TaskExtensions.Unwrap(Of TResult) Method (Task(Of Task(Of TResult)))
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Creates a proxy Task that represents the asynchronous operation of a Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic).
Assembly: System.Core (in System.Core.dll)
'Declaration <ExtensionAttribute> _ Public Shared Function Unwrap(Of TResult) ( _ task As Task(Of Task(Of TResult)) _ ) As Task(Of TResult)
Type Parameters
- TResult
The type of the task's result.
Parameters
- task
- Type: System.Threading.Tasks.Task(Of Task(Of TResult))
The Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic) to unwrap.
Return Value
Type: System.Threading.Tasks.Task(Of TResult)A Task that represents the asynchronous operation of the provided Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic).
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type Task(Of Task(Of TResult)). When you use instance method syntax to call this method, omit the first parameter.| Exception | Condition |
|---|---|
| ArgumentNullException | The exception that is thrown if the task argument is null. |
It is often useful to be able to return a Task from a Task, where the inner Task represents work done as part of the outer Task. However, doing so results in a Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic), which, if not dealt with carefully, could produce unexpected behavior. Unwrap solves this problem by creating a proxy Task(Of TResult) that represents the entire asynchronous operation of such a Task<Task<T>> (C#) or Task (Of Task(Of T)) (Visual Basic).