withContext

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

Calls the specified suspending block with a given coroutine context, suspends until it completes, and returns the result.

The resulting context for the block is derived by merging the current coroutineContext with the specified context using coroutineContext + context (see CoroutineContext.plus). This suspending function is cancellable. It immediately checks for cancellation of the resulting context and throws CancellationException if it is not active.

This function uses dispatcher from the new context, shifting execution of the block into the different thread if a new dispatcher is specified, and back to the original dispatcher when it completes. Note that the result of withContext invocation is dispatched into the original context in a cancellable way with a prompt cancellation guarantee, which means that if the original coroutineContext, in which withContext was invoked, is cancelled by the time its dispatcher starts to execute the code, it discards the result of withContext and throws CancellationException.

The cancellation behaviour described above is enabled if and only if the dispatcher is being changed. For example, when using withContext(NonCancellable) { ... } there is no change in dispatcher and this call will not be cancelled neither on entry to the block inside withContext nor on exit from it.

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