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announcements

robstoll

04/06/2018, 12:55 PM

is there a way to escape $ in a triple quote string?

Shawn

04/06/2018, 1:04 PM

@dekans the java way, probably

private val _list: MutableList<T>
val list: List<T> = _list

Jeevan

04/06/2018, 2:34 PM

https://kotlinlang.slack.com/archives/C0922A726/p1523019871000373

04/06/2018, 3:13 PM

once you know the rules the behavior should be obvious. it's equally troublesome in Java. the API design is setting you up for failure

👆 3

👍 2

Shawn

04/06/2018, 3:54 PM

but, uh, how young are we talking?

andreworobator

04/06/2018, 6:42 PM

fun bindView(
    position: Int,
    view: ListItemView // Interface
  ) = when (ViewTypeEnum.values()[position]) {
    ENUM1 -> bindViewType1(view as ViewType1)
    ENUM2 -> bindViewType2(view as ViewType2)
  }

andreworobator

04/06/2018, 6:58 PM

This is the pattern I’m following: https://android.jlelse.eu/recyclerview-in-mvp-passive-views-approach-8dd74633158

makarezp

04/06/2018, 8:04 PM

I’d like to start contributing to kotlin, any advice?

muralimohan962

04/07/2018, 6:41 AM

Why doesn't Kotlin have any keyword like synchronized for synchronization? Why do they ask us to use @Synchronized annotation?

barteks2x

04/08/2018, 7:14 PM

is there a way to do this without making my own class?

class LazyToString(val obj: () -> Any) {
    override fun toString(): String {
        return obj().toString()
    }
}

thing = LazyToString { doThing() }

pakoito

04/08/2018, 7:55 PM

how do you

@parameter

refer to the type the extension is in?

gildor

04/09/2018, 2:48 AM

moshi doesn’t throw by default, you need kotshi for that: https://github.com/ansman/kotshi

pike

04/09/2018, 4:24 AM

I changed it to strings: for (i in 1..101) println(“${if(i%3 == 0) “fizz” else “”}${if(i%5==0) “buzz” else i.toString()}“)

diesieben07

04/09/2018, 8:22 AM

Which is essentially a union type

mzgreen

04/09/2018, 8:22 AM

you’re right, they are often used with aliases though

louiscad

04/09/2018, 9:05 AM

@gildor I just thought about renaming a class in a library, and I thought I can use a deprecated typealias for the old name to keep source compatibility (not binary though). Also, I had to replace Google Maps by MapBox in a project, MapBox being basically a copy pasted API, with some differences, and some extra/missing features, and I thought I could use a typealias to swap one with another anytime.

jakubgruber

04/09/2018, 9:25 AM

What is difference between

@JvmField

and

const

? Is property exposed to Java as a static if

const

is used? Android Studio recommended that to me, so just asking 🙂

marstran

04/09/2018, 10:36 AM

The

copy

function only copies the constructor parameters. You should do this:

data class Person(val name: String = "Tristan", val age: Int = 1)

fun main(args: Array<String>) {
    val person = Person()
    val personCloned = person.copy(age = 3)
    println(personCloned.age)
}

adams2

04/09/2018, 2:06 PM

how do I debug kapt itself

adams2

04/09/2018, 2:06 PM

it's crashing with an NPE at some sun.* packages

Jacks0n23

04/09/2018, 2:13 PM

Are i understand something wrong or it's kotlin bug? I have : data class Foo ( val initializationType: InitializationType) { val isInitDefault = initializationType == InitializationType.Default } and when i call this val it's working incorrect, but when i transform it to fun or just add custom get() = initializationType == InitializationType.Default it start working like it should what the problem? P.S. InitializationType it's enum

karelpeeters

04/09/2018, 7:27 PM

Can you give an example of such a context?

makarezp

04/09/2018, 7:47 PM

Hi, I am trying to work on Kotlin source on idea ultimate, I have followed the instruction from readme.md, I’ve opened project, added the module from existing sources, but it seems that idea can’t resolve dependencies in build.gradle.kts. All gradle builds are working properly. So if I run ./gradlew coreLibTest it’s compiling and running, but if I try to run tests from idea I’m getting errors. I’ve got 2018.1 build.

Hemanth

04/10/2018, 7:02 AM

HI, any references to read credit card number from camera?

🤦 2

:stackoverflow: 9

Tarun

04/10/2018, 9:17 AM

Hey I am working on a library in Kotlin In this library, if I have some variable inside

companion object

, than those variable are treated as static in Java But when I try to access those variable in a java project, which is using library, It is like :

MyClass.Companion.abcVariable

I searched and found I had to append @JvmStatic in front of variable so that java can access it directly like :

MyClass.abcVariable

This works for

classes

but for

interfaces

it requires a min API level of 24 and my Min API level is 21 Is there any other way to directly access companion object variables for

interface

in API projects supporting min API level less than 24 like :

MyClass.abcVariable

Rich Gabrielli

04/10/2018, 8:32 PM

Thanks for the explanation, but I am a bit confused. I am new to Kotlin and Slack. If not in general or android, should it be getting started? I do not see a stackoverflow

pavel

04/10/2018, 9:39 PM

or you could add a

by Delegates.notNull()

➕ 1

edwardwongtl

04/11/2018, 3:48 AM

Is there a way to limit function invocation using something like

fun doSth(action: Mode.() -> Unit)

? But

Mode

contains only functions, no properties. Although it is completely fine to create instance of

Mode

and pass it to

action(mode)

, it just doesn't quite make sense for me to create such a instance.

louiscad

04/11/2018, 8:13 AM

I do not have experience in writing in C# at the moment, but it seems like this language is a bit more verbose than Kotlin, hence my question. I got interested in developing on Unity 3D since I saw Google Maps gaming API is coming. I guess I'll try with C# when time comes to play with it then, thank you

Jon

04/11/2018, 9:37 AM

Is it possible to constrain a List guaranteeing that it always contains at least one element? Currently I use

require

init

of the class it's in, but the compiler doesn't know that this invariant exists so still requires null-safety checks.

Title

Jon

04/11/2018, 9:37 AM

Is it possible to constrain a List guaranteeing that it always contains at least one element? Currently I use

require

init

of the class it's in, but the compiler doesn't know that this invariant exists so still requires null-safety checks.

karelpeeters

04/11/2018, 9:51 AM

I don't think that's possible unfortunately.

Andreas Sinz

04/11/2018, 12:30 PM

What null-safety check are you refering to?

SiebelsTim

04/11/2018, 1:20 PM

build your own list-type, that needs at least one element in the constructor

gildor

04/11/2018, 3:55 PM

For example of such non empty list implementation you can take a look on NonEmptyList from Arrow https://github.com/arrow-kt/arrow/blob/master/modules/core/arrow-data/src/main/kotlin/arrow/data/NonEmptyList.kt

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