Hi all, probably it was already answered, but I wasn't able to find any discussion about it. So my question relies on smart casts of class properties. As we know, smart cast of mutable property of nullable type isn't possible (

Smart cast to Type is impossible because propertyName is a mutable property that could have been changed by this time

. It relies on fact, that between checking for null and call to property value could have been changed by another thread. Proposed solution is to bake reference in a local variable and operate with it. It is great that developers of languages thought about situation of shared states between two threads, but it's really awkward to see this message in a program which operates in main thread only. Having to bake all properties seems really redundant in this scenario. So my question is: is there any plan to introduce some way to mark property as thread safe? At least some annotation which will turn off this check?

@rook Is lateinit not threadsafe?

Hey, I thought

lazy

was doing it

synchronized

? Isn't it supposed to be thread safe?

safe call question on nullable variable: Let’s say I have a variable of type

List<String>?

and I want to check that it contains at least one element. Is it possible to use just one condition check? I’ve tried:

val t: List<String>? = null
println(t?.size != 0)

and this prints

true

, which is not what I want. I tried:

!t?.size?.equals(0)

but I can’t use this in an

if

because it’s

Boolean?

.

Another question: this code snipped:

fun doStuff(input:String) {
   val split = input.split("foo", 0)
}

will not compile, but this one:

fun doStuff(input:String) {
   val split = java.lang.String(input).split("foo", 0)
}

will be OK. Is it supposed behaviour (in other words, is it a bug or is it a feature)?

For some reason, I can't figure out what is going on here:

class Ref<K: Comparable<K>, T>(val key: K, val value: T) : Comparable<Ref<K, T>> {
    override fun compareTo(other: Ref<K, T>) = key.compareTo(other.key)
}

fun main(args: Array<String>) {
    val list = mutableListOf<Ref<Int, *>>()
    list.sorted()  // ERROR: Ref<Int, *> is not a subtype of Comparable<Ref<Int, *>>
}

Any ideas?

(Also, I know

sortedBy { it.key }

works. I'm trying to understand why

*

doesn't)

that should be a bug. clearly a CAT is a decrement, not an increment

What JVM version?

Submitted the issue, feel free to add additional context if you have any https://youtrack.jetbrains.net/issue/KT-24800

@karelpeeters the challenge is the following. The

foo

field is injected via DI, so it has to be lateinit. The thing is, this field is used to build another one —

bar

. That's why the

bar

is lazy.

@Inject
    lateinit var foo

    val bar by lazy {  foo.foo()   }

Now, I'm wondering if I can hide all this trickery behind some delegate or something, so I'll end up with a clean

bar

initialization. Ideal:

val bar by initBar() // somehow foo is injected inside?

Or at least:

@Inject
    lateinit var foo

    val bar by initBar(foo)

Does Exception/Throwable have a special status of same kind? Would it be okay to carry an additional state and functionality within Exception class?

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Hi, I have an issue using some obfuscated code (net.minecraft.server): I'm trying to call this functions

DataWatcherRegistry.b.a(7)

but there is a conflict because there are two functions named

a

. One returns

DataWatcherObject<T>

(the one I want) and another returns

T

. How can I select the correct one, because right now, I'm getting some conflicts.

that isn't a Kotlin-specific question.

Call

is a representation of the pending request and its execution mechanism (which can either be synchronous or asynchronous).

ResponseBody

is the body type, which in this case is a general wrapper around any HTTP response that will allow you to interpret it as bytes or a string or a stream.

Kotlin named as one of the top languages to learn by IDG TechWorld: https://www.techworld.com/picture-gallery/careers/up-coming-programming-languages-for-developers-get-grips-with-3621455/

any working code example maybe? 😉

Imo explicit type declaration is good idea sometimes. Would be interesting to see real example

Anyone know the answer to https://discuss.kotlinlang.org/t/how-do-i-type-square-bracket-proper-in-kdoc/6906?

inside the option 2, you could also emit the getter and the setter and create a facade property in the object it self

What would you recommend for cross platform UI development?

I'm really looking for: "here is a bunch of failing unit tests; go fox it"

I have a Map of <String, Object>, where the key string can be converted into an integer index <Int, Object> then I want to sort by the Int index and order the object to get a List<Object>. Is there a functional way to write that? Can I do a map on a Map and get a Map as the result?

something something great minds

My current approach for deploying kotlin functions to lambda requires running "aws lambda create-function ..." I already have done "aws configure" Is there a way to, in kotlin, right click a function and choose "deply on lambda with name ..." ?//

i’m having some issues with a deprecated function’s

ReplaceWith

argument. alt-enter is simply deleting the line i’m on, rather than changing it to what’s specified in

ReplaceWith

is there any reason to prefer null over empty collection as return value in kotlin?

how do you represent '\0' in Kotlin? The compiler throws an error mentioning illegal escape for '\0'