Francesco Balena – Code Architects, Italy

VB6 Migration:Tips, Traps, and Techniques

Me.About the Programming Microsoft Visual Basic series

MSDN Regional director, Italy

VB Migration Partner

www.vbmigration.com

Code Architects Visual Studio Industry Partner (VSIP)

the only Microsoft ISVNXT partner specialized in conversion and modernization of VB6 apps

customers in Europe, United States & Canada, Australia and Asia

dozens of millions of lines of code migrated

official Microsoft Case study published on Microsoft.com, ERP system of about 1M lines of code

migration FAQswhy migrating to .NETmigrating vs. porting vs. extendingusing conversion toolsthe C# alternative

“language impedance” data types type-char suffix Array lower bounds Optional params As New variables Byval argument passing Defxxx array rank missing As As Any parameters block variables date as double array assignments callbacks in Declare As New arrays UDT initialization Variants default parameterless members Gosub On Goto/GoSub Byref ParamArray Fixed-length strings UDT assignments byte-oriented string functions enum/number conversions IsMissing Empty value Null propagation VarPtr, ObjPtr, StrPtr class termination IDisposable objects default members in late-binding OLE control Line and Shape controls control arrays graphic methods ScaleMode property DrawMode property DAO and RDO data-binding ADO data-binding ADO data-bound classes DataEnvironment VBControlExtender object PropertyPages UserDocuments “classic” drag-and-drop OLE drag-and-drop Extender and Ambient properties DDE WebClasses DHTML Pages Sub Main in DLLs SingleUse classes Global classes COM+ components class persistence Print and Printers App, Screen, Forms objects ActiveX EXEs popup menus

“language impedance” (UW)

“language impedance” (VBMP)

hidden traps

• strings• parameter passing• math operations• collections• fields• ... and a lot more

conceptsparser and code analyzerpre/post processingmigration pragmascode generation enginesupport librarycode analysis & refactoring

concepts (in 75 minutes)parser and code analyzerpre/post processingmigration pragmascode generation enginesupport librarycode analysis & refactoring

before migrating... use array with Lbound = 0 avoid Variants, if possible

late binding Null propagation

create wrapper methodsfile I/Ographicsdata accessWindows API calls (As Any, VarPtr, StrPtr)

remove unused and unreachable code

support library many VB6 methods are missing or don’t

preserve functional equivalence CDate, IsDate, IsObject Str, StrConv AscB, ChrB, LeftB, MidB, RightB, ... MsgBox, InputBox FileDateTime, Dir VarType, TypeName IsMissing, IsEmpty, IsNull DoEvents SavePicture, LoadPicture ...

post-processing

• process the output from UW– leverage existing upgrade warnings

• can‘t replace a real parser, but it’s enough for many common issues

post-processing

examples library methodsDoEventsControls.AddUDT initializationfixed-length strings inside UDTdefault methods in late-binding mode

migration pragmas

similar to compiler directives

• special remarks with '## prefix '## ArrayBounds ForceZero

project, file, method, variable scope '## project:ConvertGosubs True '## myvar.InferType

convert-test-fix methodology

migration pragmas examples

ExcludeStatement InsertStatement ReplaceStatement AutoNew AutoDispose ReplaceCurrentFile IncludeFile

refactoring with PostProcess Not x Is y x IsNot y Dim x As Short : x = 1 Dim x As Short = 1 Dim x As Short: For x = 1 For x As Short =

1 While…End While Do…Loop If x = True Then If x Then If x = False Then If Not x Then If bool1 And bool2 If bool1 AndAlso bool2 … If bool1 Or bool2 If bool1 OrElse bool2 …

more details here: www.vbmigration.com/blog

VB Migration Partner VB6 project groups all VB6 keywords (except VarPtr, ObjPtr, StrPtr)

advanced code analysis and refactoring 70+ VB6 controls, drag-and-drop, popup

menus graphic methods, user-defined ScaleMode null propagation in expressions (the VB6Variant

type) ADO, DAO, RDO data-binding try-catch, gosubs, nested Ifs, type inference ADODB -> ADO.NET migration (ADOLibrary)

pragmas & convert-test-fix methodology

VB6 migration: tips, traps, and tricks knowledge base, videos, code samples,

articles, links, and resources atwww.vbmigration.com

slides available atwww.slideshare.net/VBMigrationPartner

blogwww.vbmigration.com/blog

LinkedIn Group on VB6 Migrationwww.linkedin.com/groups?gid=3074090

Facebook Fan Page on VB6 Migrationfacebook.com/FrancescoBalenaOnVB6Migration

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