kotlinlang #announcements

The Observer is from the package "androidx.lifecycle" and looks like this public interface Observer<T> { void onChanged(T t); } Why the Observer compiles but Sample does not compile? Error is 'Interface Sample does not have constructors'

Sample___Observer_-_what_is_the_difference_.js

tapchicoma

04/12/2019, 5:44 PM

Would be nice to update https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md with new

1.3.30

version 🙂

gaetan

04/12/2019, 9:45 PM

Is it possible to do remote debug in Kotlin? I don’t find it.

Robert

04/13/2019, 8:13 PM

Why CAN I use

1L and 1

, but CAN'T I use

1 and 1L

? Can I somehow globally add the infix myself (i tried, but it has to be in the same package or something)? Like this

inline infix fun Int.and(long: Long) = this.toLong() and long

Hullaballoonatic

04/13/2019, 10:18 PM

I'm really hoping this is added soon (default values for type parameters): https://discuss.kotlinlang.org/t/allow-typealias-to-have-the-same-name-as-generic-class/6789/6 The example provided by Andrey Breslav in the post is:

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class Foo<T : Bar = Baz>

Hullaballoonatic

04/13/2019, 10:38 PM

I wonder if we can also get something like javascript's "everything else" usage of the spread operator, e.g.

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val (id, *contents) = line.split(",").map { it.trim() }

➕ 2

Hullaballoonatic

04/14/2019, 3:26 AM

Join JetBrains? 😛

😂 4

Hullaballoonatic

04/14/2019, 3:28 AM

I write almost every project in which I'm allowed to write in any language in Kotlin, because it is absolutely the best programming language now

Smallville7123

04/14/2019, 5:15 PM

why do i get this?

Type mismatch: inferred type is T#2 (type parameter of preprocessor.utils.core.algorithms.LinkedList)? but T#1 (type parameter of preprocessor.utils.core.algorithms.LinkedList.LinkedListIterator)? was expected

Smallville7123

04/14/2019, 5:16 PM

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inner class LinkedListIterator<T>() {
        var node = head
        fun hasNext(): Boolean {
            if (node != null) {
                if (node?.next != null) return true
            }
            return false
        }
        fun next(): T? {
            if (node != null) {
                if (node?.next != null) {
                    return node?.value
                }
            }
            node = node?.next
            return null
        }
    }

    fun iterator() : LinkedListIterator<T> = LinkedListIterator()

karelpeeters

04/14/2019, 5:53 PM

Your outer class probably also has a parameter

<T>

, and your inner class is shadowing that one. You probably don't want an independent one for the inner class, so remove that.

Smallville7123

04/15/2019, 2:55 AM

Smallville7123

04/15/2019, 4:33 AM

like,

class A, forEach

or something

Smallville7123

04/15/2019, 4:34 AM

also would i need to do the same for

.iterator

aswell then override it in the class

Smallville7123

04/15/2019, 4:36 AM

like...

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class A, iterator, forEach {
    override fun iterator() = LinkedListIterator()
}

or something

Alowaniak

04/15/2019, 5:50 AM

There is no duck-typing in kotlin so you can't have an extension method based only on a class containing a method You can only extend existing types However usually a class that has iterator will/should implement Iterable I would say

Alowaniak

04/15/2019, 5:54 AM

So you could make an extension method for Iterable (eg.

fun Iterable.foo()

...) However in case of

forEach

I'm relatively sure there is one on Iterable already

➕ 1

Smallville7123

04/15/2019, 6:16 AM

how do i correctly implement kotlin.collections.Iterable

Smallville7123

04/15/2019, 6:20 AM

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class LinkedList<T> : kotlin.collections.Iterable<T> {

    object i : kotlin.collections.Iterator<T> {
        override fun hasNext(): Boolean {
            TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
        }

        override fun next(): T {
            TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
        }

    }
    
    override fun iterator(): kotlin.collections.Iterator<T> {
        return i
    }

/home/macropreprocessor/IdeaProjects/kpp/src/linuxMain/kotlin/preprocessor/utils/core/algorithms/LinkedList.kt: (5, 44): Unresolved reference: T

for

object i : kotlin.collections.Iterator<T> {

🧵 2