Hi everyone, In our latest 1.3.20 EAP, we have add...

# multiplatform

[h0tk3y]

Hi everyone,
In our latest 1.3.20 EAP, we have added Gradle Kotlin DSL support to the kotlin-multiplatform plugin, along with some DSL improvements, such as simpler targets declaration.
You're welcome to try it and share your feedback!
See the details in the thread.

[h0tk3y]

To try this build, you need to add the Kotlin EAP repository to the pluginManagement { ... } section of the settings.gradle file:

pluginManagement {
    repositories {
        maven { setUrl("<https://kotlin.bintray.com/kotlin-eap>") }
        gradlePluginPortal() 
	}
}

Add this repository to the build script as well and apply the plugin within the plugins { ... } block as you normally would, but specify the EAP version:

plugins {
    kotlin("multiplatform") version "1.3.20-eap-25"
}
repositories {
    maven { setUrl("<https://kotlin.bintray.com/kotlin-eap>") }
}

[h0tk3y]

The DSL improvements in the EAP that are available both in Groovy and Kotlin DSL are:

* simpler target declaration: instead of fromPreset(presets.<...>, '...'), you can now use functions: for example, jvm { ... } or jvm('jvm6') { ... } or even jvm(), and similarly for the other platforms. This works in the whole kotlin { ... } scope, not only in the targets { ... } block. If such a target already exists, these functions return it, which can be used to access or configure an existing target: jvm().compilations.<...>.

* an equivalent for targets { fromPreset(...) } in case you need to dynamically create multiple targets from several presets: `targetFromPreset(...)`;

* defaultSourceSet and defaultSourceSet { ... } as a less error-prone way to configure a default source set of a compilation: `jvm().compilations["main"].defaultSourceSet { ... }`;

* statically typed kotlinOptions, kotlinOptions { ... }, and compileKotlinTask for a `KotlinCompilation`;

* shorthands for Kotlin dependencies, like kotlin('stdlib') instead of 'org.jetbrains.kotlin:kotlin-stdlib'.

[addamsson]

this is awesome!

[thevery]

@h0tk3y could you please update https://github.com/h0tk3y/k-new-mpp-samples, too?

[serebit]

Love the new MPP Kotlin DSL changes! Only thing I'm really missing is a function with the following signature:

fun KotlinDependencyHandler.implementation(group: String, name: String, version: String)

[h0tk3y]

@thevery Ok, I've added some superficial update to that repo, maybe will add Kotlin DSL samples later.

[msink]

What Gradle version will be used in Jetbrains libs - .coroutines, .serialization etc, 5.0?
Now they use 4.7.

[gildor]

Side note,

maven { setUrl("<https://kotlin.bintray.com/kotlin-eap>") }

Can be replaced with just

maven("<https://kotlin.bintray.com/kotlin-eap>")

[gildor]

@h0tk3y What do you think about main/test static accessors, or set of type safe extensions, like:

fun KotlinOnlyTarget<*>.dependenciesMain(block: KotlinDependencyHandler.() -> Unit) {
    compilations["main"].defaultSourceSet {
        dependencies {
            block()
        }
    }
}

[gildor]

Because compilations["main"].defaultSourceSet { is pretty wordy and you need a lot of such code

[h0tk3y]

@gildor Yes that makes sense. Though Android doesn't have a main compilation, so this kind of extension won't be available for Android targets. I've created an issue for this: https://youtrack.jetbrains.com/issue/KT-28866

[pajatopmr]

I am attempting to convert …/k-new-mpp-samples/lib-and-app/sample-lib to use the Kotlin DSL, plus make a few updates. I get an error as shown: Screen Shot 2018-12-27 at 5.42.38 PM.png

[pajatopmr]

Any clues on how to fix the remaining errors?

[pajatopmr]

Script compilation errors:

Line 35: nativeMain
^ Unresolved reference: nativeMain

Line 37: configure([linuxMain, windowsMain, macMain]) {
^ Type mismatch: inferred type is Array<TypeVariable(T)> but (Mutable)Iterable<Any!> was expected

[serebit]

well there’s no nativeMain property, you have to do get(“nativeMain”)

[serebit]

and configure in that lambda

[pajatopmr]

| “and configure in that lambda”

[pajatopmr]

@serebit Can you elaborate just a tad more, thanks.

[serebit]

Sure. Before the newest EAP, the way to access any source set was get(“${targetName}Main”) or get(“${targetName}Test”, like windowsMain and linuxMain. I wasn’t clear in my other message, sorry.

[serebit]

If you wanted to configure them all, I’m not sure if this would work, but try replacing [linuxMain, windowsMain, macMain] with mutableListOf(get(“linuxMain”), get(“macMain”), get(“windowsMain”)).

[serebit]

I don’t have my laptop with me to give it a shot myself, but I can take a look later.

[pajatopmr]

Appreciate the attempt. Fwiw, the following shows the best that I can conjure up which at least gets rid of the script errors but still has a build error:

[pajatopmr]

Screen Shot 2018-12-28 at 12.24.24 AM.png

[gildor]

@pajatopmr But what is nativeMain? There is no target with name “native” in you config

[pajatopmr]

I’m not sure how to answer that question, especially since the code is an attempt to transform the original Groovy script into Kotlin. Perhaps @h0tk3y can answer.

[gildor]

So I believe this is expected error, because you cannot configure non-existing target source set

[pajatopmr]

But the Groovy script works fine. I’m still learning but if I have it right, the three statements on lines 20-22 define the targets and the getByName("nativeMain")... is defining the source set, associating it with the three native targets. Feel free to correct my understanding.

[gildor]

Just print all available source sets:

println(asMap.values)

[pajatopmr]

This is what I get:

Values: [source set commonMain, source set commonTest, source set jvmMain, source set jvmTest, source set linuxMain, source set linuxTest, source set macMain, source set macTest, source set windowsMain, source set windowsTest]!

[gildor]

so no “nativeMain”

[gildor]

actually you need asMap.keys, sorry

[gildor]

Did you try this config on Groovy with the same MPP plugin version? Maybe something changes

[pajatopmr]

It’s pretty clear that the intent in the sourceSets block is to associate the native source sets with the directory src/nativeMain but how that association is supposed to be made is not clear to me.

[pajatopmr]

This script works fine with the Groovy code. It is my inept translation to Kotlin code that is the issue. And I plead guilty to barely knowing what I am doing here.

[pajatopmr]

It might have been missed that this code is from @h0tk3y’s k-new-mpp-samples repo on GitHub. I am trying to learn how the new model works by transforming his Groovy code to Kotlin, fwiw.

[pajatopmr]

btw, I do not expect the native code to work as I’m using Gradle 5.0 (the 4.7 constraint) but I do expect k-new-mpp-samples/lib-and-app/sample-lib to build and report errors (link errors at that). That will be confirmation that I have the Groovy -> Kotlin transformation correct.

[msink]

kotlin {
    sourceSets["commonMain"].apply {
        dependencies {
            ....
        }
    }

    sourceSets.create("nativeMain").apply {
        dependencies {
            .....
        }
    }
.....

[h0tk3y]

Yeah, in Groovy, just accessing a named item as a property is equivalent to getOrCreate("..."). In the Kotlin DSL, you should either call those functions (get("...") for an existing item, create("...") for a new one, or getOrCreate("...") if in doubt) or use delegation (https://docs.gradle.org/5.0/userguide/kotlin_dsl.html#using_kotlin_delegated_properties).

[h0tk3y]

So, in Kotlin DSL, that would be something like this:

kotlin {
     sourceSets {
          // ...

          val nativeMain by creating { 
               // ...
          }

          configure(listOf(mingw, linux, mac)) {
               compilations["main"].defaultSourceSet.dependsOn(nativeMain)
          }
     }
}

[pajatopmr]

Awesome! Extremely helpful and appreciated.