async methods are different than normal methods. Whatever you return from async methods are wrapped in a Task. If you return no value(void) it will be wrapped in Task, If you return int it will be wrapped in Task<int> and so on. If your async method needs to return int you’d mark the return type … Read more
You’re effectively using promises inside the promise constructor executor function, so this the Promise constructor anti-pattern. Your code is a good example of the main risk: not propagating all errors safely. Read why there. In addition, the use of async/await can make the same traps even more surprising. Compare: let p = new Promise(resolve => … Read more
The async equivalent of Action<T> is Func<T, Task>, so I believe this is what you’re looking for: public async Task<T> DoSomethingAsync<T>(Func<T, Task> resultBody) where T : Result, new() { T result = new T(); await resultBody(result); return result; }
I found this question very interesting, especially since I’m using async everywhere with Ado.Net and EF 6. I was hoping someone to give an explanation for this question, but it doesn’t happened. So I tried to reproduce this problem on my side. I hope some of you will find this interesting. First good news : … Read more
I’m wondering if there is any way to get a value from a Promise or wait (block/sleep) until it has resolved, similar to .NET’s IAsyncResult.WaitHandle.WaitOne(). I know JavaScript is single-threaded, but I’m hoping that doesn’t mean that a function can’t yield. The current generation of Javascript in browsers does not have a wait() or sleep() … Read more
I don’t understand how any of the proposed approaches that wrap JDBC calls in Actors, executors or anything else can help here – can someone clarify. Surely the basic problem is that the JDBC operations block on socket IO. When it does this it blocks the Thread its running on – end of story. Whatever … Read more
To answer your questions, I will provide 3 different solutions to the same problem. Case 1: just normal Python import time def sleep(): print(f’Time: {time.time() – start:.2f}’) time.sleep(1) def sum(name, numbers): total = 0 for number in numbers: print(f’Task {name}: Computing {total}+{number}’) sleep() total += number print(f’Task {name}: Sum = {total}\n’) start = time.time() tasks … Read more
You can call a function after the state value has updated: this.setState({foo: ‘bar’}, () => { // Do something here. }); Also, if you have lots of states to update at once, group them all within the same setState: Instead of: this.setState({foo: “one”}, () => { this.setState({bar: “two”}); }); Just do this: this.setState({ foo: “one”, … Read more
The for loop runs immediately to completion while all your asynchronous operations are started. When they complete some time in the future and call their callbacks, the value of your loop index variable i will be at its last value for all the callbacks. This is because the for loop does not wait for an … Read more
The most important thing to know about async and await is that await doesn’t wait for the associated call to complete. What await does is to return the result of the operation immediately and synchronously if the operation has already completed or, if it hasn’t, to schedule a continuation to execute the remainder of the … Read more