Here is a very simple example showing how to find all matching items from a generic List(of T) using lambda functions in VB.NET.

Dim MatchedItems As List(Of User) = Members.FindAll(Function(u As User) (u.Age<18))

Here the FindAll() function is accepting a Predicate(Of User) Delegate. And we can pass lambda functions where ever a delegate to a function is accepted. The FindAll() method calls our lambda function for each item in the list for deciding whether the item matches our requirements. If it does (our Predicate(Of T) returns True) the Item is included in the returned list.

Another nice thing is that this feature (lambda functions) are supported even in projects where the target .NET framework version is 2.0. So, we can use these lambda functions in our .NET 2.0 application as wel.

Creating registry keys and keeping it up to date is now very easy in vb.net using the class My.Computer.Registry. The SetValue() method will create the specified keys if it does not exists and set it's value to the value provided. It is certainly a helpful method as now we do not have to worry about creating keys if doesn't exists etc.

A simple example follows:

My.Computer.Registry.SetValue("hkey_classes_root\txtfile\Shell\Process\Command", "", """" & Application.ExecutablePath & """ ""%1""")

This will create a item named "Process" in the context menu for all the text files which will be shown when user right-clicks on any of the text files in the windows explorer. And choosing "Process" from the context menu will start your application with the name of the file on which the user right-clicked as the command-line argument to your program.

The My.* namespaces are in the Microsoft.VisualBasic.Dll which is automatically referenced in any VB project.

Happy hacking!