Can someone please explain me why i can use `runBl...

# multiplatform

[Boris Dudelsack]

Can someone please explain me why i can use runBlocking in linuxMain and in macosMain but i cannot use it wether in my own source set nativeMain nor in commonMain. Do i need add some sort of configuration to the source set?

plugins {
    kotlin("multiplatform")
}

kotlin {
    linuxX64("linux") {
        binaries {
            executable()
        }
    }

    macosX64("macos") {
        binaries {
            executable()
        }
    }

    sourceSets {
        val commonMain by getting {
            dependencies {
                implementation(kotlin("stdlib-common"))

                implementation ("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.4.1-native-mt")
            }
        }

        val nativeMain by creating {
            dependsOn(commonMain)
        }

        val macosMain by getting {
            dependsOn(nativeMain)
        }

        val linuxMain by getting {
            dependsOn(nativeMain)
        }

    }
}

[Boris Dudelsack]

[Sam]

runBlocking is not defined in ‘common’ because it doesn’t have implementations in all targets that Kotlin supports, namely Javascript. You can use expect/actual to define it in your common source set. The actual part on each platform can just be an alias.

[Marc Knaup]

Shouldn’t commonizer make it available to nativeMain? 🤔

[Boris Dudelsack]

Ok, i've managed to use runBlocking in commonMain with following:
commonMain

expect fun <T> runBlocking(context: CoroutineContext, block: suspend CoroutineScope.() -> T): T

linuxMain, macosMain

import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.runBlocking as runBlockingNative
import kotlin.coroutines.CoroutineContext

actual fun <T> runBlocking(context: CoroutineContext, block: suspend CoroutineScope.() -> T): T = runBlockingNative(context, block)

But why cannot i just define/use it in nativeMain?

[russhwolf]

You can use it, but the IDE doesn't resolve it. It'll still build from gradle. In theory hmpp/commonizer should help here but I've never gotten it to work for runBlocking.

[Michal Klimczak]

Whats the reason for ide not resolving these classes when they still build fine? I have this problem ina few places in my project and can't fix it. Not a big deal but annoyance

[Animesh Sahu]

Enable granular metadata if you don't target js

[Michal Klimczak]

You mean kotlin.mpp.enableGranularSourceSetsMetadata=true? I have it enabled, but the problem persists

[Animesh Sahu]

Should work, if you don't have js target

[Michal Klimczak]

I don't have js.
Right now it seems to work fine in the shared module (the one compiled for swift) but is messed up in another module.

• module1 (multiplatform)
• module2 (jvm, depends on module1)
• shared (multiplatform, depends on module1 and kapt-module2)
• settings.gradle for the whole project has the enableGranularEtc=true
And in module2 Android Studio says Unresolved reference for classes from module1. Everything is fine in shared

[Artyom Degtyarev [JB]]

The commonizer cannot deal with this case as it’s capable of sharing only Kotlin/Native platform libraries at the moment(see README.md). The reason why runBlocking is not available from common code is that it is not supported for the js target, as already mentioned. Expect/Actual mechanism use seems to be the best option. Related issues: https://github.com/Kotlin/kotlinx.coroutines/issues/195, https://github.com/Kotlin/kotlinx.coroutines/issues/1039, https://youtrack.jetbrains.com/issue/KT-29403

[Marc Knaup]

@Artyom Degtyarev [JB] nativeMain mentioned before only consists of native targets.

https://kotlinlang.slack.com/archives/C3PQML5NU/p1610477636230700

[Artyom Degtyarev [JB]]

Hmm. If the library was published as described in the documentation, this should work correctly, with the hierarchical project structure enabled. Thank you for noticing, @Marc Knaup 🙂
To be honest, I haven’t checked it locally. If the problem seems reproducible, it would be nice to report it on the youtrack with a project to play with.

[Boris Dudelsack]

Sorry, i haven't had the granular Metadata enabled. Adding kotlin.mpp.enableGranularSourceSetsMetadata=true to the gradle.properties seems to help.

[Animesh Sahu]

Yeah! That's what I've said, it runs commonizer to have all the common things available in commonMain, and so on (if you have a common module in between the source tree)

[Animesh Sahu]

If you add js as target, you'd not get it on commonMain, but on nativeMain :)