliJ complains and reifying that T inside the interface doesn't seem to be supported.

Listened to an awesome talk by @kevinmost today at Øredev, about idiomatic Interop with Kotlin. He also said he’s going to create a compiler plugin which will create builders for kotlin classes to allow usage from Java. Is it finished yet Kevin? :)

A question related to reflection and `data class`’s copy method. Currently I am have something like this

enum class GeneralModifier {
    Less, Normal
}

data class Latte(
    val ice: GeneralModifier = GeneralModifier.Normal,
    val milk: GeneralModifier = GeneralModifier.Normal
) : Coffee()

And the selection input is

Pair<String, Enum<GeneralModifier>>

, where the first one is the field name, e.g. “ice” So I do

tem.copy(
  ice = if (field == "ice") GeneralModifier.values().first { it == option } else item.ice,
  milk = if (field == "milk") GeneralModifier.values().first { it == option } else item.milk
)

Is there a easier way to do the

copy

?

I would have expected the inliner to just copy the code as is and file in all the type parameters with the real type variable

Hi! Still learning functional things in Kotlin and I'm not sure if solution is done optimal. Can someone please check my example and tell me if this can be done better? https://try.kotlinlang.org/#/UserProjects/h9ra2isjl4vudcq3mmo8gii4n8/fb6lvfgtq7ppf3es5tt36b5h0o Thanks!

Is there a way to globally enable contracts in Kotlin 1.3? Per module or even throughout the entire project. It's a little tedious to add the

@ExperimentalContracts

annotation absolutely everywhere. Thanks! :D Not entirely sure where to ask for this. If it's suitable for another channel, I'd be happy to move the question over there.

Can I declare an enum class that has the same name as one of its members in Kotlin. Example:

enum class Potato(val a : Int) {
     Potato(3);
}

This is possible in Java but it seems like it's not allowed in Kotlin?

hi, is Any::class.java equivalent in Kotlin to Object.class from Java?

Hmm, Kotlin (on the JVM in this case) defines some new exceptions and also aliases some of Java's exceptions (like

kotlin.RuntimeException

is actually just a typealias for

java.lang.RuntimeException

). And all of Kotlin's own exceptions will ultimately inherit from

kotlin.Throwable

, whereas Java's exceptions will inherit from

java.lang.Throwable

). But does that mean that catching

kotlin.Throwable

only won't actually catch e.g. `java.lang.RuntimeException`s?

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I am looking at docs and see this. Why wouldn't

isEmpty

be a function? Also wouldn't the value stored in

isEmpty

never be referenced?

also another (probably dumb) question. "Fields cannot be declared directly in Kotlin classes." umm... they can? I am confused

is there a cheap way to deserialise a data class to a String and serialise it back from a String

Hey small question about this PR https://github.com/JetBrains/kotlin/pull/1994. I see it has been merged however I don’t see this commit on the list of commits on

master

branch here https://github.com/JetBrains/kotlin/commits/master. Am I looking at incorrect branch 🤔

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I am taking code which makes the most sense in a linear fashion and inputting it into an executor which is iterative. This seems to call for a

sequence{}

... except I wouldn't return anything and just execute... (so if I used 'yield' I would have to return meaningless values). Is there a better way to implement this?

I updated IDEA to 2018.3 now I can't use Kotlin because I get Incompatible with the current IntelliJ IDEA version Please what can I do to resolve?

Hi there! Currently I need a little advice on kotlin, mutable/readonly collections and MongoDB mappings. My current minimal setup is for example

import org.springframework.boot.ApplicationRunner
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
import org.springframework.context.annotation.Bean
import org.springframework.data.annotation.Transient
import org.springframework.data.mongodb.core.mapping.Field
import org.springframework.data.repository.reactive.ReactiveCrudRepository
import org.springframework.stereotype.Repository
import reactor.core.publisher.Flux
import java.util.*

class Test(
        list: List<String>,
        val id: UUID = UUID.randomUUID()
) {

    @Field("list")
    private val _mutableList: MutableList<String> = list.toMutableList()

    val list: List<String>
        @Transient get() = _mutableList
}

@Repository
interface TestRepository : ReactiveCrudRepository<Test, UUID>

@SpringBootApplication
class DemoMongoMappingApplication {

    @Bean
    fun runner(testRepository: TestRepository) = ApplicationRunner {_ ->
        Flux.just("a", "b", "c")
                .map { Test(listOf(it)) }
                .collectList()
                .flatMapMany { testRepository.saveAll(it) }
                .flatMap { testRepository.findById(it.id) }
                .subscribe { println("Found $it.id") }
    }
}

fun main(args: Array<String>) {
    runApplication<DemoMongoMappingApplication>(*args)
}

Sadly this fails during load of my entities with

org.springframework.data.mapping.MappingException: No property list found on entity class com.example.demomongomapping.Test to bind constructor parameter to!

. The problem seems to be with the backing property

_list

. Any suggestions how you solve those issues?

Is this expected behaviour? If so, can someone explain why?

Why is there no package visibility modifier in kotlln? For example, I have a package for my DB access in my server. I want to only expose one class to the rest of the app to avoid confusion. In the package I also have several repositorieclasses for each of my enteties, I do not want for example the controllers package to access those repositories directly, I want it instead to go through my master

DB

class. How can I do that in kotlin?

Does anyone know if there's a solution to kotlin + JaCoCo? I cannot meet my quality gates in sonar because coverage is too low. There are a couple of functions that should be covered though

Any chance of a date/time feature set appearing in the standard library? It’d be pretty useful for multiplatform

I'm writing a cross-platform (jvm + native) library, a Kotlin date/time library or feature set would help immensely.

Does the for/in loop use iterator() underneath?

so there is no point of doing: list.iterator().forEach instead of: list.forEach

I am looking for a static analysis tool that given a className prints to the console its Type Hierarchy in my project. Example

$ ./staticAnalysis android.app.Activity
android.app.Activity
  \-- FragmentActivity
    \-- AppCompatActivity
         \-- MyActivity1
         \-- MyActivity2

Does that exist?

Android project:

Koin

or

Kodein

and why?

kind of an academic, please-don’t-think-I’m-actually-using-this sorta question - is there any sort of provision to have two methods with the same name and signature, but with one having a type parameter (specifically

reified

vs no type param, (thanks for clarifying @halley))? the compiler complains about a platform declaration clash, which I suppose makes sense since there’s no real overloading happening there, but since the second method has to be

inline

anyhow, could the compiler not figure out what you mean at compile time and inline the appropriate method to avoid the signature clash?

Anyone here use GitKraken on Windows?