如何向任务添加取消令牌？

Question

I am getting introduced to Task, and got this far:

In Main:

 Task<double> t = Task.Run(TW.DoingMegaFlops_Async);

Where in class TW:

 public async Task<double> DoingMegaFlops_Async()
 {...await ...; return 0.0;}

My concept console app builds and runs just fine. The problem is how to expand this with a Cancellation Token . I tried this:

CancellationTokenSource wtokenSource= new CancellationTokenSource();
Task.Run(TW.DoingMegaFlops_Async(wtokenSource.Token), wtokenSource.Token);

and in the TW class:

public async void DoingMegaFlops_Async(CancellationToken wtoken)
{...await...; return;}

The build error in Main is:

Cannot convert from 'void' to 'System.Action'

I have already fooled around with casting to (Action), but with no avail. Actually, I do not really understand what I am doing here, so would like to learn from the forum.

As you see from the code snippets, I already cut down on the interface of the Async method by going to a return type of void. Don't know if that actually made things easier.

Answer 1

Task.Run(TW.DoingMegaFlops_Async) is "Method Group" shorthand for Task.Run(() => TW.DoingMegaFlops_Async()) - it's allowed because you're calling a method with no parameters.

When calling a method with parameters, though, you must include it:

Task.Run(() => TW.DoingMegaFlops_Async(wtokenSource.Token), wtokenSource.Token);