android - 对Kotlin协程感到困惑

Question

这没有编译错误:

suspend fun test() {
    runBlocking {

    }
}

这有一个编译错误:

suspend fun test() {
    launch {

    }
}

Unresolved reference. None of the following candidates is applicable because of receiver type mismatch: public fun CoroutineScope.launch(context: CoroutineContext = ..., start: CoroutineStart = ..., block: suspend CoroutineScope.() -> Unit): Job defined in kotlinx.coroutines

我不太明白是什么问题...

Answer 1

在某些Coroutines are launched的上下文中，使用launch协程生成器生成CoroutineScope:

fun test() = CoroutineScope(Dispatchers.Main).launch {
}

launch-是 CoroutineScope对象上的 extension function，它是 defined，如下所示:

public fun CoroutineScope.launch(...): Job {}

runBlocking-不是扩展函数，因此可以将其称为常规函数，它是 defined，如下所示:

public fun <T> runBlocking(...): T {}