/// <summary>
/// Returns a task that can be blocked against until a specific property changes.
/// The property or properties should be marked with <see cref="BlockingPropertyAttribute"/> otherwise a completed task will be returned immediately.
/// </summary>
/// <param name="self">Class instance that contains the properties</param>
/// <returns>Task that can be awaited until the decorated properties change</returns>
public static Task <bool> BlockUntil(this INotifyPropertyChanged self)
{
TaskCompletionSource <bool> completionSource;
if (self.TaskCompleted(out completionSource))
{
// The task is already finished
return(Task.FromResult(true));
}
completionSource = new TaskCompletionSource <bool>();
if (!CompletionSources.ContainsKey(self))
{
CompletionSources.Add(self, completionSource);
}
self.PropertyChanged += SelfOnPropertyChanged;
return(completionSource.Task);
}
