kotlinlang #stdlib

It probably doesn’t need it in general, I was mostly curious… I’ve only just had to do it for the first time in Kotlin. My use case (Android/Skia specific) is drawing lines on a canvas using a

FloatArray

of points.

damian

11/19/2015, 3:35 PM

Untitled.scala

11/19/2015, 5:04 PM

@damian: generally graphics APIs that accept arrays are providing ability to specify offset and length

11/19/2015, 5:04 PM

android's canvas is not an exception: http://developer.android.com/reference/android/graphics/Canvas.html#drawLines%28float[],%20int,%20int,%20android.graphics.Paint%29

11/19/2015, 5:05 PM

so you probably don't need to copy arrays except you want to concatenate many points from many many ranges

damian

11/19/2015, 5:15 PM

I am aware of the Canvas APIs, but I do have to do a bit of concatenation and moving things around manually ¯\_(ツ)_/¯

jkwatson

11/20/2015, 4:08 AM

I would love to have a version of

with

that took a

T -> Unit

function and returned the receiver. It’s a lot like

apply

but reads (to my eyes) a little more naturally.

jkwatson

11/20/2015, 4:09 AM

It’s very useful for interacting with legacy java API objects that require you to construct them and call a bunch of setters on them before they are useful.

natpryce

11/20/2015, 7:57 AM

Usual convention in Java is for "with" to mean returns a new object with changes from some original object.

natpryce

11/20/2015, 7:58 AM

Eg address.withPostcode(x) would return a copy of address but with a postcode of x

natpryce

11/20/2015, 7:58 AM

Maybe "set" or "init" would be a good name.

natpryce

11/20/2015, 7:59 AM

val cxn = Connection(url).init {auth(username, password)}

dh44t

11/20/2015, 8:30 AM

I use “with” in other places, not just for initialization

natpryce

11/20/2015, 9:44 AM

Q: will the Kotlin stdlib ever include support for Java 8 types?

natpryce

11/20/2015, 9:44 AM

that is, types introduced in Java 8

ylemoigne

11/20/2015, 9:47 AM

Or in an optional stdlib… like dependencies become “stdlib”, “stdlib-java8extensions"

natpryce

11/20/2015, 9:55 AM

That would be good

natpryce

11/20/2015, 9:55 AM

At the moment I’m writing my own extension methods whenever I find the need, but it would be good for them all to be done for me!

mikehearn

11/20/2015, 11:28 AM

@natpryce: sounds like a good github project that everyone could contribute to

mikehearn

11/20/2015, 11:28 AM

@natpryce: what classes are you extending? i find the java 8 apis to be pretty complete already

kirillrakhman

11/20/2015, 11:53 AM

@jkwatson: Your version would read

val foo = Foo() with { it.initMethod() }

whereas

apply

reads

val foo = Foo() apply { initMethod() }

. I don't see the benefit

natpryce

11/20/2015, 12:13 PM

I’m thinking of .use for AutoClosable, instead of just java.io.Closable

natpryce

11/20/2015, 12:13 PM

etc.

ilya.gorbunov

11/20/2015, 1:25 PM

We'll provide such

use

extension in stdlib addon for java8

natpryce

11/20/2015, 2:02 PM

Great!

vandalko

11/20/2015, 2:53 PM

Hi. Is there any way to submit an issue or seek any help regarding kapt (annotation processing) ? I'm having issue using generated classes with Dagger...

jkwatson

11/20/2015, 3:11 PM

@kirillrakhman: I think for me, I prefer the function on the left, rather than in between the receiver and the closure. I’d like

let

to be on the left, as well. simple smile

jkwatson

11/20/2015, 3:12 PM

I’d be ok with a version of

apply

that worked on the left side, too.

jkwatson

11/20/2015, 3:12 PM

Either way, I can easily put those versions in my own project, but putting them in stdlib seems reasonable to me, to give some usage options to the programmer