Random thought. Is there a way to make the class generated from a file (i.e.

Something.kt

->

SomethingKt

) extend a particular type? 🤔

@orangy Interesting bug in the Kotlin Script Parser that might interest you: https://github.com/gradle/kotlin-dsl/issues/928 TL;DR: This code compiles in Kotlin scripts but throws an NPE at runtime:

val first by tasks.creating {
  dependsOn(second)
}
val second by tasks.creating

The most awkward thing which I am facing right now is that I know how to code, but I don't know what does every line of code means. 😞

I have a kotlin closure. I need to pass it as a Java Runnable.

`where`: https://kotlinlang.org/docs/reference/generics.html#upper-bounds

How is

Any

or

Nothing

type mapped at runtime?

But

(Any) -> Unit

is a subtype of

(String) -> Unit

, so you're supposed to be able the always replace the latter with the former if something is taking it.

Is there an advantage to using coroutines in a single threaded context? Like an event loop with one thread (besides syntax)

This message was deleted.

why doesn't this work?

val defaultHandler: Consumer<in Throwable>? = RxJavaPlugins.getErrorHandler()
checkNotNull(defaultHandler)
defaultHandler.accept(Throwable()) // only safe or non-null asserted calls are allowed on nullable receiver of type...

what's the point in this then:

public inline fun <T:Any> checkNotNull(value: T?, lazyMessage: () -> Any): T {
    contract {
        returns() implies (value != null)
    }

do I have to checkout the precise git SHA that caused the crash to make this work?

hi there 1) have data class full nonnullable

data class Info(val id: Int val name: String, val phone: Long)

2) want to have

data class InfoPayload(val id: Int? val name: String?, val phone: Long?)

maybe with some kind of annotation

@payloadable

If no options - I want to ask about compilers plugins for kotlin: can any one share docs for implementation of kotlin-compiler-plugin? tnx

Thanks @gildor! I just started developing a web application in Intellij IDEA, thought of adding coroutines. Got koroutines core.

Hey! Has anyone else noticed the same problem https://youtrack.jetbrains.com/issue/KT-24980 ?

Hey everyone! Can anyone here give me a list of objective facts that makes Kotlin better than Java? I’m trying to push Kotlin use at work but I keep running into arguments of people saying “but everyone else uses Java, so why not Java?“. I feel like most people are just afraid of change. Has anyone else dealt with similar situations, and if so, how did you deal with it?

Noob question: can i use the common module, from a non-multiplatform code? For example, from Kotlin/jvm. If there is no "expect" classes yet

Did you understand why it would be ambiguous to

addAll(vararg)

? I didn't quite see a possible confusion there

My last talk

Anyone notice any code smells here? I was messing around trying to get an

unless

-like operator:

sealed class Unless {
  object unless : Unless() {
    override val run: Boolean = false
  }
  
  object other : Unless() {
    override val run: Boolean = true
  }
  
  abstract val run: Boolean
}

inline infix fun Unless.otherwise(block: () -> Unit) {
  if(run) block()
}

inline fun unless(predicate: Boolean, block: () -> Unit): Unless =
    if(!predicate) {
      block(); Unless.unless
    }
    else {
      Unless.other
    }

Why Kotlin does not have built in support for binary operations on Byte ? I tried code like this

val b1: Byte = 2
        val b3: Byte = 7
        val b4 = b1 xor b3

and IDEA suggested

import kotlin.experimental.xor

, but when I tried this:

val b1: Byte = 2
        val b3: Byte = 7
        val b4 = b1 shl b3

it does not have even anything to suggest. It is sad as I’m implementing CRC calculation that requires quite a lot of binary operations on bytes an each time I have to cast my bytes…. I do realise that it is possible to write extension. But I’m still wandering why Byte is not treated the same way Int and Long is?

@karelpeeters I'm talking about

fun foo() = print("hello")

vs.

fun foo() { print("hello") }

Hi! I´m wondering if it´s possible create a constructor that throws a exception in some cases? Anyone could tell me how can I achieve this?? Thanks in advance

data class User(
        val name: String? = null,
        val address: String? = null,
        val phone: String? = null
)

Suppose I have a data class like above I am validating properties name, address, phone as not null So if its not null how can i change its type to NotNullable because if i use this data class in anywhere else i always have to use !! or ? despite of its already validated for null check. so that data class after validation looks like

data class User(
        val name: String,
        val address: String,
        val phone: String
)

Anybody faced this problem ?

maybe this’ll end up being a dumb question, but what’s the right approach to take when you have a property you want to assign conditionally based on which constructor you call? the class I’m writing kinda looks like this

class Foo(val bar, val baz) {
  val doober = mutableMapOf<String, String>()
  val qux: Set<String>
  constructor(bar, baz, lad) : this(bar, baz) {
    // do things to `doober` using `lad`
    qux = doober.keys.toSet()
  }
}

more specifically,

qux

should be an empty set if the primary constructor is called, and a computed, read-only set if the secondary constructor is called, based on the results of evaluating the parameter unique to it. I tried a separate

init

block declared after the secondary constructor to populate the set using the map, but it looks like the init block gets executed before the logic in the body of the secondary constructor. for kicks, I also tried making

qux

a constructor parameter, but you can’t call the primary constructor from the secondary one using values you compute in the latter

Think I've found a compiler bug. Is this the place for it?

is there any way to get the second way to work?

after upgrading from 1.2.41 to 1.2.50, when I run only 1 junit method, I get this error

Error:Kotlin: [Internal Error] java.lang.IllegalStateException: The provided plugin org.jetbrains.kotlin.scripting.compiler.plugin.ScriptingCompilerConfigurationComponentRegistrar is not compatible with this version of compiler
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment.<init>(KotlinCoreEnvironment.kt:186)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment.<init>(KotlinCoreEnvironment.kt:119)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment$Companion.createForProduction(KotlinCoreEnvironment.kt:418)
	at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.createCoreEnvironment(K2JVMCompiler.kt:265)
	at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:154)
	at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:63)
	at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.java:107)
	at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.java:51)
	at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:96)
	at org.jetbrains.kotlin.daemon.CompileServiceImpl$compile$$inlined$ifAlive$lambda$1.invoke(CompileServiceImpl.kt:399)
	at org.jetbrains.kotlin.daemon.CompileServiceImpl$compile$$inlined$ifAlive$lambda$1.invoke(CompileServiceImpl.kt:98)
	at org.jetbrains.kotlin.daemon.CompileServiceImpl$doCompile$$inlined$ifAlive$lambda$2.invoke(CompileServiceImpl.kt:920)
	at org.jetbrains.kotlin.daemon.CompileServiceImpl$doCompile$$inlined$ifAlive$lambda$2.invoke(CompileServiceImpl.kt:98)
	at org.jetbrains.kotlin.daemon.common.DummyProfiler.withMeasure(PerfUtils.kt:137)
	at org.jetbrains.kotlin.daemon.CompileServiceImpl.checkedCompile(CompileServiceImpl.kt:950)
	at org.jetbrains.kotlin.daemon.CompileServiceImpl.doCompile(CompileServiceImpl.kt:919)
	at org.jetbrains.kotlin.daemon.CompileServiceImpl.compile(CompileServiceImpl.kt:397)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:357)
	at sun.rmi.transport.Transport$1.run(Transport.java:200)
	at sun.rmi.transport.Transport$1.run(Transport.java:197)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
	at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:573)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:835)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:688)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:687)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.AbstractMethodError
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment.<init>(KotlinCoreEnvironment.kt:184)
	... 33 more

I have this function

fun findProfile(user: UserDocument, vararg fields: String) { ... }

I'd like to make the vararg parameter required, because if I call that method like

userService.findProfile(user)

it doesn't complain. Any idea?

how do you usually deal with interoperability when it makes sense for kotlin to return

String?

, but it makes sense for java to return

Optional<String>

?