Games - ARexx

	Games - ARexx

ARexx is the Amiga version of scripting language REXX by IBM. It is not a version licensed from IBM, but is a version written by Bill Hawes who ported REXX to the Amiga, with many special Amiga features.

Technically speaking ARexx is an interpreted language for scripting. This means it should be already active in memory in order to "interpret and run" any program loaded by the users.

A program written in this language (called either a "script" or a "macro") could be applied to expand features and functionality of an Operating System or also to increase the features and capabilities of a productivity program (an application).

Because of its ease of use ARexx is strongly recommended for learning fundamental programming techniques. Because of its simplicity ARexx also has a place in the hearts of experienced programmers because many use ARexx due to its flexibility and integration with the AmigaOS.

End users of a productivity program also find in ARexx a valuable tool which can help them in personalizing their work environment.

ARexx is also useful in exchanging data and files between programs in order to take advantage of features that are present in one application and absent in another, or even to "borrow" a feature from a program while using another one.

Finally, the end user could also benefit of the capability of ARexx to build automated macros to perform scheduled work even in his or her absence and to avoid repetitive procedures.

History

ARexx was born in 1987, being developed for the Amiga by William Hawes. It is based on the REXX language described by Mike Cowlishaw in the book "The REXX Language: A Practical Approach to Programming", published by Prentice-Hall in 1985. Programmers and users evaluated it positively and responded to the enormous success of this script language in the Amiga scene. So ARexx was included by Commodore into AmigaOS 2.0 in 1990. It follows official REXX language closely (Hawes was later involved in drafting the ANSI standard for REXX).

Almost any modern Amiga program has currently an ARexx port and could exchange data with other programs or use ARexx to automate its internal functions and procedures. Even the Workbench graphical user interface (GUI) of Amiga shares an ARexx port, and the commands of AmigaDOS have a strong compatibility with ARexx.

Development of ARexx has stopped because ARexx is written in 680x0 Assembly and must be rewritten in order to function properly with new PPC CPUs. Also William Hawes is no longer involved in development of Amiga programs because of quarrels in the past with Commodore, Inc. about the licensing of ARexx. Further, there is no Amiga-related firm interested in financing new versions of ARexx. Notwithstanding this fact the existing version of ARexx performs flawlessly and has no major bugs, so none has yet upgraded it.

More recently Amiga programmers and users have had good experiences with Python programming language. Python is increasingly catching the interest of the Amiga community and is one of the major candidates in succeeding ARexx as integrated language for scripting and expanding the functions of the AmigaOS environment.

Characteristics

ARexx is a programming language that can communicate with other applications. Using ARexx, for example, one could request data from a database application and send it to a spreadsheet application. To support this facility, an application must be "ARexx compatible" by being able to receive commands from ARexx and execute them. A database program might have commands to search for, retrieve, and save data. MicroFiche Filer is an example of a database program with an extensive ARexx command set. A text editor might have ARexx commands corresponding to its editing command set. For example, The Textra editor supplied with JForth has an extensive ARexx command set, which can be used with JForth to provide an 'integrated programming environment'. AmigaVision, the multimedia presentation program, also has ARexx port built in and can control other programs using ARexx.

ARexx can increase the power of a computer by combining the capabilities of various programs. Because of the wide acceptance of ARexx, Commodore includes it with Version 2.0 of AmigaDOS. If you are an Amiga programmer who is developing an application, it is highly recommended that you provide ARexx compatibility, if appropriate, by inserting an ARexx port in your program.

ARexx uses "typeless" data representation. Other programming languages made distinctions between integers, floating point numbers, strings, characters, vectors, etcetera. In contrast, ARexx deals with all data as strings of characters, making it simpler to write expressions and algorithms. It is not necessary to declare a variable before using it. This feature is typical in a large number of interpreted languages, i.e., the languages in which dynamic data (data that exist during program execution) is handled directly by the interpreter.

[ Visit the complete Wikipedia entry for ARexx ]

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