Appendix A. Visual Basic .NET

Paul Vick

Appendix A credit: Paul Vick, Microsoft Corporation. Copyright 2002 Microsoft Corporation. All rights reserved.

The BASIC language has been a member of Microsoft's language products from the very beginning ”indeed, the first product produced by Microsoft was a BASIC interpreter for the Altair written by Bill Gates and Paul Allen. Every major platform produced by Microsoft has had a companion BASIC product, from BASIC-A and GW-BASIC for DOS through Visual Basic for the Windows platforms. As such, it is no surprise that one of the first languages to be ported to the .NET platform would be BASIC.

The move from Windows to .NET, though, was in many ways a much bigger and more difficult step for BASIC than the move from DOS to Windows. The sheer magnitude and complexity of the .NET platform meant that a number of new concepts had to be integrated into the language. Previous versions of Visual Basic were intimately tied to the specifics of the Win32 APIs and its Common Object Model (COM). Although .NET is built on top of Win32 and COM, .NET nonetheless revises or replaces many of the concepts of the underlying platform. And finally, because the .NET platform was designed as an inherently multilingual platform, more consideration had to be given to interoperating with other languages than had been given in the past.

This appendix discusses a number of the major issues that the Visual Basic .NET team dealt with when designing the latest revision of the language. A full discussion of all the changes between Visual Basic 6.0 and Visual Basic .NET is well beyond the space allowed here ”it could easily fill a book in its own right. However, the issues discussed are intended to give an idea of the kinds of problems and solutions that a language author might encounter when adapting an established language to the .NET platform. There is also some discussion at the end of the chapter of language changes made that were not directly related to the move to the .NET platform. These will mostly be of interest to Visual Basic developers who are familiar with previous versions of the language.