DEV230
Upgrading VB 6 Applications to
Visual Basic .NET
Keith Pleas
Architect, Guided Design
keithp@guideddesign.com
Overview
Language changes – code, object, data
Classic Visual Basic “Ruby” forms to
Windows Forms
Upgrade Tools & Utilities
The Upgrade Process - Examples
Structured Exception
Handling
Try…Catch…Finally
Throw an error – similar to Err.Raise
"On Error Goto…" still supported
Err object still available (Compatibility)
Depends on “exception classes” than hold
information about exception
Block scoping of variables
Structured Exception Handling
Example
Try
' Some typical processing logic
rsRecordset.Update
Catch excError as Exception When Expression
' This code runs when an error occurs
' in the code above
LogError ("Unable to update the recordset")
Finally
' This code always runs, either after the
' Try code if there was no error, or after
' the Catch code if there was
rsRecordset.MoveNext
End Try
Changes in Data Types
Integer
 Short (System.Int16)
Long
 Integer (System.Int32)
Long
 64-bit value (System.Int64)
Currency  Decimal (System.Decimal)
Variant
 Object (System.Object)
New Char holds a single character
Often used for character arrays
Actually 2 bytes to hold Unicode
Fixed-length string not a base .NET type
Declaration Syntax Changes
Multiple declarations on a single line
assumed to be the same type
Dim x, y As Integer
' both are integers
Initial value now supported
Dim intHours As Integer = 20
Dim intMinutes as Integer = intHours * 60
Array Declaration Changes
Must use Dim for initial declaration of
arrays – Redim for size change only.
Initial values for arrays supported
Dim strNames() as String = ("Moe", "Larry", "Curly")
Option base always zero
Array size works the same as in VB6, so
declaring x(5) gives 6 elements (0…5)
Retired Keywords
These keywords are retired and no longer
supported
GOSUB (Return has different usage)
DefType statements (such as DefInt, DefStr,
etc.)
On x GoTo … (computed GoTo’s)
Let
Option Base 0 | 1
VarPtr, ObjPtr, StrPtr
Structures Replace UDTs
UDT in VB6 could look like this:
Type TransferRecord
RecID As Integer
Location As String*20
Status As Boolean
End Type
Closest match in VB.NET is:
Structure TransferRecord
Public RecID As Integer
Public Location As String 'Variable length string!
Public Status As Boolean
End Structure
No fixed-length strings (caveat)
<VBFixedString(15)> Public Title As String 'Fixed!
More Replaced Keywords
VarType
GetType in System.Object
Date & Time
System.DateTime
Graphics methods (Line, Circle, …)
System.Graphics.DrawLine
RSet, LSet
PadRight, PadLeft in System.String
Rnd, Randomize
System.Random
Miscellaneous Changes
Option Strict to control implicit casting
No implicit loading of forms (a form is just
another class)
Required parentheses on methods,
functions, and subroutines
Parameters are ByVal by Default
Block scoping of variables
Class Changes - Properties
Syntax different from VB 6.0
Dim myData as Integer = 10
Public Property Data( ) As Integer
Get
Return MyData
End Get
Set(ByVal Value As Integer)
myData = Value
End Set
End Property
ReadOnly, WriteOnly
Default (must have parameters)
Class Changes - Methods
Same general syntax as VB 6.0
Arguments are now ByVal by default
Public Sub DoStuff(x As Integer)
…
End Sub
Public Function GetStuff( ) As Integer
…
End Function
Class Changes - Events
VB 6.0 Event, RaiseEvent, and
WithEvents still supported:
Class TimerState
Public Event UpdateTime(dblJump As Double)
Public Sub TimerTask(Duration As Double)
RaiseEvent UpdateTime(Timer - dblJump)
End Sub
End Class
Public WithEvents mText As TimerState
Call mText.TimerTask(9.84)
Class Changes - Handling
Events
Declared using "Handles object.event "
Private Sub Button1_Click(ByVal sender as Object, _
ByVal e as EventArgs) Handles Button1.Click
…
End Sub
Dynamic "AddHandler", "RemoveHandler"
Private Sub myClick(ByVal sender As Object, _
ByVal e As EventArgs)
…
End Sub
AddHandler Button1.Click, New EventHandler(AddressOf myClick)
RemoveHandler Button1.Click, AddressOf myClick
Events are Really Delegates
“Objects That Call Methods of Other
Objects”
Similar to function pointers in other
languages (like C++)
Reference type inherited from
System.Delegate
Type-safe, Secure, Managed Objects
Can be linked (combined) together:
d = CType([Delegate].Combine(d, y.cb), OutputDelegate)
Constructors
Sub New replaces Class_Initialize
New runs when object is instantiated
Public Sub New( )
…
End Sub
Can be Overloaded (no keyword)
Public Sub New(ByVal i As Integer)
…
End Sub
Public Sub New(ByVal i As Integer, ByVal s As String)
…
End Sub
Instantiating Objects
Instantiate and initialize objects at the
same time or separately
' Separate (as in VB 6.0)
Dim my1 As myClass
my1 = New myClass( ) 'Default constructor
' At the same time
Dim my2 As myClass = New myClass( )
Dim my3 As New myClass( )
' Other constructors
Dim my4 As New myClass(10)
Dim my5 As myClass = New myClass(10)
Destructors
Used to clean up resources
Executed when destroyed by Garbage
Collection (GC)
Important: destruction may not happen
immediately
Replaces Class_Terminate event
Dispose and Finalize Methods
…\FrameworkSDK\Samples\Technologies\
GarbageCollection\VB
Upgrading Data
Easy: ADO to ADO via Interop
Medium: DAO / RDO to ADO (Interop)
DAO / RDO Databinding not supported
Redesign: DAO/RDO/ADI to ADO.NET
ADODB
DAO
RDO
ADODB.dll
Interop.DAO.dll
Interop.RDO.dll
Strong, in GAC & PIA
Not Strong
Not Strong
VB 6.0 “Ruby” Forms to
Windows Forms
Windows Forms Differences
A rich new object library
Coordinate system
Arrange & Dock
New features - Visual Inheritance
API calls to GDI+ Managed Classes
“Hello World” Form Class
Imports System
Imports System.Windows.Forms
Public Class Form1
Inherits Form
Public Sub New()
MyBase.New()
InitializeComponent()
End Sub
Private Sub InitializeComponent()
Me.Name = "Form1"
Me.Text = "Hello World"
End Sub
End Class
Form Code Changes
Form layout
Me.Move (Screen.Width - Me.Width), _
(Screen.Height - Me.Height) / 2
Me.StartPosition = FormStartPosition.CenterScreen
Object changes
Me.MousePointer = vbHourglass
Me.Cursor.Current = Cursors.WaitCursor
Dynamic Layout
TextBox1.Anchor = _
AnchorStyles.Top _
Or AnchorStyles.Left) _
Or AnchorStyles.Right)
Panel1.Dock = DockStyle.Bottom
Changes to modal dialogs
VB6 code
Dim frmDialogForm As DialogForm
Set frmDialogForm = New DialogForm
frmDialogForm.Show vbModal
VB.NET code
Dim frmDialogForm As New DialogForm
frmDialogForm.ShowDialog
Built-in DialogResult property to
discover user action
Owned forms
Always displayed above “owner form”
Do not interfere with owner form operation
Used for tutorial windows, search and
replace box
Can be set by owner form –
AddOwnedForm method
Can be set by owned form – Owner
property
Also TopMost property
Upgrading APIs (1 of 2)
Generally works with simple APIs
These Need Modification:
AsAny
User Defined Types
AddressOf
Examples:
GetWindowsDirectory
GetOpenFileName
SendMessage
Upgrading APIs (2 of 2)
Consider replacing with GDI+
Not Supported
ScaleMode (only pixels supported)
AutoRedraw (use Paint event)
HasDC, HDC
DrawMode, DrawStyle, DrawWidth (use Pen
object)
Requires Re-architecting
ActiveX Documents
DHTML pages
Add-In extensibility
Property pages
OLE control
Leave in VB 6.0 or
switch to ActiveX EXE
then upgrade
Navigate to VB.NET
Use new object model
Property browser
WebBrowser control
Tools & Utilities for
Upgrading
“Code Advisor” a.k.a “FixIt”
Configuration
HTML summary
Extending the
“Code Advisor”
Dim prpObj As Property
'FIXIT: Declare 'vTmp' with an early-bound data type
Dim vTmp As Variant
'FIXIT: Declare 'vNew' with an early-bound data type
Dim vNew As Variant
Dim frmProp As New frmProperty
FixIT90210ae-R1672-R1B8ZE
FixIT90210ae-R1672-R1B8ZE
Upgrade Wizard
EXE & DLL
Copies project
Creates reports
Links to Help
Four Levels
Issue
ToDo
Warning
Note
No Automatic Upgrade
Requires Finishing
Possible Behavior Change
Informational
Before Upgrade Wizard
Must be able to compile VB6 app
Must have design time license files
Must have all referenced components
(required for Interop assemblies)
Should remove unused references,
particularly for ActiveX controls
’Upgrade Visual Basic 6 Code’
'UPGRADE_WARNING: Couldn't resolve default property of object Me.Left. Click for more
'UPGRADE_WARNING: Couldn't resolve default property of object Me.Width. Click for mor
Me.Left = (VB6.PixelsToTwipsX(System.Windows.Forms.Screen.PrimaryScreen.Bounds.Widt
'UPGRADE_WARNING: Couldn't resolve default property of object Me.Top. Click for more:
'UPGRADE_WARNING: Couldn't resolve default property of object Me.Height. Click for mo
Me.Top = (VB6.PixelsToTwipsY(System.Windows.Forms.Screen.PrimaryScreen.Bounds.Heigh
Upgrading Projects To
Visual Basic .NET
Upgrade #1- Form Controls
 System.Windows.Forms.Label
 System.Windows.Forms.PictureBox
 System.Windows.Forms.Timer
 System.Windows.Forms.Label




Data
Image
Timer
Line


DirListBox  Compatibility.VB6.DirListBox
FileListBox  Compatibility.VB6.FileListBox
Upgrading ActiveX Controls

Microsoft Windows Common Controls 6.0
 MSCOMCTL.OCX


Interop.ComctlLib.dll
AxInterop.MSComctlLib.dll
VisualBasic.dll








Collection
Constants (vbCancel, vbCrLf…
ControlChars (CrLf, Tab,…
DateAndTime (DateAdd…
ErrObject
FileSystem
Information (IsDate, IsDBNull, …
VBMath
VisualBasic.Compatibility.dll
Caution: Functions in the
Visual Basic 6.0 Compatibility
library are provided only for
use by the upgrading tools.
Although it is possible to use
this library when writing new
code, there is no guarantee
that it will be supported in
future versions of Visual
Basic.
Class DirListBoxEx
Inherits Microsoft.VisualBasic.Compatibility.VB6.DirListBox
End Class
Dealing with Transactions
VB 6.0
Stored
Procedures
MTS / COM+
Transactions
.NET
Stored
Procedures
EnterpriseServices
(COM+)
.NET Framework
Transactions
(Manual)
Dealing with Transactions
MTS or COM+ objects were not upgraded
The project that you are attempting to upgrade has a
reference to the COM+ Services Type Library
(Comsvcs.dll) that cannot be upgraded. In Visual
Basic 6.0, this library was used to access Microsoft
Transaction Services (MTS). In Visual Basic .NET,
MTS is replaced by transaction processing
functionality in the .NET Framework.
Because of differences in the transaction processing
models, existing code will need to be deleted and
replaced by code that uses .NET transaction
processing.
Upgrade #2 – VisData…
MDI Application, test for data access
35 Forms – 8,343 lines
1 VB Module – 2,325 lines
1 Class Module – 103 lines
3 ActiveX Controls
Common Dialog Control
Data Bound Grid Control
Common Controls
485KB source (no .FRX or resources)
Upgrade #2: …Results
22 Minutes, 519 Tasks
103 Errors
App, Printer, Tag, Data Control
16 ToDos
Behavior must be checked
400 Upgrade Warnings
MousePointer, Resize, SelectedIndexChanged
Default properties
Upgrade #3: Duwamish
bas cls
DSO 0
3
Bus Logic
Data Access
Workflow
KB
41
IO
1
Lines
1319
Err Warn Min
3  120 1
2
0
1
7
1
1
327
6
35
1
0
2
11036
189
1078
1
1
0
3
12
409
4
13622
5
 Dim / ReDim Preserve
 MTS objects not upgraded
29
0
17
5
1
2
166
9
Upgrade #4: Medisys
2 Tier Client Server
SQL Server 7.0 access via RDO
MDI Application
Extensive use of ActiveX controls
129 Forms
12 VB code modules
76 Class modules
134,000 lines of code
Code 95% upgraded (6,700 lines to fix)
Summary
Use Wizard for language & object changes
Upgrading adds value
Stronger type checking
Inheritance
Easier integration with other languages
Better development experience
No limits
Merely upgrading versus using the “.NET
Force”
Ask The Experts
Get Your Questions Answered
13:00 to 15:00 Thursday 3 July
Community Resources
Community Resources
http://www.microsoft.com/communities/default.mspx
Most Valuable Professional (MVP)
http://www.mvp.support.microsoft.com/
Newsgroups
Converse online with Microsoft Newsgroups, including Worldwide
http://www.microsoft.com/communities/newsgroups/default.mspx
User Groups
Meet and learn with your peers
http://www.microsoft.com/communities/usergroups/default.mspx
Suggested Reading & Resources
The tools you need to put technology to work!
TITLE
Upgrading Microsoft® Visual
Basic® 6.0 to Microsoft Visual
Basic .NET: 0-7356-1587-X
Available
Today
Microsoft Press books are 20% off at the TechEd Bookstore
Also buy any TWO Microsoft Press books and get a FREE T-Shirt
evaluations
© 2003 Microsoft Corporation. All rights reserved.
This presentation is for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS OR IMPLIED, IN THIS SUMMARY.