Highlights of Visual Basic 14: Null‑Safety, Interpolation, and Other New Language Features

Visual Basic 14 (VB.NET) jumps from version 12 to 14, introducing many new language features that simplify development and bring parity with C#.

Null support : The null‑conditional operator ?. allows safe navigation of potentially null references. For example:

If customer.PrimaryResidence Is Not Nothing AndAlso customer.PrimaryResidence.Garage IsNot Nothing AndAlso property.PrimaryResidence.Garage.Cars = 2 Then Print("Two Car Garage")

can be reduced to:

If property.PrimaryResidence?.Garage?.Cars = 2 Then Print("Two Car Garage")

The operator can also be combined with If to provide default values:

Dim numberOfCarPorts = If(property.PrimaryResidence?.Garage?.Cars, 0)

Other languages such as Objective‑C support similar null‑handling semantics.

Metaprogramming : VB 12 introduced CallerNameAttribute and the NameOf operator, enabling compile‑time retrieval of member names. Example:

Function Lookup(name As String) As Customer
    If name Is Nothing Then Throw New ArgumentNullException(NameOf(name))
End Function

String interpolation : The $"…" syntax replaces String.Format and reduces counting errors. Example:

Dim message = $"Hello {name}, your amount due is {total:C2}"

When constructing URLs, developers should still encode parameters:

Dim requestUrl = $"http://{server}/customer?name={UrlEncode(customerName)}"

FormattedString object : Interpolated strings may be represented by a FormattedString object that implements IFormattable . Its ToString method forwards to String.Format with a supplied IFormatProvider .

string IFormattable.ToString(string ignored, IFormatProvider formatProvider)
{
    return String.Format(formatProvider, format, args);
}

Multi‑line strings : VB now supports line‑breaks without explicit quotes; the compiler chooses the appropriate line‑separator (vbCrLf, vbCr, vbLf) automatically.

Readonly auto‑properties : Auto‑properties can be declared ReadOnly and initialized either at declaration or in a constructor. The compiler uses copy‑in/copy‑out semantics when such properties are passed by reference.

Public ReadOnly FirstName As String = "Anonymous"
Public ReadOnly LastName As String
Public Sub New(firstName As String, lastName As String)
    Me.FirstName = firstName
    Me.LastName = lastName
End Sub

Comments : Inline comments can now be placed at the end of each line in a multi‑line statement.

Dim emailList =
    From c In Customers
    Where c.IsActive 'ignore inactive customers
    And Not c.DoNotEmail 'we don’t need another spam violation
    Select c.FullName, c.EmailAddress

Structs : Structs now support parameterless constructors, though their execution timing varies depending on how the struct is instantiated.

Data literals : Date literals follow ISO‑8601 format (e.g., #2005-4-3# ) instead of ambiguous US‑style formats.

Interop with C# : The Overrides modifier now implicitly includes Overloads , simplifying cross‑language library usage.

Interface ambiguity : VB disallows ambiguous interface inheritance that C# permits, reducing cases where a call cannot be resolved.

Namespace resolution : VB 14 can resolve ambiguous namespaces such as Threading , offering both System.Threading and System.Windows.Threading in IntelliSense.

TypeOf and IsNot : The IsNot operator can now be used in TypeOf … IsNot … expressions.

If TypeOf sender IsNot Button Then

Preprocessor directives : Two improvements include better region handling and the ability to disable/enable specific warnings.

#Disable Warning BC42356 'suppress warning about no awaits in this method
#Enable Warning BC42356

XML documentation validation : The compiler now validates XML doc comments, checking parameter references and generic type handling in cref tags.

Partial modules and interfaces : Modules and interface declarations can now be marked Partial , aiding code generation and cross‑platform sharing.

(Source: InfoQ)