coroutineScope

Creates a CoroutineScope and calls the specified suspend block with this scope. The provided scope inherits its coroutineContext from the outer scope, using the Job from that context as the parent for a new Job.

This function is designed for concurrent decomposition of work. When any child coroutine in this scope fails, this scope fails, cancelling all the other children (for a different behavior, see supervisorScope). This function returns as soon as the given block and all its child coroutines are completed. A usage of a scope looks like this:

suspend fun showSomeData() = coroutineScope {
    val data = async(Dispatchers.IO) { // <- extension on current scope
     ... load some UI data for the Main thread ...
    }

    withContext(Dispatchers.Main) {
        doSomeWork()
        val result = data.await()
        display(result)
    }
}

The scope in this example has the following semantics:

1. showSomeData returns as soon as the data is loaded and displayed in the UI.

2. If doSomeWork throws an exception, then the async task is cancelled and showSomeData rethrows that exception.

3. If the outer scope of showSomeData is cancelled, both started async and withContext blocks are cancelled.

4. If the async block fails, withContext will be cancelled.

The method may throw a CancellationException if the current job was cancelled externally, rethrow the exception thrown by block, or throw an unhandled Throwable if there is one (for example, from a crashed coroutine that was started with launch in this scope).