1. Microsoft Visual Basic 2005: New Language Features
Stan Schultes
Architect, Developer, Author
Microsoft MVP Visual Basic

2. Agenda Major Additions: New Language Statements: Operator Overloading
My, XML Comments, Generics
New Language Statements:
Using, Continue, TryCast, Global, IsNot
Operator Overloading
Conversion Operators, Unsigned Types
Other Features:
Property Accessor Accessibility
Custom Event Accessors
Partial Types
Application Level Events
Compiler Warnings
Explicit Array Bounds
Form Default Instances
Refactoring

3. My Hierarchy “Speed Dial” & Dynamic Types
— Application title, version, logs, description, …
— Registry, audio, file system, …
— User name, group, domain, …
— Access resources for the application: icons, images,…
— User and application settings
— Collection of project forms
— Collection of Web services referenced in project

4. My.Application My.Application is designed to:
Make application-related properties more accessible
Allow commonly referenced services and classes to be enabled easily
Provide a more manageable framework for application startup and shutdown

5. My.Computer
My.Computer provides straightforward access to the host computer’s properties and hardware resources, allowing devices to be enabled easily and their services integrated seamlessly into applications

6. My.User
My.User provides access to properties for the currently logged-on user of the application.
Also allows the developer to implement IPrincipal and IIdentity to interface with other authentication schemes such as SQL databases.

7. My (Dynamic Types) Provided Automatically by Compiler
Application level version of “Me”
My.Resources
PictureBox1.Image = My.Resources.Logo
My.Settings
My.Settings.FormLocation = Me.Location
My.Forms
My.Forms.Form1.Show
My.WebServices
My.WebServices.MSDN.Search(“VB”)

8. My.Resources
Strongly-typed interface to resources added with the Resources Editor
Manipulate image & media files
Manage strings in resource files by culture
'MVPLogo.png added with Resources Editor
Button1.BackgroundImage = My.Resources.MVPLogo

9. Settings Architecture
Settings Base
Application Settings Base
Windows App Settings
My Settings
Provider Interface
Local Settings
Remote
Custom
SQL
Access
Custom

10. Settings in Action App settings User Settings Myapp.exe.config
<applicationSettings> …
</applicationSettings>
fred.config
ethel.config
gladys.config
<userSettings> …
</userSettings>

11. Settings in Action Load Save Handling events for validation
My.Settings.WorkOffline = True ‘ Settings automatically loaded on first access
Load
My.Settings.WorkOffline = True My.Settings.Save()
Save
Private Sub Settings_SettingChanging(ByVal sender As Object, _
ByVal e As SettingsArg) Handles MyBase.SettingChanging
If e.SettingName = “DataCache” Then
If Not My.Computer.FileSystem.FileExists(e.Setting.Value)Then
‘ Cancel event
End If
End Sub
Handling events for validation

12. My.Forms My.WebServices
Dynamically generated by the compiler
Default form instance is back:
My.Forms.Form1.Show
Web service proxy goop handled for you:
Dim CompanyDataSet As New ServiceDataSet = My.WebServices.CompanyData.LoadDataSet

13. XML Comments No More C# Envy
Type three single-quotes above a class, field, method or enum to insert an XML Comment template.
The template is like a form you can tab through and enter details.
Intellisense immediately includes comment strings you enter.
Considered by the compiler an integral part of your code (colorizes & syntax checks).
XML documentation file automatically created when you build the project.

14. Generics Specify Type at Declaration Time
New namespace:
System.Collections.Generic
Create the equivalent of a custom collection in one line of code
Huge time saver when handling collections of specific types.
Create your own generic types

15. Generics (Example) Dim intList As New List(Of Integer)
Public Class List
Private elements() As Object
Private mCount As Integer
Public Sub Add(element As Object)
If (mCount = elements.Length) Then _
Resize(mCount * 2)
mCount += 1
elements(mCount) = element
End Sub
Default Public Property Indexer(index As Integer) As Object
Get : Return elements(index) : End Get
Set : elements(index) = value : End Set
End Property
Public Property Count() As Integer
Get : Return mCount : End Get
End Class
Public Class List(Of ItemType)
Private elements() As ItemType
Private count As Integer
Public Sub Add(element As ItemType)
If (count = elements.Length) Then _
Resize(count * 2)
count += 1
elements(count) = element
End Sub
Default Public Property Indexer(index As Integer) As ItemType
Get : Return elements(index) : End Get
Set : elements(index) = value : End Set
End Property
Public Property Count As Integer
Get : Return count : End Get
End Class
Dim intList As New List(Of Integer)
intList.Add(1) ‘ No boxing
intList.Add(2) ‘ No boxing
intList.Add("Three") ‘ Compile-time error
Dim i As Integer = intList(0) ‘ No cast
Dim intList As New ArrayList()
intList.Add(1) ‘ Argument is boxed
intList.Add(2) ‘ Argument is boxed
intList.Add("Three") ‘ Should be an error
Dim i As Integer = CInt(intList(0)) ‘ Cast

16. Generics (Specifics) Compile-time checking Better performance
Eliminates runtime errors
Better performance
No casting or boxing overhead
Code re-use
Easy to create strongly typed collections
Common data structures in framework
Dictionary, HashTable, List, Stack, etc.

17. New Language Statements Making the Language Complete
IsNot – logical counterpart to Is statement
Using – acquire, execute, release resources
Continue – skips to next iteration of loop
TryCast – returns Nothing if cast fails
Global – access to root (empty) namespace

18. IsNot Logical counterpart to Is
Clearer way of determining if an object has a value or is equivalent to another object
'prior VB syntax
If Not prd Is Nothing Then
'use prd...
End If
'IsNot is cleaner
If prd IsNot Nothing Then

19. Using Statement Acquire, Execute, Release
Fast way correctly release resources
Easier to read than Try, Catch, Finally
‘Using block disposes of resource
Using fStr As New FileStream(path, FileMode.Append)
For i As Integer = 0 To fStr.Length
fStr.ReadByte()
Next
‘End of block closes stream
End Using

20. Continue Statement Skips to next iteration of loop
Works with Do, For, While loops
Loop logic is concise, easier to read
For j As Integer = 0 to 5000
While matrix(j) IsNot thisValue
If matrix(j) Is thatValue
‘ Continue to next j
Continue For
End If
Graph(j)
End While
Next j

21. TryCast Returns Nothing if cast fails
Using CType or DirectCast requires Try – Catch logic in case conversion fails.
Using TryCast results in cleaner code.
'runtime exception if obj <> Product type
p = CType(obj, Product)
p = DirectCast(obj, Product)
'TryCast returns Nothing if obj <> Product
p = TryCast(obj, Product)
If p IsNot Nothing Then
'use p...
End If

22. Global Keyword Access to Root (empty) namespace
Complete name disambiguation
Better choice for code generation
'fails if current Namespace contains type named System
Dim sb1 As New System.Text.StringBuilder
'disambiguate framework namespaces
Dim sb2 As New Global.System.Text.StringBuilder

23. Operator Overloading One Mark of a True OO Language
Create your own Types
Conversion Operators
Unsigned Types

24. Operator Overloading Create your own base types
Public Class Complex
Public Real As Double
Public Imag As Double
Public Sub New(ByVal rp As Double, ByVal ip As Double)
Real = rp
Imag = ip
End Sub
Shared Operator +(ByVal lhs As Complex, ByVal rhs As Complex)_
As Complex
Return New Complex(lhs.Real + rhs.Real, lhs.Imag + rhs.Imag)
End Operator
End Class
'new Complex + operator works intuitively
Dim lhs As Complex = New Complex(2.1, 3.3)
Dim rhs As Complex = New Complex(2.5, 4.6)
Dim res As Complex = lhs + rhs
'res.real = 4.6, res.imag = 7.9

25. Conversion Operators You Control Type Conversions
Shared Narrowing Operator CType(ByVal Value As Complex)_
As String
Return Value.Real.ToString & "i" & Value.Imag.ToString
End Operator
Overrides Function ToString(ByVal Value As Complex) _
End Function

26. Unsigned Types Full support in the language
Full platform parity
Easier Win32 API calls and translation
Memory and performance win
Dim sb As SByte = ‘Error:negative
Dim us As UShort
Dim ui As UInteger
Dim ul As ULong
‘Full support in VisualBasic modules
If IsNumeric(uInt) Then
‘ Will now return true
End If

27. Other Features Rounding out Framework Support
Property Accessor Accessibility
Custom Event Accessors
Partial Types
Application Level Events
Compiler Warnings
Explicit Array Bounds

28. Accessor Accessibility Granular accessibility on Get and Set
Forces calls to always use get, set
Easy way to enforce validation
Property Salary() As Integer
Get
Return mSalary
End Get
Private Set( value As Integer)
If value < 0 Then
Throw New Exception(“Not Available”)
End If
End Set
End Property

29. Custom Event Accessors Define and Control Custom Events
Code gen when you type Custom keyword
Public Custom Event NameChanged As EventHandler
AddHandler(ByVal value As EventHandler)
'hook handler to backing store
End AddHandler
RemoveHandler(ByVal value As EventHandler)
'remove handler from backing store
End RemoveHandler
RaiseEvent(ByVal sender As Object, _
ByVal e As System.EventArgs)
'invoke listeners
End RaiseEvent
End Event

30. Partial Types Single structure, class in multiple files
Separates designer gen into another file
Team dev / factor implementation
Public Class Form1
Inherits Windows.Forms.Form
‘ Your Code
End Class
Partial Class Form1
‘ Designer code
Sub InitializeComponent()
‘ Form controls
End Sub

31. Application Level Events Similar to ASP.NET Global.asax
Events exposed:
Startup
Shutdown
StartupNextInstance
NetworkAvailabilityChanged
UnhandledException
Found in ApplicationEvents.vb file

32. Visual Basic Warnings Early warning of runtime behavior
Overlapping catch blocks or cases
Recursive property access
Unused Imports statement
Unused local variable
Function, operator without return
Reference on possible null reference
Option Strict broken down
“Late binding”
Visual Basic Style Conversions
Etc.

33. Explicit Array Bounds Lower Bound Must Still be 0
More precise array declarations
Dim a(10) As Integer 'old way
Dim b(0 To 10) As Integer 'new way

34. Summary The Best Visual Basic Ever
VB Language complete, full OO support
Feature parity between all .NET languages
IDE support for language productivity
GoLive licenses available for Beta 2 now from Microsoft

35. Resources
Session: VS 2005 Development Environment Keith Kabza – 1:50 to 2:50 in this room
Visual Basic development center:
Product feedback center:
Stan Schultes

36. Acknowlegements
Some slides and content borrowed from Amanda Silver and Steven Lees of the VB Team at Microsoft.