Although it is theoretically possible to use async/await during object resolution, you should consider the following constraints: Constructors can’t be asynchronous, and Construction of object graphs should be simple, reliable and fast Because of these constraints, it’s best to postpone everything that involves I/O until after the object graph has been constructed. So instead of … Read more
I have trouble understanding how this actually helps more than just storing the results. When a method is marked with the async modifier, the compiler will automatically transform the underlying method into a state-machine, as Stephan demonstrates in previous slides. This means that the use of the first method will always trigger a creation of … Read more
This is a great question which really isn’t explained well in most texts about C# and async. I searched for this for ages thinking I could and should maybe be implementing my own async I/O methods. If a method/library I was using didn’t have async methods I thought I should somehow wrap these functions in … Read more
I’ve used ContinueWith which can work if you have one or multiple Tasks running. example: public async Task<T> MyAsyncFun() { T value = await … return value; } MyAsyncFun().ContinueWith(… https://msdn.microsoft.com/en-us/library/dd270696(v=vs.110).aspx
Preface (you probably know this!): await is syntactic sugar for using promise callbacks. (Really, really, really good sugar.) An async function is a function where the JavaScript engine builds the promise chains and such for you. Answer: The relevant thing isn’t so much whether the promise is settled, but whether the promise callbacks (and the … Read more
should I make absolutely all my methods initially async even if I’m not planning to call anything async inside? This design problem with async is essentially the same as the problem with IDisposable. That is, interfaces have to predict their implementations. And this is going to be messy, no matter what you do. In my … Read more
Async/Await only works on functions that return (and resolve) a promise. The following example will write to the console after 3 seconds, and then continue on. // Tell the browser that this function is asynchronous async function myFunc() { // Await for the promise to resolve await new Promise((resolve) => { setTimeout(() => { // … Read more
To prevent data races you must use synchronized access to variables from concurrent operations and the compiler doesn’t allow you to change your array directly. To avoid the issue you can implement isolated access to your data with an actor instance e.g.: actor Store { var reviewIds: [Int] = [] func append(ids: [Int]) { reviewIds.append(contentsOf: … Read more
when async is encountered, then the function is sent to the event loop and the main thread can continue working. This is close, but not quite right. In Javascript, execution won’t stop until the callstack has been emptied – the await keyword will suspend the execution of a particular function until an event triggers, and … Read more
If a third-party library is not compatible with async/await then obviously you can’t use it easily. There are two cases: Let’s say that the function in the library is asynchronous and it gives you a callback, e.g. def fn(…, clb): … So you can do: def on_result(…): … fn(…, on_result) In that case you can … Read more