Clipper is an xBase compiler that implements a variant of the xBase computer programming language. It is used to create or extend software programs that originally ran usually on DOS. Although it is a powerful general-purpose programming language, it was used mainly to create database business programs.
| Clipper | |
|---|---|
| Family | xBase |
| Developers | Nantucket Corporation Computer Associates |
| First?appeared | 1985 |
| Final release | CA Clipper 5.3b
/ May?20, 1997 |
| OS | DOS |
| License | proprietary |
| Website | Last known Website www |
| Influenced by | |
| dBase | |
| Influenced | |
| Harbour | |
One major dBase feature not implemented in Clipper is the dot-prompt (. prompt) interactive command set,[1] which was an important part of the original dBase implementation.
Clipper, from Nantucket Corp and later Computer Associates, started out as a native code compiler for dBase III databases, and later evolved.[2]
History
editClipper was created by Nantucket Corporation, a company that was started in 1984 by Barry ReBell (management) and Brian Russell (technical). Larry Heimendinger was Nantucket's president.[3] In 1992, the company was sold to Computer Associates for 190 million dollars and the product was renamed to CA-Clipper.[4][5]
Clipper was created as a replacement programming language for Ashton Tate's dBASE III, a very popular database language at the time. The advantage of Clipper over dBASE was that it could be compiled[6] and executed on DOS as a standalone application. In the years between 1985 and 1992, millions of Clipper applications were built, typically for small businesses dealing with databases concerning many aspects of client management and inventory management. For many smaller businesses, having a Clipper application designed to their specific needs was their first experience with software development. Also many applications for banking and insurance companies were developed, here especially in those cases where the application was considered too small to be developed and run on traditional mainframes. In these environments Clipper also served as a front end for existing mainframe applications.[7]
As the product matured, it added elements of the programming languages C and Pascal, and object-oriented programming (OOP), and the code-block data-type (hybridizing the concepts of dBase macros, or string-evaluation, and function pointers), to become far more powerful than the original. Nantucket's Aspen project later matured into the Windows native-code CA-Visual Objects compiler.[8]
Market penetration
editNantucket sold well in Western markets. Also, in November 1991, the New York Times reported the company's success in "painstakingly convincing Soviet software developers that buying is preferable to pirating". According to the article, Clipper had sold 2,000 copies in the Soviet Union[3] (compared to 250,000 worldwide).
Decline
editIn the early 1990s, under new ownership,[8] Clipper failed to transition from DOS to Windows. As a result, almost no new commercial applications were written in Clipper after 1995.
By then, the "classically trained programmer" commonly used strong typing, in contrast to the original dBASE language. An evolution of Clipper, named VO, added strong typing but made it optional, to remain compatible with existing code.[8] Four of the more important languages that took over from Clipper were Visual Basic, Microsoft Access, Delphi, and Powerbuilder. All provided strong typing.
Revival by third-parties
editThe Clipper language is being actively implemented and extended by multiple organizations/vendors, like XBase++ from Alaska Software and FlagShip, and free (GPL-licensed) projects like Harbour and xHarbour.[9]
Many of the current implementations are portable (DOS, Windows, Linux (32- and 64-bit), Unix (32- and 64-bit), and macOS), supporting many language extensions,[10] with much extended runtime libraries, and various Replaceable Database Drivers (RDD) supporting many popular database formats, like DBF, DBTNTX, DBFCDX (FoxPro, Apollo, Comix, and Advantage Database Server), MachSix (SIx Driver and Apollo), SQL, and more. These newer implementations all strive for full compatibility with the standard dBase/xBase syntax, while also offering OOP approaches and target-based syntax such as SQLExecute().
Usenet
editThe Clipper Usenet newsgroups are comp.lang.clipper and comp.lang.clipper.visual-objects.
?Programming in Clipper
editA simple hello world - application:
? "Hello World!"
A simple data base input mask:
USE Customer SHARED NEW clear @ 1, 0 SAY "CustNum" GET Customer->CustNum PICT "999999" VALID Customer->CustNum > 0 @ 3, 0 SAY "Contact" GET Customer->Contact VALID !empty(Customer->Contact) @ 4, 0 SAY "Address" GET Customer->Address READ
Version history
editThe various Clipper versions, and release dates, were:
From Nantucket Corporation; the "seasonal versions", billed as "dBase compilers":
- Nantucket Clipper Winter'84 – May 25, 1985
- Nantucket Clipper Summer'85 – 1985
- Nantucket Clipper Winter'85 – January 29, 1986
- Nantucket Clipper Autumn'86 – October 31, 1986
- Nantucket Clipper Summer'87 – December 21, 1987
From Nantucket Corporation; Clipper 5:
- Nantucket Clipper 5.00 – 1990
- Nantucket Clipper 5.01 – April 15, 1991
- Nantucket Clipper 5.01 Rev.129 – March 31, 1992
and from Computer Associates; CA-Clipper 5:
- CA Clipper 5.01a –
- CA Clipper 5.20 – February 15, 1993
- CA-Clipper 5.2a – March 15, 1993
- CA Clipper 5.2b – June 25, 1993
- CA-Clipper 5.2c – August 6, 1993
- CA Clipper 5.2d – March 25, 1994
- CA-Clipper 5.2e – February 7, 1995
- CA Clipper 5.30 – June 26, 1995
- CA Clipper 5.3a – May 20, 1996
- CA Clipper 5.3b – May 20, 1997
Clipper Tools
editAfter buying Nantucket, along with the standard Clipper library, CA developed another, named Clipper Tools. Three versions of this library were released, alongside Clipper versions. This library became a de facto standard among Clipper clones, such as xHarbour. It was also cloned by several of Clipper's clones.
References
edit- ^ Warren M. Littlefield (1983). DBASE - From the Dot Prompt: An Introduction to Structured Programming using dBase IV. ISBN?0791417808.
- ^ "Clipper".
a native code compiler for dBase ... later evolved ...
- ^ a b Rifkin, Glenn (3 November 1991). "Selling Software, Soviet-Style". The New York Times.
- ^ "CA-Clipper". Viva Clipper!. 14 September 2013.
- ^ GrafX Software licensed CA-Clipper in 2002 from CA for ongoing marketing and distribution.
- ^ Compiling dBASE code changes it from interpreted code, which must be interpreted every time each line of code is executed, to p-code, which uses a virtual machine to process the compiled p-code. p-code is considerably faster, but still not as fast as the machine code generated by native compilers. As a technical marketing ploy, the p-code was wrapped into object code (linkable .obj files) which gave the impression that it was compiled to native code.
- ^ "Clipper". thocp.net. The History Of Computing Project. 20 June 2007. Archived from the original on 12 May 2008. Retrieved 24 August 2016.
- ^ a b c da Silva, Rod (October 1, 1995). "Examining CA-Visual Objects". Dr. Dobb's Journal.
- ^ fbizzell (January 31, 2006). "Converting Clipper applications to windows".
- ^ "xHarbour.org". www.xharbour.org.
External links
edit- Free Open Source Graphic, GUI & Form Designer for CA-Clipper
- mini Clipper FAQ Archived 2025-08-14 at the Wayback Machine
- Print from Clipper to newest Windows printers article
- The Oasis is the largest file archive for CA-Clipper and xBase on the web
- Harbour Project A 32/64 bit multiplatform Clipper compiler
- CA-Clipper Website