| Clipper | |
|---|---|
| Family | xBase |
| Developers | Nantucket Corporation Computer Associates |
| First appeared | 1985; 40 years ago (1985) |
| Final release | CA Clipper 5.3b / May 20, 1997; 28 years ago (1997-05-20) |
| OS | DOS |
| License | proprietary |
| Website | Last known Websitewww |
| Influenced by | |
| dBase | |
| Influenced | |
| Harbour | |
Clipper is anxBasecompiler that implements a variant of thexBase computerprogramming language. It is used to create or extend software programs that originally ran usually onDOS. Although it is a powerful general-purpose programming language, it was used mainly to createdatabase business programs.
One majordBase feature not implemented in Clipper is thedot-prompt (. prompt) interactive command set,[1] which was an important part of the original dBase implementation.
Clipper, from Nantucket Corp and laterComputer Associates, started out as a native code compiler for dBase III databases, and later evolved.[2]
Clipper 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 toComputer Associates for 190 million dollars and the product was renamed to CA-Clipper.[4][5]
Clipper was created as a replacementprogramming language forAshton Tate'sdBASE III, a very populardatabase language at the time. The advantage of Clipper over dBASE was that it could becompiled[6] andexecuted onDOS as astandalone application. In the years between 1985 and 1992, millions of Clipper applications were built, typically for small businesses dealing with databases concerning many aspects ofclient management andinventory management. For many smaller businesses, having a Clipper application designed to their specific needs was their first experience with software development. Also many applications forbanking andinsurance companies were developed, here especially in those cases where the application was considered too small to be developed and run on traditionalmainframes. In these environments Clipper also served as afront end for existing mainframe applications.[7]
As the product matured, it added elements of the programming languagesC andPascal, andobject-oriented programming (OOP), and the code-blockdata-type (hybridizing the concepts of dBasemacros, orstring-evaluation, andfunction pointers), to become far more powerful than the original. Nantucket's Aspen project later matured into theWindows native-code CA-Visual Objects compiler.[8]
Nantucket sold well in Western markets. Also, in November 1991, theNew 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).
In the early 1990s, under new ownership,[8] Clipper failed to transition fromDOS toWindows. As a result, almost no new commercial applications were written in Clipper after 1995.
By then, the "classically trained programmer" commonly usedstrong 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 wereVisual Basic,Microsoft Access,Delphi, andPowerbuilder. All provided strong typing.
The Clipper language is being actively implemented and extended by multiple organizations/vendors, likeXBase++ from Alaska Software andFlagShip, andfree (GPL-licensed) projects likeHarbour andxHarbour.[9]
Many of the current implementations are portable (DOS,Windows,Linux (32- and64-bit),Unix (32- and 64-bit), andmacOS), supporting many language extensions,[10] with much extendedruntime libraries, and various Replaceable Database Drivers (RDD) supporting many popular database formats, likeDBF, 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 standarddBase/xBase syntax, while also offering OOP approaches and target-based syntax such asSQLExecute().
The ClipperUsenetnewsgroups arecomp.lang.clipper andcomp.lang.clipper.visual-objects.
A simplehello world - application:
? "Hello World!"
A simple data base input mask:
USE Customer SHARED NEWclear@ 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->AddressREAD
The various Clipper versions, and release dates, were:
From Nantucket Corporation; the "seasonal versions", billed as "dBasecompilers":
From Nantucket Corporation; Clipper 5:
and fromComputer Associates; CA-Clipper 5:
After buying Nantucket, along with the standard Clipperlibrary, CA developed another, namedClipper 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.
a native code compiler for dBase ... later evolved ...
