Passing Action<> into Async Method

Question

I understand in an async method that out and ref can not be used. But I am unclear on the consequences of using Action (or delegates). While I recognize that the value being set in the Action may not be available until after the await, are there any other problems with the below? Are their threading problems? I have googled extensively on this, but can't find clarity anywhere.

protected async Task<gPeriod> MapPeriod(string value, Action<int> setOutput)
{
    (...) //omitted code
    int x = await MyMethodAsync(value)
    setOutput(x);
    return gPeriod;  //calculation of this not shown in this example
}

There is nothing inherently wrong or dangerous about the code in the question. — Lasse V. Karlsen, Dec 06 '18 at 20:52

Wanton · Accepted Answer · 2018-12-07T05:24:22.003

2

When you always await a task, code from programmers point of view works really close to synchronous code. But when you start doing things like this

var task1 = FooAsync(setOutput);
var task2 = BarAsync(setOutput);
var result1 = await task1;
var result2 = await task2;

things start to get funny, because order they finish or threads they use is not guaranteed.

Anyway your code is fine.

edited Dec 07 '18 at 05:24

answered Dec 06 '18 at 21:24

Wanton

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Passing Action<> into Async Method

1 Answers1