When I

gradle build

My source files aren't actually compiled

huh, and there we go

shadow plugin was screwing with something

Hi. There is something i been wondering for a while: why does

as?

gives Unchecked Cast warning? Isn't

instance as? MyClass

pretty much a shortcut for

if(instance is MyClass) instance as MyClass else null

which IS the checked cast?

Does the compiler emit that warning too? It shouldn't happen, the cast is indeed safe.

I think this happens if the class you cast to is an array with non-null elements, because the compiler can't guarantee the nullability of its elements. This will compile with an unchecked warning and will fail with a NPE at runtime:

val array = arrayOf(1,2, null)
(array as? Array<Int>)?.forEach(::println)

Hmm, i see... I guess i idn't consider such extreme cases

I think you get the warning if you cast to any generic class.

This also gives the warning and fails at runtime:

data class Container<T>(val t: T)
val container = Container(null)
(container as? Container<Int>)?.let { it.t.toString() }

Technically you always need to do

java -jar ...

, but the gradle application plugin can hide that in some batch and sh files really easily, it works for Windows, Linux and iOS.

(it works for Java too)

Ah, so I just add something like "Make it easy to run this from command line" to my gradle file and it adds some scripts to the build?

Alright, sounds good enough, I'll look it up.

yea it is super nice and can package stuff up for you so if you don’t want to do scripts you can still ship a fat jar

@rednifre there's kotlin native, once it's released I guess it will be possible to build a true executable from it

Yeah, or I just compile Kotlin to Javascript and decompile that to CoffeeScript which uses "#" for comment lines so I can add a #! at the beginning to run it with the coffeescript interpreter... 😉

kscript ->

#!/usr/bin/env kscript

or just use a super simple shell script that runs your kotlin program?

kscript

looks interesting though, I'll look into that

@ziggy42 That's what the gradle application plugin does for you pretty much.

@karelpeeters yes but you probably want to run something like

$ ./myprogram

intead of

$ ./gradlew run

Right so that's why there's a task "gradle distZip" that compiles everything and creates a zip file with in it all of the dependencies and a bat and sh file that actually run the code.

So you could indeed do

$./myprogram

@ziggy42

I didn't know this for a long time too, I was amazed that it was suddenly so easy to distribute something 🙂

As this starts to be a real plague among fresh Kotliners. I’d love to remove it, or at least treat it as an error in IntelliJ?

one could build an inspection for it (really trivial) and set it to disabled by default.

you could create a youtrack issue. would be a fun little project for someone wanting to contribute to kotlin

Doesn't Idea have a warning for it already? You can set the severity or whatever it's called to "error"

Nope I was wrong, there isn't one.