可以一个任务<tresult>用于启动和存储异步方法，而无需显式调用 Run 或 StartNew 的 Task 方法？</tresult>

Question

当我从 MS 文档中查看此示例时，调用Task而不使用Run或StartNew像这样，

Coffee cup = PourCoffee();
Console.WriteLine("Coffee is ready");

Task<Egg> eggsTask = FryEggsAsync(2);
Task<Bacon> baconTask = FryBaconAsync(3);
Task<Toast> toastTask = ToastBreadAsync(2);

Toast toast = await toastTask;
ApplyButter(toast);
ApplyJam(toast);
Console.WriteLine("Toast is ready");
Juice oj = PourOJ();
Console.WriteLine("Oj is ready");

Egg eggs = await eggsTask;
Console.WriteLine("Eggs are ready");
Bacon bacon = await baconTask;
Console.WriteLine("Bacon is ready");

Console.WriteLine("Breakfast is ready!");

但是我发现的所有文档看起来你必须调用Run 、 StartNew或其他东西。

有早餐例子的文章说，

您开始一项任务并坚持代表该工作的任务 object。 在处理其结果之前，您将等待每个任务。

为什么他们不必调用 Run 或 StartNew 或其他方法？

这是我拥有的完整工作部分。 它运行，我理解它完成了什么，但我不知道他们为什么不使用Run (()=>等。

 namespace AsyncBreakfast
    {
        // These classes are intentionally empty for the purpose of this example.
        // They are simply marker classes for the purpose of demonstration,
        // contain no properties, and serve no other purpose.
        internal class Bacon { }
        internal class Coffee { }
        internal class Egg { }
        internal class Juice { }
        internal class Toast { }

        class Program
        {
            static async Task Main(string[] args)
            {
                Coffee cup = PourCoffee();
                Console.WriteLine("Coffee is ready");

                Task<Egg> eggsTask = FryEggsAsync(2);
                Task<Bacon> baconTask = FryBaconAsync(3);
                Task<Toast> toastTask = ToastBreadAsync(2);

                Toast toast = await toastTask;
                ApplyButter(toast);
                ApplyJam(toast);
                Console.WriteLine("Toast is ready");
                Juice oj = PourOJ();
                Console.WriteLine("Oj is ready");

                Egg eggs = await eggsTask;
                Console.WriteLine("Eggs are ready");
                Bacon bacon = await baconTask;
                Console.WriteLine("Bacon is ready");

                Console.WriteLine("Breakfast is ready!");

            }

        static async Task<Toast> MakeToastWithButterAndJamAsync(int number)
        {
            var toast = await ToastBreadAsync(number);
            ApplyButter(toast);
            ApplyJam(toast);

            return toast;
        }

        private static Juice PourOJ()
        {
            Console.WriteLine("Pouring orange juice");
            return new Juice();
        }

        private static void ApplyJam(Toast toast) =>
            Console.WriteLine("Putting jam on the toast");

        private static void ApplyButter(Toast toast) =>
            Console.WriteLine("Putting butter on the toast");

        private static async Task<Toast> ToastBreadAsync(int slices)
        {
            for (int slice = 0; slice < slices; slice++)
            {
                Console.WriteLine("Putting a slice of bread in the toaster");
            }
            Console.WriteLine("Start toasting...");
            await Task.Delay(3000);
            Console.WriteLine("Remove toast from toaster");

            return new Toast();
        }

        private static async Task<Bacon> FryBaconAsync(int slices)
        {
            Console.WriteLine($"putting {slices} slices of bacon in the pan");
            Console.WriteLine("cooking first side of bacon...");
            await Task.Delay(3000);
            for (int slice = 0; slice < slices; slice++)
            {
                Console.WriteLine("flipping a slice of bacon");
            }
            Console.WriteLine("cooking the second side of bacon...");
            await Task.Delay(3000);
            Console.WriteLine("Put bacon on plate");

            return new Bacon();
        }

        private static async Task<Egg> FryEggsAsync(int howMany)
        {
            Console.WriteLine("Warming the egg pan...");
            await Task.Delay(3000);
            Console.WriteLine($"cracking {howMany} eggs");
            Console.WriteLine("cooking the eggs ...");
            await Task.Delay(3000);
            Console.WriteLine("Put eggs on plate");

            return new Egg();
        }

        private static Coffee PourCoffee()
        {
            Console.WriteLine("Pouring coffee");
            return new Coffee();
        }
    }

Answer 1

为什么他们不必调用 Run 或 StartNew 或其他方法？

按照惯例，任务返回“热”； 即，已经在进行中。

Task.Run将异步方法调度到线程池线程上。 直接调用该方法将开始在当前线程上执行异步方法（正如我在博客中解释的那样）。

关于“最常见”的短语：这在 12 年前写成时可能是正确的。 我会说今天肯定不是真的。 这些天来获取任务的最常见方法是调用async方法。