Is there no way to construct an anonymous instance...

# announcements

[karelpeeters]

Is there no way to construct an anonymous instance of a SAM-ish abstract class from a lambda? For example:

//java code
public abstract class Test {
    public abstract void run()
}

//kotlin code
fun testFoo(test: Test) = test.run()

fun main(args: Array<String>) {
    testFoo(object : Test() {
        override fun run() {
            println("hey")
        }
    })
}

It just feels unnecessary, are there plans to do something about this?

[emmax]

The preferred way to do that with kotlin is to define that testFoo takes a function to begin with instead of the abstract Test class

I don't see this being supported.
https://kotlinlang.org/docs/reference/java-interop.html#sam-conversions
Note towards the bottom

Also note that this feature works only for Java interop; since Kotlin has proper function types, automatic conversion of functions into implementations of Kotlin interfaces is unnecessary and therefore unsupported.

[karelpeeters]

Yup, unfortunately this is for a Java interop case.

[emmax]

oh gotcha, didn't see Test is a java class 🙂 nvm

[karelpeeters]

I should have specified that, there's no syntax difference in this case.

[emmax]

Well actually, it is defined as a Kotlin class in your example.

[emmax]

abstract fun run()

[emmax]

ah, better 🙂

[karelpeeters]

It's been I while since I wrote any Java 🙂, thanks.

[karelpeeters]

public void feels so ugly now.

[bj0]

You could just pass the lambda into testFoo and create the object in there:

[bj0]

inline fun runnable(crossinline init: Runnable.() -> Unit) = object : Runnable {
    override fun run() = this.init()
}