simplify kotlin example in documentation

[virtuald]

Instead of

@Command
class MyApp {
    ...
    companion object {
        @JvmStatic fun main(args: Array<String>) {
            CommandLine.run(MyApp(), System.err, *args)
        }
    }
}

It's easier to do this instead:

@Command
class MyApp {
    ... 
}

fun main(args: Array<String>) = CommandLine.run(MyApp(), System.err, *args)

Idea borrowed from clikt's documentation.

[remkop]

Nice! Will you be able to provide a pull request for this?

[virtuald]

Sure... where do the docs live?

[remkop]

docs/index.adoc

[virtuald]

Oops, I meant to do it today but got busy... thanks!

[remkop]

No problem at all! Thanks for the suggestion!

[lpar]

Hmm, maybe this worked at the time, but it doesn't work now:

fun main(args: Array<String>) = CommandLine(MyApp()).execute(*args)

Because execute returns an int, Kotlin deduces that main returns an int, so you get a warning saying that main should return Unit. If you ignore that you get a run-time error:

Error: Main method must return a value of type void in class mypkg.MyAppKt, please
define the main method as:
public static void main(String[] args)

So I think it should be

fun main(args: Array<String>) {
  CommandLine(MyApp()).execute(*args)
}

[remkop]

@lpar, thanks for catching that!
My bad, I didn’t verify the Kotlin example with the new execute API.
I’ll fix this as soon as possible.

[remkop]

@lpar Thanks again for the bug report!
I fixed the user manual.