Friday, May 30, 2008

Microsoft Visual Basic .NET

Visual Basic .NET (VB.NET) is an object-oriented computer language that can be viewed as an evolution of Microsoft's Visual Basic (VB) implemented on the Microsoft .NET framework. Its introduction has been controversial, as significant changes were made that broke backward compatibility with older versions and caused a rift within the developer community.
Visual Basic .NET (VB 7)
The original Visual Basic .NET was released alongside Visual C# and ASP.NET in 2002. C# — widely touted as Microsoft's answer to Java — received the lion's share of media attention, while VB.NET (sometimes known as VB7) was not widely covered. As a result, few outside the Visual Basic community paid much attention to it.[citation needed]
Those who did try the first version found a powerful but very different language under the hood, with disadvantages in some areas, including a runtime that was ten times as large to package as the VB6 runtime and an increased memory footprint.[citation needed]
Visual Basic .NET 2003 (VB 7.1)
Visual Basic .NET 2003 was released with version 1.1 of the .NET Framework. New features included support for the .NET Compact Framework and a better VB upgrade wizard. Improvements were also made to the performance and reliability of the .NET IDE (particularly the background compiler) and runtime.
In addition, Visual Basic .NET 2003 was also available in the Visual Studio .NET 2003 Academic Edition (VS03AE). VS03AE is distributed to a certain number of scholars from each country for free.
Visual Basic 2005 (VB 8.0)
Visual Basic 2005 is the name used to refer to the update to Visual Basic .NET, Microsoft having decided to drop the .NET portion of the title.
For this release, Microsoft added many features, including:
* Edit and Continue - probably the biggest "missing feature" from Visual Basic .NET, allowing the modification of code and immediate resumption of execution
* Design-time expression evaluation
* The My pseudo-namespace (overview, details), which provides:
o easy access to certain areas of the .NET Framework that otherwise require significant code to access
o dynamically-generated classes (notably My.Forms)
* Improvements to the VB-to-VB.NET converter [2]
* The Using keyword, simplifying the use of objects that require the Dispose pattern to free resources
* Just My Code, which hides boilerplate code written by the Visual Studio .NET IDE
* Data Source binding, easing database client/server development
The above functions (particularly My) are intended to reinforce Visual Basic .NET's focus as a rapid application development platform and further differentiate it from C#.
Visual Basic 2005 introduced features meant to fill in the gaps between itself and other "more powerful" .NET languages, adding:
* .NET 2.0 languages features such as:
o generics [3]
o Partial classes, a method of defining some parts of a class in one file and then adding more definitions later; particularly useful for integrating user code with auto-generated code
o Nullable Types
* XML comments that can be processed by tools like NDoc to produce "automatic" documentation
* Operator overloading
* Support for unsigned integer data types commonly used in other languages
IsNot Patent
One other feature of Visual Basic 2005 is the conversion of If Not X Is Y to If X IsNot Y which gained notoriety when it was found to be the subject of a Microsoft patent application.
Visual Basic 2005 Express
As part of the Visual Studio product range, Microsoft created a set of free development environments for hobbyists and novices, the Visual Studio 2005 Express series. One edition in the series is Visual Basic 2005 Express Edition, which was succeeded by Visual Basic 2008 Express Edition in the 2008 edition of Visual Studio Express.[8]
The Express Editions are targeted specifically for people learning a language. They have a streamlined version of the user interface, and lack more advanced features of the standard versions. On the other hand, Visual Basic 2005 Express Edition does contain the Visual Basic 6.0 converter, so it is a way to evaluate feasibility of conversion from older versions of Visual Basic.

Visual Basic 2008 (VB 9.0)
Visual Basic 9.0 was released together with the Microsoft .NET Framework 3.5 on November 19, 2007.
For this release, Microsoft added many features, including:
* A true ternary operator If (boolean, value, value) to replace the IIF function.
* Anonymous types
* Support for LINQ
* Lambda expressions
* XML Literals
* Type Inference
Visual Basic 'VBx' (VB 10.0)
Visual Basic 10, also known as VBx, will offer support for the Dynamic Language Runtime. VB 10 is planned to be part of Silverlight 2.0.[citation needed]
Relation to older versions of Visual Basic (VB6 and previous)
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 that 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. Two important data type changes occurred with the move to VB.NET. Compared to VB6, the Integer data type has been doubled in length from 16 bits to 32 bits, and the Long data type has been doubled in length from 32 bits to 64 bits. This is true for all versions of VB.NET. A 16-bit integer in all versions of VB.NET is now known as a Short. 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 an object-based programming language 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. Documentation is available to cover changes in the syntax, debugging applications, deployment and terminology.

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