Writing OS/2 REXX Programs
Description Of Chapters

This book contains the following chapters and appendices:

  1. Getting Started. Before you can write REXX programs, you need REXX installed, you need to know how to use an editor, you need to know how to run the programs and you need to know how to use the REXX help system. This chapter covers all those preliminary details. Experienced OS/2 users may want to skip this chapter.
  2. Language Overview. This chapter discusses the basic structure of a REXX program. You will learn the difference between a token, clause and statement and how these concepts interact with REXX. When you finish, you will understand more how REXX looks at your finished code to figure out how to execute it. If you are fairly new to REXX, you may want to skip this chapter and come back to it later after you have had more experience with REXX and are interested in learning more about its interworkings.
  3. Writing Simple Programs. This chapter introduces REXX programming by giving you a very quick tour of the power of the language.
  4. Interactive REXX. The program REXXTRY lets you enter REXX commands one at a time and see their results. Results even carry forward to future commands so a variable created with one command can be used by the next command. The program PMREXX lets you run REXX programs interactively and scroll through the results on the screen. Both make learning to use REXX and debugging REXX programs much easier. This chapter will explain how to use both programs.
  5. Introduction To Variables. OS/2 allows you to store information in variables and later use that information most any place that text or numbers would be used in a REXX program. This chapter will explain how to use variables.
  6. Communicating With The User. REXX includes commands to display information for the user to read and get information from the user. This chapter will explain how to use these features.
  7. Including Non-REXX Commands. REXX programs can run internal OS/2 commands, OS/2 batch files, other REXX programs and external programs in addition to running REXX commands. This chapter will explain how to include these in your REXX programs.
  8. Working With String. Unlike batch files, REXX has some very capable string processing features. This chapter will show the reader how to use these.
  9. Working With Numbers. Unlike batch files, REXX has moderate mathematical abilities. It's not the equal to C or Basic but it can add, subtract, multiply, divide and perform a few other operations. This chapter will show the user how to use mathematics in programs.
  10. Logic Testing And Looping. REXX includes the ability to perform advanced logic testing. Additionally, it has come very advanced looping features. This chapter will explain how to use these features.
  11. Built-In Functions. REXX has a number of built in functions. These functions perform common procedures-like finding the largest of a series of numbers or stripping off a substring. This chapter will explain how to use these functions.
  12. External Functions. The RexxUtil Dynamic Link Library adds a number of additional functions to the REXX language. This chapter will explain how to use these additional functions.
  13. Keyword Instructions. Prior chapters have introduced some of the REXX keywords. This chapter discusses the remaining keywords and briefly reviews those that have already been covered.
  14. Internal Subroutines. A subroutine is a REXX procedure that is called by another REXX procedure. An internal subroutine is one that is stored inside the main program. REXX has some very advanced subroutine abilities and this chapter will show you how to use these features.
  15. External Functions. Sometimes, there is are advantages to making a subroutine external to the program, in its own .CMD file. This is especially true when the subroutine is complex or when it can be accessed by several different programs. This chapter will you how to use external subroutines.
  16. Using The External Data Queue. REXX programs can perform a sort of advanced piping by pushing data into the input queue for other programs to pull out. This chapter will explain how to use this advanced feature.
  17. Condition Handling. This chapter describes how REXX programs can deal with the unexpected.
  18. Debugging. Occasionally, errors will creep into your programs. These errors are called bugs. This chapter will show you how you can spot these bugs so you can get rid of them.
  19. Glossary. This chapter defines common REXX terms used in the book.

Appendices

  1. Tables. This appendix is the tables for some of the programs discussed in the book.
  2. Programs On The Disk. This appendix documents all the programs that are included on the disk that comes with this book.
  3. Error Messages. This appendix will list the REXX error messages and explain what they mean.
  4. Icons. This disk that comes with this book includes a number of different icons you can use with the REXX programs you write. This book lists those icons.

 

 

© 2002 by Ronny Richardson, All Rights Reserved