In the course of writing C# code utilizing the new (for 4.5.1) Task-based asynchronous programming, I've run across a couple of places where the await keyword either is not allowed (a catch block or a property accessor) or the async keyword greatly complicates the syntax (lambda expressions). I've found myself writing this method for two different projects, and so I thought I would drop this Q&D, more-comments-than-code utility method here for others to use if you see the need.
(UPDATE: This works well in console applications; it can cause deadlocks in desktop and web apps. Test before you rely on it.)
/// <summary> /// Get the result of a task in contexts where the "await" keyword may be prohibited /// </summary> /// <typeparam name="T">The return type for the task</typeparam> /// <param name="task">The task to be awaited</param> /// <returns>The result of the task</returns> public static T TaskResult<T>(Task<T> task) { Task.WaitAll(task); return task.Result; }
And, in places where you can't do something like this…
/// <summary> /// A horribly contrived example class /// </summary> /// <remarks>Don't ever structure your POCOs this way, unless EF is handling the navigation properties</remarks> public class ExampleClass { /// <summary> /// A contrived ID to a dependent entity /// </summary> public int ForeignKeyID { get; set; } /// <summary> /// The contrived dependent entity /// </summary> public DependentEntity DependentEntity { get { // Does not compile; can't use await without async, can't mark a property as async return await Data.DependentEntities .FirstOrDefaultAsync(entity => entity.ID == ForeignKeyID); } } }
...you can instead do this in that “DependentEntity” property…
/// <summary>
/// The contrived dependent entity
/// </summary>
public DependentEntity DependentEntity
{
get
{
return UtilClass.TaskResult<DependentEntity>(Data.DependentEntities
.FirstOrDefaultAsync(entity => entity.ID == ForeignKeyID));
}
}