| Feature |
What It Does |
| XML Support |
Provides native support for XML literals and XML expressions.
See this article for more details. |
| Coalesce Operator |
The Coalesce operator takes two arguments. If the first is null, then the second argument is returned, otherwise the first argument is returned. Its syntax looks like this:
value = If(nullable, defaultValueIfNull)
For more details, see "Load Up with VB's Operators," August 2007 |
| Ternary Operator |
A ternary operator is an inline If operator, as in this example:
value = If(BooleanExpression, ValueIfTrue, ValueIfFalse)
For more details, see "Load Up With VB's Operators," August 2007 |
| Nullable Types |
Nullable types can be specified by using a ? modifier:
Dim x As Integer? 'same as Nullable(Of Integer)
VB 2008 also includes support for operators on nullable types.
For more details, see the sidebar, "6 Tips for Nullable Types," in the On VB column, "Drill Down on Anonymous Types," October 2007 |
| Type Inference |
Allows the variable's type to be inferred by the value assigned to it. The declaration (variable defined with the Dim keyword) must be accompanied with an assignment statement ( = statement). You can turn type inference on/off with the Option Infer statement. The syntax looks like this:
Dim name = "Bill"
For more details, see the question about inferred typing in Ask Kathleen |
| Object Initializers |
Use the With statement to set properties on an object as part of a constructor statement:
Dim cust as New Customer() With {.Name = "Bill"}
For more details, see the On VB column, "Drill Down on Anonymous Types," October 2007 |
| Anonymous Types |
A type definition is created for you with properties with their types determined by the values you assign. VB has both mutable and immutable anonymous types: an immutable property is declared with the Key keyword:
Dim product = New () With {.Price = 9.99, Key .Name = "widget"}
For more details, see the On VB column, "Drill Down on Anonymous Types," October 2007
|
| Extension Methods |
You apply the Extension attribute to methods declared in a module. These methods can then be used as if they are members of the first parameter's type. LINQ libraries contain extension methods on IEnumerable and IQueriable.
For more details, see the On VB column, "Beautify Your Code with Extensions," May 2007 |
| LINQ |
Language Integrated Query lets you use a SQL-like syntax in VB:
im bills = From c in Customers Where c.FirstName = "Bill"
For more details, see the On VB column, "LINQ Changes How You Will Program," September 2007 |
| Lambda expressions |
Lambda expressions are inline functions. These are currently limited to a single statement.
For more details, see the On VB column, "LINQ Changes How You Will Program," September 2007 |
| Expression Trees |
Statements are compiled as expression trees, allowing interpretation and translation of the expression. A typical usage is an expression in a LINQ query is compiled to an expression tree, then at runtime translated to TSQL.
For more details, see the On VB column, "LINQ Changes How You Will Program," September 2007 |
| Partial methods |
Partial methods are designed for code generation. An empty Private method declaration (Sub) is included in the generated file and marked as Partial. You can then implement your own method with the same name, thus plugging into the generated code. |
| Relaxed Delegates |
You can use method signatures for event handlers where the parameter types are wider than the event specifies. This is most useful when you want to use the one handler for many different kinds of events in a Windows.Forms application. You can also omit all the parameters for
the handler. |
| Friend Assemblies |
Include the InternalsVisibileTo attribute in an assembly to let another assembly access Friend scoped members.
<Assembly: InternalsVisibleTo("FriendAssembliesB")> |