Visual Basic 2015 Unleashed

Asynchronous Lambda Expressions

Methods can be asynchronous, but so can lambda expressions. To be asynchronous, a lambda must have the Async modifier and must return Task or Task(Of T), but it cannot accept ByRef arguments and cannot be an iterator function. A lambda can be asynchronous when its code uses the Await operator to wait for a Task result. An example of asynchronous lambdas is with event handlers. For instance, you might need to wait for the result of a task when an event is raised, as in the following code snippet that handles a button’s Click:

Click here to view code image

AddHandler Me.Button1.Click, Async Sub(sender, e)                                 Await DoSomeWorkAsync                             End Sub

You do not need an ...