@damian: No, it's currently not supported. There is an open issue for this: https://youtrack.jetbrains.com/issue/KT-83

Wow, issue 83. thanks simple smile

public companion object Singleton: SomeInterface by internalInstance {
    val internalInstance: SomeInterface = SomeInterfaceImplementor()
}

Is there any way to make delegating to a member variable work? This snippet produces the error

Variable 'internalInstance' must be initialized

although it seems like it should be initialized? Is there something that happens before vals are initialized during object creation that would cause issues?

Hey all

Why does

Map<String, Any>

become

Map<String, ?>

in Java

I’m trying to find a library that I found last week that I can’t remember the name of it. It had a DSL like the following

{function1()} and {function2()}

which would cause function1 and function2 to be calle din parallel. It could then also wait for responses.

I can’t remember the name of it

If I try to use Map<String, Object> then It offers

Map<String, ? extends Object>

because of how Kotlin generics works. you can modify that by using the ‘in’ and ‘out’ modifiers

see here: https://kotlinlang.org/docs/reference/generics.html

question - is there a way to allow an outer class to see private members of an inner class in kotlin, like in Java?

or do I need to subclass the inner class with a private version and handout the superclass?

But it says that

out

is implicit in Map<String, Any>

what type signature do you actually want in java?

Map<String, Object>

fun register(type: Int, txFactory: (data: Map<String, Any>) -> ITransaction)

is the method signature

From javaland I want that Map to be <String, Object>

we’ll soon have an annotation that will allow you to tell Kotlin not to generate the wildcard in the Java signature

So I need to have Map<String, ?> on the java side for now?

Hi all. I'm trying to use Kotlin in simple JavaFX application. But I can't call val canvas = Canvas(400, 200) case "the integer literal does not conform to the expected type kotlin.Double" Is it no type coversion from int to double in kotlin?

no

you need to write

400.0, 200.0

thank you.

@natpryce and @mikehearn : you can use a classifier, which is recommended in the Maven and Gradle docs and is one of the samples given for the use of a classifier is the jdk version. It is the 4th part of a maven artifact identifier

groupId:artifactId:packaging:classifier:version

… given both build systems mention that, and it is common in Ivy as well to use classifiers, then there IS a way to do this that is standard.

>> classifier:

The classifier allows to distinguish artifacts that were built from the same POM but differ in their content. It is some optional and arbitrary string that - if present - is appended to the artifact name just after the version number. As a motivation for this element, consider for example a project that offers an artifact targeting JRE 1.5 but at the same time also an artifact that still supports JRE 1.4. The first artifact could be equipped with the classifier jdk15 and the second one with jdk14 such that clients can choose which one to use. Another common use case for classifiers is the need to attach secondary artifacts to the project's main artifact. If you browse the Maven central repository, you will notice that the classifiers sources and javadoc are used to deploy the project source code and API docs along with the packaged class files.

I think the new gradle “model” with multi-platform build appends something similar, but not sure if it uses classifier

(need to try it out)

This is the new model in Gradle: https://docs.gradle.org/current/userguide/building_java_libraries.html

So I have been a lover of Guava for the last few years. One thing that has blown me away about Kotlin is that it makes Guava obsolete because it has extensions types. Am I understanding this correctly?