computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...

, a Visual Basic Extension (commonly abbreviated VBX) or custom control, was the component model used in

Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washin ...

Visual Basic Visual Basic is a name for a family of programming languages from Microsoft. It may refer to: * Visual Basic .NET (now simply referred to as "Visual Basic"), the current version of Visual Basic launched in 2002 which runs on .NET * Visual Basic ( ...

versions 1.0 to 3.0. It is still supported in the 16-bit version of version 4.0, but was made obsolete by OCXs. VBX has also been supported in the first, 16-bit version of

Borland Delphi Delphi is a general-purpose programming language and a software product that uses the Delphi dialect of the Object Pascal programming language and provides an integrated development environment (IDE) for rapid application development of desktop, ...

. The VBX specification was created so that developers could extend

. Since at the time Visual Basic was an

interpreted language In computer science, an interpreter is a computer program that directly executes instructions written in a programming or scripting language, without requiring them previously to have been compiled into a machine language program. An interprete ...

with limited speed, VBXs, which were most often written in C or C++, provided the ability to create very powerful and efficient user interface sub-components which could be assembled into applications using Visual Basic as the glue. Visual Basic 4.0 added support for the newer OLE Controls or OCXs (which became ActiveX controls), implicitly deprecating VBX controls. OCXs are based on the Component Object Model. Each version of Visual Basic has come with many controls. By incorporating VBX controls into Visual Basic, Microsoft spawned the first commercially viable market for reusable

software component Component-based software engineering (CBSE), also called component-based development (CBD), is a branch of software engineering that emphasizes the separation of concerns with respect to the wide-ranging functionality available throughout a give ...

s. Third parties have created a large market of custom controls for resale. VBX components were called "custom controls" because the Microsoft development team envisioned them as visual "control" components like a toggle switch or button. Enterprising third party software component developers saw opportunities to use the VBX specification for non-visual components, such as components for creating ZIP files, manipulating low-level system settings and communicating with

TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

References

* https://web.archive.org/web/20091002232037/http://www.ascilite.org.au/ajet/ajet10/nelson.html {{compu-prog-stub Microsoft application programming interfaces