Sams Teach Yourself REXX in 21 Days

Автор: WILLIAM F. & ESTHER SCHINDLER

Дата: 27.08.1994

"The best way to learn a programming language is through hands-on experience. With Teach Yourself REXX in 21 days, you'll move from beginner to expert in no time." states the first sentence on the back cover of the book. I would tend to agree that with this book, you could do quite well in REXX programming after finishing the entire book.

Although this book doesn't cover every aspect of REXX, it does cover the fundamentals quite well. You start off with the usual "Hello World" program that inhabits most programming type books in the first chapter, progressing quite thoroughly and rapidly forward. If you had just a few minutes to an hour each night, you would indeed take about 21 days to get through the book. If you have some exposure to programming, then you can finish this book in quite a bit less time (it took me about a week).

The book is laid out quite well, and if REXX takes off like it should, this would make for a good textbook in an educational environment. I like how the inside cover of the book is set up like a calendar letting you know what you will be covering on each "day". The example programs given in the book are "real world" type examples, and you will be using the small utility programs you create on a regular basis if you do a lot of REXX programming. There is a short Quiz and Q&A section, along with Exercises (don't skip these!) that will have you writing REXX code quite proficiently before you realize you are doing it.

One of the best parts of the book is the material in the back, such as converage of the VisPro REXX and VX-REXX tools, along with the IBM EWS Visual Rexx package. There is a bit on the Enhanced Editor (great for REXX programming), the future of REXX programming (Object REXX), a keyword and function reference and coverage of the Workplace Shell and how you can manipulate it with REXX.

The only drawback to this fine book, is the omission of a CDROM with demo versions of VX-REXX by Watcom, VisPro REXX by Hockware, the IBM EWS Visual REXX and demos of some of the other commercial REXX add-on packages out there. It would also be nice if the program listings, some Enhanced Editor macros, and different types of programming skeletons and samples that are available out on the Internet were located on the CD. This would make it almost a standalone development kit! There have been some additions to REXX since the release of OS/2 Warp that didn't make it into the book, but I hope that this book will be updated and re-released with some of these improvements to make it a true must-have for your programming shelf.

If you are considering learning programming for OS/2, REXX is the best place to start. You can learn the multithreaded programming model with REXX, along with named pipes and all the other fun stuff waiting for you in OS/2. Once you have mastered REXX, you will be able to build on to your knowledge by moving to other languages such as C/C++ or Smalltalk. Don't be surprised if you find yourself using REXX quite a bit after finishing with the book, since it will become an indespenseable part of your programming arsenal.

About the Authors

William F. (Bill) Schindler

William F. (Bill) Schindler is an independent consultant specializing in system software and optimization. He is coordinator of the OS/2 Special Interest Group of the Phoenix PC Users Group and Sysop of the two 20,000-member OS/2 Vendor Forums on CompuServe.

Esther Schindler

Esther Schindler is a computer consultant and Sysop of the ZiffNet Executives On-Line Forum. She is a contributing editor of Magazine.

WEEK 1 AT A GLANCE

You are about to begin your first week of learning how to program in REXX. We’ve written this book assuming that you’re going to write REXX programs using the OS/2 operating system. If you don’t have OS/2, you can still use this book; you just need to be aware that things may be little different on your system.

Before you can get started, you’re going to need an editor and the REXX interpreter. If you’re using OS/2, you should already have both of those items installed on your system. If you’re not using OS/2, you need to acquire these items. If you don’ have an editor or the REXX interpreter, you can still learn to program in REXX; you may feel like you’re learning to swim on dry land, though! Programming is a skill that is best learned by actually doing it. This book contains may REXX programs that give you, the new programmer, a chance to gain hands-on experience.

Each lesson in this book ends with a workshop that contains a quiz and exercises. At the end of each day, you should be able to answer the questions and complete the exercises. For the first days, we have supplied answers to all of the questions and exercises (see Appendix F, “Answers”). As you progress, we don’t supply answers for all the exercises because a variety of correct solutions is possible. Many of the exercises are also designed to produce useful utilities. Take advantage of the exercises and check your answers!

Where You’re Going…

The first week covers almost all the material you need to know in order to understand and write simple REXX programs. On Days 1, “Getting Started,” and 2, “REXX Ground Rules,” you learn how to create a REXX program and how to recognize the basic elements of REXX programs. Day 3, “Variables and Constants,” and Day 4, “Instructions, Expressions, and Operators,” take the concepts you learned in the first two days and expand on them so that you understand how the various elements covered on Day 2 fit together. Day 5, “Arithmetic,” provides information on how to do math in REXX. Day 6, “Executing System Commands,” covers using REXX to execute OS/2 system commands and developing REXX programs to replace batch files. Day 7, “Basic Input/Output,” wraps up the week with a discussion on writing programs that interact with users.

This information is a lot to cover in just one week, but you shouldn’t have any problems if you learn the information one lesson per day.

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