Web Design:VB vs VB.NET

Whether Visual Basic .NET should be considered as just another version of Visual Basic or a completely different language is a topic of debate. This is not obvious, as once the methods that have been moved around and which can be automatically converted are accounted for, the basic syntax of the language has not seen many "breaking" changes, just additions to support new features like structured exception handling and short circuited expressions. One simple change that can be confusing to previous users is that of Integer and Long data types, which have each doubled in length; a 16-bit integer is known as a Short in VB.NET, while Integer and Long are 32 and 64 bits respectively. Similarly, the Windows Forms GUI editor is very similar in style and function to the Visual Basic form editor.

The things that have changed significantly are the semantics — from those of a procedural programming environment running on a deterministic, reference-counted engine based on COM to a fully object-oriented language backed by the .NET Framework, which consists of a combination of the Common Language Runtime (a virtual machine using generational garbage collection and a just-in-time compilation engine) and a far larger class library. The increased breadth of the latter is also a problem that VB developers have to deal with when coming to the language, although this is somewhat addressed by the My feature in Visual Studio 2005.

The changes have altered many underlying assumptions about the "right" thing to do with respect to performance and maintainability. Some functions and libraries no longer exist; others are available, but not as efficient as the "native" .NET alternatives. Even if they compile, most converted VB6 applications will require some level of refactoring to take full advantage of the new language. Extensive documentation is available to cover changes in the syntax, debugging applications, deployment and terminology. Comparative samples

The following simple example demonstrates similarity in syntax between VB and VB.NET. Both examples pops a message box saying "Hello, World" with an OK button.

Classic VB example:

 Private Sub Command1_Click()

  

    MsgBox "Hello, World"

  

 End Sub

A VB.NET example:

 Private Sub button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles button1.Click

  

    MsgBox("Hello, World")

  

 End Sub

Note that all procedure calls must be made with parentheses in VB.NET, whereas these were only required for function calls (however in VB6 they could be used in procedure calls as well by using the Call keyword)

Also note that the names "command1" and "button1" are not obligatory. However, these are default names for a command button in VB6 and VB.NET respectively.

The following example demonstrates the difference between VB6 and VB.NET. Both examples unload the active window.

Classic VB Example:

 Private Sub cmdClose_Click()

  

       Unload Form1

  

 End Sub

A VB.NET example:

 Private Sub cmdClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdClose.Click

  

       Form1.Close()

  

 End Sub

Note that in both samples the names "cmdClose" and "Form1" are user-defined. Controversy concerning VB.NET

Many long-time Visual Basic programmers have complained about Visual Basic .NET, because initial versions dropped a large number of language constructs and user interface features that were available in VB6 (which is now no longer sold), and changed the semantics of those that remained; for example, in VB.NET parameters are (by default) passed by value, not by reference. Detractors refer to VB.NET as Visual Fred (what they think it should have been called, to distinguish it from VB6) or DOTNOT. On March 8, 2005, a petition was set up in response to Microsoft's refusal to extend its mainstream support for VB6 at the end of that month.

VB.NET's supporters state that the new language is in most respects more powerful than the original, incorporating modern object oriented programming paradigms in a more natural, coherent and complete manner than was possible with earlier versions. Opponents tend not to disagree with this, instead taking the position that although VB6 has flaws in its object model, the cost in terms of redevelopment effort is too high for any benefits that might be gained by converting to VB.NET. Independent developers producing software for Internet distribution have also taken issue with the size of the runtime.

Microsoft supplies an automated VB6-to-VB.NET converter with Visual Studio .NET, which has improved over time, but it cannot convert all code, and almost all non-trivial programs will need some manual effort to compile. Most will need a significant level of refactoring to work optimally. Visual Basic programs that are mainly algorithmic in nature can be migrated with few difficulties; those that rely heavily on such features as database support, graphics, unmanaged operations or on implementation details are more troublesome. Unfortunately, these functions are core to many business applications.

In addition, the runtime libraries for VB6 programs (excluding custom COM objects) are provided with Windows 98 SE and above, while VB.NET programs require the installation of the significantly larger .NET Framework, only scheduled to be introduced as standard with Windows Vista, Windows XP Media Center Edition, Windows XP Tablet PC Edition and Windows Server 2003. This has created much inconvenience to both programmers and users.

Microsoft's response to developer dissatisfaction has focused around making it easier to move new development and shift existing codebases from VB6 to VB.NET. Their latest offering is the VBRun website, which offers code samples and articles for:

completing common tasks in VB6, like creating a print preview

integrating VB6 and VB.NET solutions (dubbed VB Fusion)

converting VB6 code to VB.NET ..

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