kotlinlang #announcements

I am using experimental multiplatform features from Kotlin 1.2.60 and the build is successful only by adding @ExperimentalMultiplatform annotation to every class or function that uses it. Is there a way around this?

Nikhil

08/16/2018, 6:51 PM

Can someone just tell me how to take the input using standard i/o in kotlin/native ?

Seri

08/16/2018, 8:49 PM

Off the top of my head, this compiles and may be what you’re looking for—

sealed class OutsideGroup {
    class Option1: OutsideGroup()
    class Option2: OutsideGroup()

    sealed class InsideGroup: OutsideGroup() {
        class Option3: InsideGroup()
        class Option4: InsideGroup()
    }
}

fun returnOuter(): OutsideGroup = OutsideGroup.Option1()

fun returnInner(): OutsideGroup.InsideGroup = OutsideGroup.InsideGroup.Option3()

supaham

08/16/2018, 11:53 PM

Is there a slack for intellij generally?

🇳🇴 1

🆗 1

jkbbwr

08/17/2018, 3:00 AM

Why isn't this 255 as expected

jkbbwr

08/17/2018, 3:02 AM

Also

@ExperimentalUnsignedTypes
fun main(args: Array<String>) {
    var a: UByte = 0u
    println(--a) // -1
}

but

@ExperimentalUnsignedTypes
fun main(args: Array<String>) {
    var a: UByte = 0u
    --a
    println(a)  // 255
}

😬 4

:youtrack: 4

karelpeeters

08/17/2018, 10:58 PM

Untitled.kt

👏 1

rahulpr27

08/18/2018, 4:15 AM

Need feedback

Untitled.kt

karelpeeters

08/18/2018, 5:01 PM

You can normal normal Kotlin files with

psvm

in them just fine in AS.

Nikky

08/19/2018, 12:33 PM

i really like suspend and coroutines, but i am really sad that callable references to suspend functions do not work.. that was how i added memoization to those functions.. any idea how to replicate something like that

val cachedCall = ::expensiveCall.memoize()

with suspend functions ?

gmariotti

08/19/2018, 5:31 PM

Hi everyone, does anyone know if there is any plan for a Kotlin compile option

jvmTarget = "11"

? And what would be the implications from a performance/optimization point of view?

david-wg2

08/20/2018, 9:06 AM

is klint the best option?

Matt

08/20/2018, 3:07 PM

Sadly,

Error

includes more than just fatal JVM throwables (e.g.

AssertionError

), which is why Scala has

NonFatal

epool

08/20/2018, 6:53 PM

this code doesn’t complain in compilation time but in runtime if I don’t specify the type of

classLoaders: Array<out ClassLoader>?

when

*classLoaders

is passed as parameter

val classLoaders = reflections.configuration.classLoaders // Array<out ClassLoader>?
ReflectionUtils.forNames<Any>(reflections.allTypes, *classLoaders)

edwardwongtl

08/21/2018, 8:13 AM

val defaults: MutableLiveData<Boolean> = MutableLiveData().apply { value = false }

➕ 1

Bernhard

08/21/2018, 11:10 AM

interface EntityRepository<T> {

    fun fullTextSearch(text: String?, selectedIds: Array<String>?, exclude: Boolean?, size: Int): List<T>

    fun textSearch(text: String?, size: Int): List<T> {
        return fullTextSearch(text, null, null, size)
    }
}

ahegazy

08/21/2018, 1:03 PM

If you have some validation method like

isValidUsername

isValidEmail

, do you feel it’s okay to write this as an extension method to String?

GarouDan

08/21/2018, 5:05 PM

Do we have in Kotlin an easy way to find all inner paths of one specific folder? For example kotlinFunction(‘./folder’) outputs:

./folder/subfolder1
./folder/subfolder2/subfolder21

08/22/2018, 1:22 AM

A bit of a JVM-specific question, but is there a performance difference in using a Canvas in JavaFX versus an ImageView with a BufferedImage back? Which is more performant? (Side note: there are some results on Google which seem to say it's faster to write to a buffered image and others that say canvas. I'm not sure which.)

Can Orhan

08/22/2018, 11:44 AM

Hi! Why is this OK

rebookingList.filter {
        val data = it.data
        when (data) {
            is AccountFeedItem<*> -> {
                data.data is FeedItemTreatment
            }
            else -> false
        }
    }

But this isn't?

rebookingList.filter {
        when (it.data) {
            is AccountFeedItem<*> -> {
                it.data.data is FeedItemTreatment
            }
            else -> false
        }
    }

Viral Thakker

08/22/2018, 1:38 PM

is there any way to check difference between two objects and returned changed property ?

rakeeb

08/22/2018, 3:43 PM

when would you choose to use

let

instead of

run

. I find

run

more convenient, cause of the lamda receiver (no

it

is my reason for choosing it over

let

), but I want to know if I’m using misusing these functions.

diesieben07

08/22/2018, 9:31 PM

How would I best go about producing multiple lists from a single one? Right now I am doing two

map

operations after another, but that requires me to do some computations twice. Do I really have to write a for loop and add to two lists? Example:

val list = listOf(1, 2, 3)
val a = list.map { expensiveOperation(it).value1 }
val b = list.map { expensiveOperation(it).value2 }

Tony Hoyle

08/22/2018, 9:33 PM

Make a list of the pair (value1, value2) then split it?

Krs

08/23/2018, 4:59 AM

Hi guys I have a small question. What happened to Spek? Wasn't it a JB official library?

Bernhard

08/23/2018, 8:37 AM

I've created an interface for the two that I have and I can't define the interface as sealed

Title

Bernhard

08/23/2018, 8:37 AM

I've created an interface for the two that I have and I can't define the interface as sealed

diesieben07

08/23/2018, 8:38 AM

Interfaces cannot be sealed due to JVM constrains. You need an abstract base class that you seal.

Bernhard

08/23/2018, 8:40 AM

I can't have abstract classes for data classes, correct?

gildor

08/23/2018, 8:40 AM

data class cannot be abstract, sure

diesieben07

08/23/2018, 8:40 AM

But data classes cannot be inherited from, period.

But you can do this:

sealed class Sealed {
    data class OptionA(val foo: String) : Sealed()
    data class OptionB(val foo: Int) : Sealed()
}

Bernhard

08/23/2018, 8:43 AM

then use Sealed as type name for OptionA/OptionB?

diesieben07

08/23/2018, 8:44 AM

Yes

Bernhard

08/23/2018, 8:44 AM

ah right, that would require me to do match clauses based on the classes listed

when*

diesieben07

08/23/2018, 8:44 AM

Yes, that's how sealed classes work

Bernhard

08/23/2018, 8:44 AM

thank you

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