How can out string values with Task function in C#

Question

How can out string values with Task function in C# i need fix this code to return Task with out string values

public Task<bool> DelUserTemp(string UserID, int FingerIndex ,out string result)
{
    return Task.Run(() =>
    {
        if (true)
        {
            result = "done";
            return true;
        }
        else
        {
            result = "error";
            return false;
        }
    });
}

How would you see it working if you could? Imagine you store the task of `DelUserTemp`, do something with `result` before it's assigned, and then `await` the task. Use a custom return object, or a `ValueTuple`. — ProgrammingLlama, Feb 14 '19 at 07:26
Typical example why providing too many options confuses learners. `Task` `out` `bla bla`. — Sarvesh Mishra, Feb 14 '19 at 07:51
Having a method that just `Task.Run`s some other code is usually a bad design - just provide a method that runs synchronously and let the *caller* decide whether to use it directly or to `Task.Run` it. (Exception: CPU heavy work that shouldn't run on the calling thread) — Damien_The_Unbeliever, Feb 14 '19 at 09:38

score 6 · Answer 1 · edited Feb 14 '19 at 09:30

6

An alternative to using ref/out would be to return C# 7.0 tuples instead.

public Task<(bool Worked, string Result)> DelUserTemp(string UserID, int FingerIndex)
{
    return Task.Run(() =>
    {
        if (true)
        {
            return (true, "done");
        }
        else
        {
            return (false, "error");
        }
    });
}

edited Feb 14 '19 at 09:30

TanvirArjel

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answered Feb 14 '19 at 08:10

Magnus

45,362
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score 1 · Answer 2 · answered Feb 14 '19 at 08:14

Yet another example is to create class and return it:

public class MyResult
{
    public bool Succeeded {get;}
    public string ErrorMessage {get;}

    public MyResult(bool succeeded, string errorMessage)
    {
        Succeeded = succeeded;
        ErrorMessage = errorMessage;
    }
}

public Task<MyResult> DelUserTemp(string UserID, int FingerIndex ,out string result)
{
    return Task.Run(() =>
    {
        if (true)
        {
            return new MyResult(true, "done");
        }
        else
        {
            return new MyResult(false, "error");
        }
    });
}

How can out string values with Task function in C#

2 Answers2