async Task Main() + GUI

Jasper

Hi,
I just noticed the very nice feature with async Task Main.
However, the following piece of code acts a little unexpected.
//[STAThread] async Task Main() { await Task.Delay(TimeSpan.FromSeconds(1));// .ConfigureAwait(true); new Button(){Content = "A"}.Dump(); }
I would expect it to return to the execution context of the ui thread.
In comparison, this works:
async Task Main() { var disp = Dispatcher.CurrentDispatcher; await Task.Delay(TimeSpan.FromSeconds(1));//.ConfigureAwait(true); disp.Invoke(() => { new Button() {Content = "A"}.Dump(); }); }
Also is there a way to get the ui dispatcher so that one could dispatch work to the ui thread of the query? I noticed it is possible to just get the current dispatcher at the top of the query but that feels a little bit off for larger queries.

Thanks in advance.

JoeAlbahari

You need to ensure that a synchronization context is created before the first await.

You can do this by dumping a UI control before the first await, or by putting the following code at the start of your query:

Util.CreateSynchronizationContext();

Jasper

Ah, I see.
Thanks again.

benoit

Is it possible to make it work with MTA threads?

JoeAlbahari

You can make LINQPad use MTA threads in Edit | Preferences > Advanced, with the usual provisos of MTA threads.

benoit

I was asking if it possible to have async code with MTA threads and UI being properly dumped/displayed? Or if I need UI from async code then I need to use STA threads?

JoeAlbahari

If you need a UI, you must stick with STA threads. Keep in mind that your choice of STA/MTA for queries applies only to the main query thread. Worker threads and pooled threads will still be MTA.

In other words, the following expression always returns MTA:

await Task.Run (() => Thread.CurrentThread.GetApartmentState())

benoit

Thanks for clarification.