C++/WinRT envy: Bringing thread switching tasks to C# (WPF and WinForms edition)

Raymond Chen March 29, 2019 Mar 29, 2019 03/29/19

Last time, we brought Thread­Switcher.Resume­Foreground­Async and Thread­Switcher.Resume­Background­Async to C# for UWP. Today, we'll do the same for WPF and Windows Forms. It'll be easier the second and third times through because we already learned how to structure the implementation. It's just the minor details that...

C++/WinRT envy: Bringing thread switching tasks to C# (UWP edition)

Raymond Chen March 28, 2019 Mar 28, 2019 03/28/19

Last time, we developed a Run­Task­Async method to try to make it easier to switch threads in a task, but we saw that while it simplified some operations, it was still cumbersome because of the difficulty of sharing state between the main method and the async lambdas that it kicked off to other threads. Let's fix that by stealing an ...

How do I wait for the completion of the delegate I passed to Core­Dispatcher.Run­Async and Thread­Pool.Run­Async?

Raymond Chen March 27, 2019 Mar 27, 2019 03/27/19

As we saw last time, The the Core­Dispatcher::Run­Async and Thread­Pool::Run­Async methods complete when the delegate returns, which is not the same as when the delegate completes. How can you wait until the delegate completes? We'll have to track the delegate completion ourselves. One way is to signal the completion with a ...

When do Core­Dispatcher.Run­Async and Thread­Pool.Run­Async actions complete?

Raymond Chen March 26, 2019 Mar 26, 2019 03/26/19

The Core­Dispatcher::Run­Async and Thread­Pool::Run­Async methods take a delegate and schedule it to be invoked on the dispatcher thread or on a thread pool thread. These methods return an IAsync­Action, but when does that action complete? When dealing with asynchronous methods, there are two ways of talking about the ...

Turning anything into a fire-and-forget coroutine

Raymond Chen March 22, 2019 Mar 22, 2019 03/22/19

Last time, we wrote a helper function for converting an awaitable into a winrt::fire_and_forget, as well as another helper function that takes a lambda that returns an awaitable, and which invokes the lambmda as a winrt::fire_and_forget. After I wrote the two functions, I wondered if I could unify them. Mostly because I wanted to use the same...

Expressing fire-and-forget coroutines more explicitly, -or- How to turn any coroutine into fire-and-forget

Raymond Chen March 21, 2019 Mar 21, 2019 03/21/19

Last time, we looked at how to mark a coroutine as fire-and-forget, meaning that the caller does not get any information about when the coroutine completes. This is fine as far as it goes, but it may not be what you want. Fire-and-forget-ness is frequently a property of the call site, not the function itself. A particular coroutine could be ...

winrt::fire_and_forget was too forgetful

Raymond Chen March 20, 2019 Mar 20, 2019 03/20/19

C++/WinRT provides a handy helper class called winrt::fire_and_forget. It lets you specify that nobody is going to observe the result of the coroutine. This is handy because it lets you tell the compiler that the lack of observation is intentional, so it won't generate a warning. The OnClick function calls Do­Something, which does a bunch...