|AREXX Programming Tutorial Part 1 By CROW of The LOC NOTE : Please Note That All Examples Are Also Included So Than Can Be Executed Straight Away. What Is ARexx ? ARexx (pronounced A REX) is a programming language that anyone can learn! ARexx lets you write simple "scripts" (programs) that can define a task for the computer to perform. A script is just a text file containing a list of instructions that ARexx understands. Because of way ARexx can communicate with other programs running at the same time (thankyou multi-tasking), you can use MACROS written in ARexx that will work with specific software applications. You can also use ARexx programs to link operations of several programs to perform tasks that no one program can accomplish by itself. Origins of ARexx ? ARexx is so named because it is an implementation of the REXX language on the Amiga. REXX is a language definition developed over a number of years by Mike Cowlishaw at IBM. Cowlinshaw began in 1979 with the idea to create a language that was easy to program in and was designed for people, not machines. The language evolved as the newest versions were distributed over IBM's massive VNET network consisting of over 1000 mainframe installations. VNET users tested and used the lastest versions of the language sending suggestions and comments to Cowlishaw by electronic mail. The amount of testing and refinement that went on was staggering. On the system level the language was designed to be system independent, working on a variety of platforms and to be easily adaptable to future expansion. It was also designed with support for communicating with external "host environments", so that ARexx could be used as a standard macro language for operating systems, editors and other applications. In 1985 a version of ARexx was released for MS-DOS personnel computers. In 1987, REXX became the standard Procedures Language for all IBM systems Application Architecture (SAA) operating systems, which covers a large number of systems. William Hawes developed REXX for the Amiga as ARexx (Amiga REXX), Arexx built up a loyal following mainly in America, Commodore decided to include ARexx starting with version 2.0 of the Amigas operating system. Now most major applications support ARexx in some form; even though there has been hardly any large advertising of ARexx ot hype. But ARexx's popularity is attributed to the fact that most software developers had access too it and used and supported it in the products. Using ARexx Before you can run any ARexx scripts, the ARexx server must be actived, to do this run the program RexxMast, once this is running you are ready to run ARexx scripts (programs). When you run the RexxMast program the following text should be displayed (or something very similar) :- ARexx Version 1.15 Copyright (C) 1987 William S. Hawes All Rights Reserved If the above text is not displayed then you have done something wrong, such as RexxMast is not on the disk you thought it was or you are not in the Shell/CLI you have not switched your Amiga on or you are playing Impossible Mission 2025 (try the following password "EMPTYI " for last level !!!) smart game. If run RexxMast a second time you get the following extra line :- REXX server already active If you look on your Workbench Disk you will find a directory called rexxc (rexx commands) in this directory you will find the following programs. RXC - This removes ARexx server from memory. RX - Run a script or a given ARexx command. HI - Halts all executing ARexx scripts. TS - Starts interactive tracing. TE - Stops interactive tracing. TCO - Opens global tracing console. TCC - Closes global tracing console. RXSET - Set value for and ARexx clip. WaitForPort - Wait/Check for port message. RXLIB - Add a name to the Library List. The libraries that are required to use ARexx are :- rexxsyslib.library and rexxsupport.library, both of these libraries must be in the LIBS directory on your boot disk. The ARexx language is not case dependent like C is, so the following are all valid and treated the same :- say "hello" Say "hello" SAY "hello" Blank lines are treated as null statements; they are ignored. if you have learnt to program with some high level language such as Pascal or C, then you will find that ARexx is very easy to pickup. You have an advantage but to learn ARexx it is not really that important to know another language. A bit of an aside, I know the following high level languages Pascal, C, Pascal plus, Prolog, COBOL, Pascal with Objects, Visual Basic for Windows and also the following low level languages 680x0, 6502, 6510 (Big Head - Stone). Comments are started with /* and finish with */ so the three words and finish with, are a comment and are ignored by ARexx. /* Hello world in ARexx */ Say "Hello, World!" ARexx Operators ~ = Logical NOT + = Prefix conversion - = Prefix negation ** = Exponentiation * = Multiplication / = Division % = Integer division + = Addition - = Subtraction || = Concatenation == = Exact Equality ~== = Exact inequality = = Equality ~= = Inequality > = Greater then >=,~< = Greater than or equal < = Less than <=,~> = Less than or equal & = Logical AND | = Logical inclusive OR ^,&& = Logical exclusive OR Simple output and input ARexx scripts, example 1 to example 4. /* Example 1 */ Say "What Is Your Name : " Parse Pull name Say "Hello, " name /* Example 2 */ a = 10 b = 20 Say "10 + 20 = " a + b /* Example 3 */ a = 20 b = 30 c = a + b Say "20 + 30 = " c /* Example 4 */ Say "Enter Number 1 : " Parse Pull a Say "Enter Number 2 : " Parse Pull b c = a + b Say "Number 1 : " a " + Number 2 : " b " = " c Compound statements (If's and Loops) /* Example 5 */ Do 10 Say "Hello" End Output : Hello Hello Etc.. /* Example 6 */ a = 10 Do a Say "Line : " a /* Each Line = " Line = 10 " End Output : Line : 10 Line : 10 Etc... /* Example 7 */ a = 10 b = 1 Do a Say "Line : "b b = b + 1 End Output : Line : 1 Line : 2 Etc... /* Example 8 */ Say "Enter Age : " Parse Pull num If num > 21 Then Say "Hello, Crusty" Else Say "Hello, Child" /* Example 9 */ Say "Enter Name : " Parse Pull name If upper(name) = 'CROW' Then Say "Yeahhhh, Hello Matey !!!" Else Say "Ohhh, Hello " name /* Example 10 */ Say "Enter Group Name : " Parse Pull gname gname = upper(gname) /* Up Case All Characters */ Select When gname = "LSD " Then Say "Grapevine is the Best." When gname = "THE LOC" Then Do Say "Erotic Stories 5 ECS" Say "and AGA Versions Out Now !!" End When gname = "SCOOPEX " Then Say "Bag Of Shite Of A Group !!!" Otherwise Say "Which Group Is That Sorry ???" End I hope the above examples with aid you in learning ARexx, the best way to learn a language is to play with it and build up your knowledge of what different functions and procedure do. You will find examples 1 to 10 as ready to run programs on one of the Grapevine disks. Extracts for the article are taken from the book - Using ARexx On The Amiga which is published by Abacus, I would recommend this book to anyone who wants to delve into using ARexx as it is one hell of a useful language. end.