Duct-type extension methods Example 5

Example5.cs

using System.Runtime.CompilerServices;
using System.Threading.Tasks;

// Example 5: await tuple of Tasks

// Just some dummy async functions
public static Task<string> GetSomethingAsync(int number) => Task.FromResult($"Something {number}");
public static Task<int> GetAnotherThingAsync(string text) => Task.FromResult(text.Length);

// This extension method lets us await a tuple with two values
public static TaskAwaiter<(T1, T2)> GetAwaiter<T1, T2>(this (Task<T1>, Task<T2>) tasks)
=> Task.WhenAll(tasks.Item1, tasks.Item2).ContinueWith(_ => (tasks.Item1.Result, tasks.Item2.Result)).GetAwaiter();

// Now we can await the tuple directly
var (something, anotherThing) = await (GetSomethingAsync(10), GetAnotherThingAsync("something"));

// There is a bug in try.dot.net that causes the above line to fail, but it works in Visual Studio.
// You can try this line instead just to see how it works, it's exactly the same just without the syntax sugar
// var (something, anotherThing) = await System.ValueTuple.Create(GetSomethingAsync(10), GetAnotherThingAsync("something"));

Console.WriteLine(something);
Console.WriteLine(anotherThing);