Clipper (programming language)

Clipper
First appeared 1985 (1985)
Stable release
CA Clipper 5.3b / May 20, 1997
OS DOS
Website www.grafxsoft.com/clipper.htm

Clipper is a xBase compiler, which is a computer programming language, that is used to create software programs that originally operated primarily under DOS. Although it is a powerful general-purpose programming language, it was primarily used to create database/business programs.

History

Clipper was created by Nantucket Corporation, a company that was started in 1984 by Barry ReBell (management) and Brian Russell (technical). In 1992, the company was sold to Computer Associates for 190 million dollars and the product was renamed to CA-Clipper.[1][2]

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[3] and executed under MS-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 a lot of 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.[4]

As the product matured, it remained a DOS tool for many years, but added elements of the C programming language and Pascal programming language, as well as 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 Visual Objects compiler.

Despite these efforts in the early nineties under its new ownership Clipper proved to be unable to make a smooth transition from the MS-DOS to the MS-Windows-area. As a result, almost no new commercial applications were written in Clipper after 1995. Three of the more important languages that took over from Clipper were Visual Basic, Delphi and Powerbuilder. Some existing Clipper applications continued in use for ten or fifteen years, requiring regular maintenance, but around 2015 the number of Clipper applications that were still used commercially on a daily basis, was very small.

The Clipper language is being actively implemented and extended by multiple organizations/vendors, like XBase++ from Alaska Software and FlagShip, as well as free (GPL-licensed) projects like Harbour and xHarbour.

Many of the current implementations are portable (DOS, Windows, Linux (32- and 64-bit), Unix (32- and 64-bit), and Mac OS X), supporting many language extensions,[5] and have greatly extended runtime libraries, as well as 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().

The Clipper Usenet newsgroups are comp.lang.clipper and comp.lang.clipper.visual-objects.

Compiling and running hello world program in clipper

Programming in Clipper

A 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

The various versions of Clipper were

From Nantucket Corporation; the "seasonal versions", billed as "dBase compilers"

From Nantucket Corporation; Clipper 5

and from Computer Associates; CA-Clipper 5

References

  1. ↑ https://vivaclipper.wordpress.com/tag/ca-clipper/
  2. ↑ GrafX Software licensed CA-Clipper in 2002 from CA for ongoing marketing and distribution.
  3. ↑ 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.
  4. ↑ History article concerning Clipper.
  5. ↑ "xHarbour Language Extensions".

External links

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