返回任务<bool>即刻 [英] Return Task&lt;bool&gt; instantly

问题描述

我有一个任务列表，我想等待.我在等

I have a list of tasks, which i'd like to wait for. I'm waiting like

    await TaskEx.WhenAll(MyViewModel.GetListOfTasks().ToArray());

MyViewModel.GetListOfTasks() 返回任务列表:

MyViewModel.GetListOfTasks() returns List of Task:

    var tasksList = new List<Task>();
    foreach (var item in Items)
    {                
        tasksList.Add(item.MyTask());
    }

现在，我想返回虚拟任务，该任务将立即完成.但是，TaskEx.WhenAll 会永远等待它:

Now, i'd like to return dummy task, which would be done immediately. However, TaskEx.WhenAll would wait it forever:

    public Task<bool> MyTask()
    {
        return new Task<bool>(() => false);
    }

我如何返回任务，它会立即完成?

How can i return Task, which would be finished instantly?

推荐答案

在 .NET 4.5 中，您可以使用 FromResult 立即返回任务的结果.

in .NET 4.5 you can use FromResult to immediately return a result for your task.

public Task<bool> MyTask()
{
    return TaskEx.FromResult(false);
}

http://msdn.microsoft.com/en-us/library/hh228607%28v=vs.110%29.aspx

对于 Windows Phone 8.1 及更高版本，API已合并以与其他平台保持一致:

For Windows Phone 8.1 and higher, the API has been merged to be consistent with other platforms:

public Task<bool> MyTask()
{
    return Task.FromResult(false);
}

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