Visual Basic for Applications
|This article relies too much on references to primary sources. (March 2013)|
|Stable release||7.1 (Office 2013)|
|Typing discipline||Static/Dynamic Hybrid, Strong/Weak Hybrid|
|OS||Microsoft Windows, Mac OS X|
|License||Commercial proprietary software|
|QuickBASIC, Visual Basic|
Visual Basic for Applications enables building user-defined functions (UDFs), automating processes and accessing Windows API and other low-level functionality through dynamic-link libraries (DLLs). It supersedes and expands on the abilities of earlier application-specific macro programming languages such as Word's WordBasic. It can be used to control many aspects of the host application, including manipulating user interface features, such as menus and toolbars, and working with custom user forms or dialog boxes.
As its name suggests, VBA is closely related to Visual Basic and uses the Visual Basic Runtime Library, but it can normally only run code within a host application rather than as a standalone program. It can, however, be used to control one application from another via OLE Automation. For example, it can be used to automatically create a Word report from Excel data, which are automatically collected by Excel from polled observation sensors. VBA has the ability to use (but not create) (ActiveX/COM) DLLs, and later versions add support for class modules.
VBA is built into most Microsoft Office applications, including Office for Mac OS X (apart from version 2008) and other Microsoft applications such as Microsoft MapPoint and Microsoft Visio, as well as being at least partially implemented in other applications such as ArcGIS, AutoCAD, CATIA, Corel Draw and WordPerfect.
Code written in VBA is compiled to a proprietary intermediate language called P-code (packed code), which the hosting applications (Access, Excel, Word, Outlook, and PowerPoint) store as a separate stream in COM Structured Storage files (e.g.,
.xlsx) independent of the document streams. The intermediate code is then executed by a virtual machine (hosted by the hosting application). Despite its resemblance to many old BASIC dialects (particularly Microsoft BASIC, from which it is indirectly derived), VBA is incompatible with any of them except Visual Basic, where source-code of VBA modules and classes can be directly imported, and which shares the same library and virtual machine. Compatibility ends with Visual Basic version 6; VBA is incompatible with Visual Basic .NET (VB.NET). VBA is proprietary to Microsoft and, apart from the COM interface, is not an open standard.
Interaction with the host application uses OLE Automation. Typically, the host application provides a type library and application programming interface (API) documentation which document how VBA programs can interact with the application. This documentation can be examined from inside the VBA development environment using its Object Browser.
Visual Basic for Applications programs which are written to use the OLE Automation interface of one application cannot be used to automate a different application, even if that application hosts the Visual Basic runtime, because the OLE Automation interfaces will be different. For example, a VBA program written to automate Microsoft Word cannot be used with a different word processor, even if that word processor hosts VBA.
Conversely, multiple applications can be automated from the one host by creating Application objects within the VBA code. References to the different libraries must be created within the VBA client before any of the methods, objects, etc. become available to use in the application. This is achieved through what is referred to as Early or Late Binding. These application objects create the OLE link to the application when they are first created. Commands to the different applications must be done explicitly through these application objects in order to work correctly.
VBA code written in Microsoft Access can establish references to the Excel, Word and Outlook libraries; this will allow creating an application that runs a query in Access, exports the results to Excel, formats the text, then writes a mail merge document in Word that it automatically e-mails to each member of the original query through Outlook.
VBA programs can be attached to a menu button, a macro, a keyboard shortcut, or an OLE/COM event, such as the opening of a document in the application. The language provides a user interface in the form of UserForms, which can host ActiveX controls for added functionality.
Like any common programming language, VBA macros can be created with malicious intent. Using VBA, most of the security features lie in the hands of the user, not the author. The VBA host application options are accessible to the user. The user who runs any document containing VBA macros can preset the software with user preferences. End-users can protect themselves from attack by disabling macros from running in an application or by granting permission for a document to run VBA code only if they are sure the source of the document can be trusted.
As of July 1, 2007, Microsoft no longer offers VBA distribution licenses to new customers. Microsoft intended to add .NET-based languages to the current version of VBA ever since the release of the .NET Framework, of which versions 1.0 and 1.1 included a scripting runtime technology named Script for the .NET Framework. Visual Studio .NET 2002 and 2003 SDK contained a separate scripting IDE called Visual Studio for Applications (VSA) that supported VB.NET. One of its significant features was that the interfaces to the technology were available via Active Scripting (VBScript and JScript), allowing even .NET-unaware applications to be scripted via .NET languages. However, VSA was deprecated in version 2.0 of the .NET Framework, leaving no clear upgrade path for applications desiring Active Scripting support (although "scripts" can be created in C#, VBScript, and other .NET languages, which can be compiled and executed at run-time via libraries installed as part of the standard .NET runtime).
Support for VBA in the Mac OS X version of Microsoft Office was dropped (for one version) with the release of Microsoft Office 2008 for Mac. The official reason given[who?] was that VBA relied heavily on machine code written for the PowerPC architecture, and that rewriting this code for dual PowerPC/Intel architectures would have added another two years to the development of the suite. However, the Office suite can be automated via AppleScript to an extent. VBA was restored in Microsoft Office for Mac 2011. Microsoft has clearly stated that they have no plans to remove VBA from the Windows version of Office.
With Office 2010, Microsoft has introduced VBA7 which now contains a true pointer data type: LongPtr. This new data type allows referencing 64-bit address space. The 64-bit install of Office 2010 does not support common controls of MSComCtl (TabStrip, Toolbar, StatusBar, ProgressBar, TreeView, ListViews, ImageList, Slider, ImageComboBox) or MSComCt2 (Animation, UpDown, MonthView, DateTimePicker, FlatScrollBar) so legacy 32-bit code ported to 64-bit VBA code that depends on these common controls will not function. The 32-bit version of Office 2010 is unaffected by this issue. VBA7 includes no 64-bit version of the common controls, so it leaves developers with no means to migrate VBA applications to 64-bits. Microsoft suggests contacting the software vendor for 64-bit versions of VBA controls.
Visual Studio Tools for Applications
|Wikiversity has learning materials about Visual Basic for Applications|
- ACC: Visual/Access Basic Is Both a Compiler and an Interpreter
- Visual Studio for Applications
- Introducing Visual Studio for Applications
- Script happens .NET: MSDN
- Microsoft Takes Wraps Off VSA Development Technology
- VSA scripting in .NET
- "WWDC: Microsoft updates Universal status of Mac apps". Macworld. 2006-08-07. Retrieved 2007-05-25.
- Office 2008 without VBA
- The Reports of VBA's Demise Have Been Greatly Exaggerated
- Clarification on VBA Support
- "Compatibility Between the 32-bit and 64-bit Versions of Office 2010"
|Wikibooks has a book on the topic of: Visual Basic|