使用 Dispatcher.RunAsync() 启动任务并立即返回的正确方法是什么？

Question

Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
    //do something
});

The above code causes Compiler Warning (level 1) CS4014 :

Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the await operator to the result of the call.

The behavior is exactly what I want: start the task and let it run in a separate thread and return immediately.

I can make the warning go away by changing the code to the following:

var v = Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
    //do something
}); 

I think "var v" is redundant. Why is the compiler happy with this redundancy?

Could anyone shed some light on this?

Answer 1

Why is the compiler happy with this redundancy?

Because it uses a very simple heuristic. It doesn't do an in-depth analysis of the entire program to determine if every code path (or any code path) observes the results of the Task . The warning is only triggered by the return value of the Task-returning method (in an async method) not ever being stored or accessed. The main idea here is to prevent someone from calling a method that they don't even realize is asynchronous and unintentionally ignoring the result. Intentionally ignoring the result isn't something it's trying to prevent.