• Guru: Global Variables in Modules

  December 13, 2021 Ted Holt

  When I first learned to program computers (RPG II, COBOL 74), the only kind of variables I knew of were global variables. Any statement within a program was able to use any variable.  It was not until I started my computer science degree that I found out about local variables, which are known to only part of a program. Since that time, it has been my practice to use local variables as much as possible and global variables only when necessary.

  Ideally an RPG program, service program, module, or subprocedure would have no global variables at all, but I don’t …

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• The Four Hundred Guru Retires

  December 13, 2021 Ted Holt

  This is the last issue of The Four Hundred for which I am serving as technical editor.

  I have been editing the technical content of and writing articles for this august publication for 20 years. For most of that time, this has been a side job that I’ve done outside of normal working hours (i.e., nights and weekends). I’m ready for a change. Technical editing and writing are not easy and they take a lot of time, time that I had rather spend doing other things.

  In the days ahead I plan to spend:

  • Less time sitting and more time

  …

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• Guru: RDi 9.6, Part 12 – New Features Targeting New RDi Users

  December 6, 2021 Susan Gantner

  In my previous tip about the latest release (9.6.0.11) of RDi, I promised to cover new features targeting easing the transition from PDM/SEU for new RDi users. If you’re an experienced RDi user, don’t tune out yet — you may find something of interest, too.

  I’ll discuss most of these features in the context of the PDM perspective. This is the perspective designed specifically to ease the transition to RDi. It was introduced originally back in 9.6.0.3 and I covered a little about it in a tip back then. While it was created to target new users, it seems …

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• Guru: Content Assist Plus in Run SQL Scripts

  November 29, 2021 Paul Tuohy

  By now, you should be well aware that Run SQL Scripts provides content assist (promoting) for Select statements (see Guru: ACS 1.1.8.3 Content Assist Includes Prompt For SQL! ). But did you know that you can also use content assist for stored procedures, table functions and parameters? Let’s see how it works, using some of the Integrated File System (IFS) procedures and functions provided by IBM i Services.

  Prompting a Stored Procedure

  Open Run SQL Scripts, type in:

  call qsys2.
  

  Then press F4 (or Ctrl+Space). You will be presented with a list of all the stored procedures in the schema …

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• Guru: Physical System Performance

  November 15, 2021 Dawn May

  Almost all IBM i shops use logical partitioning and have several partitions on a single Powerbox. There may be several IBM i partitions, VIOS partitions, and possibly AIX or Linux on Power partitions. Regardless of what type of operating system is running in the partition, the hypervisor collects performance metrics for all partitions. These performance metrics are always being collected, and you can allow a partition access to these performance metrics. In the case of IBM i, this physical system performance data can be gathered by Collection Services. IBM documents this feature in Collecting and displaying CPU utilization for all …

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• Guru: Abstract Data Types and RPG

  November 8, 2021 Ted Holt

  An abstract data type (ADT) is a type of data and a set of operations defined over that type of data. Using ADTs allows a programmer to work with data in terms of functionality rather than physical representation. The ADT is the basis of object-oriented programming. Does that mean that abstract data types don’t apply to procedural languages like RPG? Not at all. Quite the contrary.

  Before I show you how you can use abstract data types in RPG-based applications, let me further illustrate abstract data types with another, non-OO object — the user profile. The user profile is a …

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• Guru: Flexible Interfaces

  November 1, 2021 Ted Holt

  The details are murky, it’s been eons ago. Probably the mid-1990’s. I was working on an AS/400 that ran a mixture of System/36 and native applications. I needed to call a program that had been written in the latest version of RPG from both S/36 RPG II and native RPG III (a.k.a. RPG/400) programs. I hope I’m remembering this correctly. It’s been so long.

  The problem I ran into was rooted in a numeric parameter. S/36 programs passed numeric parameters in zoned decimal format, whereas native RPG and CL programs used packed decimal. The called program defined the parameter as …

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• Guru: Quick And Handy RPG Output, Take 2

  October 25, 2021 Ted Holt

  I am pleased today to revisit a topic I wrote about just over seven and a half years ago. I do so for two reasons. First, I’ve made a slight improvement to my routine. Second, I’d like to provide more examples of this routine in action. My previous article suffered from a paucity of examples. I can’t believe I let that happen.

  I’m talking about the writeln subprocedure, a handy routine that I use to write unstructured text to a spooled file. I derived the inspiration for this routine from Pascal, a programming language I used heavily when I was …

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• Guru: What Is Constant Folding And Why Should I Care About It?

  October 18, 2021 Ted Holt

  Constant folding is a compiler-optimization technique, whereby the compiler replaces calculations that involve constants with the result values when possible. Constant folding is common in modern compilers, and according to the RPG reference, the RPG compiler uses this technique. (See the documentation of the %div and %rem functions, for example.)

  But you and I don’t write compilers. We write business applications. Why then should we care about constant folding? That’s a question worth pondering.

  Consider how I used to have to write RPG in the Dark Ages.

  C                     MOVE CUSTNR    CUSTSV  50
  

  Here I’m copying the customer account number to …

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• Guru: Fall Brings New RPG Features (And So Did Spring!)

  October 4, 2021 Jon Paris

  When I first sat down to write this tip my focus was on introducing you to the new RPG features that were added alongside the latest September Technology Refresh (TR). However, when I tried to reference one of the enhancements from the spring enhancements, I quickly discovered that I had never written those up for the Guru column!

  Oooopppps! As a result, this “tip” will cover all the RPG enhancements added this year, both in the April and September announcements. It will be in two parts. This first part will cover the array-oriented features.

  RPG’s range of array-processing options has …

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