[英]Getting return value from Task.Run
我有以下代码:
public static async Task<string> Start(IProgress<ProcessTaskAsyncExProgress> progress)
{
const int total = 10;
for (var i = 0; i <= total; i++)
{
await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture)));
if (progress != null)
{
var args = new ProcessTaskAsyncExProgress
{
ProgressPercentage = (int)(i / (double)total * 100.0),
Text = "processing " + i
};
progress.Report(args);
}
}
return "Done";
}
private static string RunLongTask(string taskName)
{
Task.Delay(300);
return taskName + "Completed!";
}
如何从这一行RunLongTask
的字符串值: await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture)));
?
我试过了:
var val = await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture))).Result;
但是我收到一条错误消息,说“字符串不可等待”。
从最后删除Result
。 当您await
您将从可等待的方法中获得Result
。
var val = await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture)));
这不是对旧问题的直接回答,而是对其他人的搜索:
“通常”您不应该这样做,但有时您需要匹配库 API,以便您可以使用如下包装函数:
private async Task<string> WrapSomeMethod(string someParam)
{
//adding .ConfigureAwait(false) may NOT be what you want but google it.
return await Task.Run(() => SomeObj.SomeMethodAsync(someParam)).ConfigureAwait(false);
}
然后用 .Result 调用它,如下所示:
string blah = WrapSomeMethod(someParam).Result;
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