vala Async and Yield Yield from an Asynchronous Function
Example
In order to chain asynchronous operations and avoid a callback hell, Vala supports the yield statement.
Used with an asynchronous invocation, it will pause the current coroutine until the call is completed and extract the result.
Used alone, yield pause the current coroutine until it's being woken up by invoking its source callback.
public async int foo_async () {
yield; // pause the coroutine
Timeout.add_seconds (5, bar_async.callback); // wakeup in 5 seconds
return ret + 10;
}
public async int bar_async () {
var ret = yield foo_async ();
}
