RPG and Programming

But sometimes, to old codgers like me, it’s difficult to know just how far to go. In previous posts I have written about my vaguely negative feelings about freeform RPG, and I have written very clearly about how I feel about IBM’s unwillingness to implement the MOVE instruction in freeform RPG, pointing out how this can only hinder conversion of old code and diminish acceptance of the new RPG dialect.

Case in point, a program I was working on today. I was writing code to implement formatting of a six-digit account number based upon the rightmost 6 digits of an 11-digit number. It was based upon some old code (the usual situation where I work), but the old code was hideous. The old program consisted of about 15 lines of MOVE and MOVEL statements. I said, this has got to go.

So I contemplated the best way to do it. I could set up a data structure and put pieces of the account number into that, using EVALs or MOVEs,with dashes embedded as needed. But that didn’t seem quite elegant enough. I have been working harder to modernize my own code, so I finally broke it down to these two possibilities, as illustrated in this test program. The result I am aiming for is the number formatted as 01-234-5.

     H DFTACTGRP(*NO)   ACTGRP(*CALLER)
     D BACTNO          S             11  0 INZ(99999012345)
     D ACC6            S              8    INZ(*BLANKS)
     D NUM6            S              6  0 INZ(0)
     D ACCW            C                   '0  -   - '
     C/FREE
       EVALR ACC6 = %EDITW(%DEC(%SUBST(%EDITC(BACTNO:'X'):6:6):6:0):ACCW);
      /END-FREE
     C                   MOVE      BACTNO        NUM6
     C                   EVALR     ACC6 = %EDITW(NUM6:ACCW)
     C                   EVAL      *INLR= *ON

One way mixes the old and the new, with an old-fashioned MOVE to the smaller field, followed by a new-fangled %EDITW BIF using a predefined edit word. The other goes full-bore new age, with one grand set of embedded functions. To get the 11 digit number in string form so I can substring it, I use %EDITC with an X edit code, which does the conversion. Next, I %SUBST (substring) the last six characters. I then use %DEC to convert those six characters back to numeric. Finally, I apply the %EDITW function to format those six digits as desired. (I would be interested in finding out about a shorter way to do it.)

But I have a problem with it. In an earlier post, I pointed out that the ability to create long, complex functions in freeform is not necessarily a virtue. The mere fact that I felt the need to explain it here indicates that I am not comfortable with it. The code is short, but I do not feel that it is clear. On the other hand, while the the two-line version using MOVE is short and sweet, and uses a BIF, it would force me to get out of freeform to use the MOVE; stylistically, that also seems wanting.

Since the thrust of my thinking is in trying to modernize the code so future generations of converted C programmers won’t be freaked out by the C in column 6, I am leaning toward the one-line version. But I don’t like it. It’s ugly.

I was going to discourse on another topic, but a response to Buck (to whom I apologize, along with Bill, for being derelict in checking my site’s e-mail), who commented on my previous post, demands a reply. He feels that lack of formal education, while being a contributing factor, is only a contributing factor; rather, it is the midrange habit of being exposed to one programming language.

Actually, I am inclined to agree. The isolation in RPG is real. But we also do well to consider the background of the situation. The earliest IBM minicomputers, the System/3, had as its programming language RPG II. That was it. Small businesses who wanted that computer worked in that language- at least, I’m not aware of others used on the machine, besides assembler.

When the System/34 came out in 1977, the choice of compilers widened. BASIC, COBOL, and Fortran became available. But still, RPG dominated. I’m not surprised that Fortran and BASIC popularity did not rise. But COBOL was big at the time. However, RPG was already a business-oriented language, so COBOL was not really needed from that standpoint, and RPG was perhaps felt to be more terse and easier to learn. Then too, COBOL programmers were already being kept busy keeping the IBM mainframes humming, so there were probably not an excess of them floating around. COBOL has never been much more than a peripheral language on the IBM midrange; useful probably only to those whose business already depended in some way on COBOL, perhaps having COBOL talent already available.

In addition, and perhaps most important of all, The System/34 had no need to talk to the outside world unless it were to another IBM minicomputer or mainframe. There was no need to handle HTML; there was no HTML, because there was no Internet.

This is not to say that RPG was a perfect language. String manipulation beyond the realm of MOVE and MOVEL was very difficult. The two things the designers never got right until RPGIV came along were string manipulation and date arithmetic- being able to get the date 30 days after today, for instance. (One thing I will never comprehend is why they have never been able to enable multiple dimension arrays. In earlier days in a different environment, trying to emulate multiple dimension arrays was a real pain.)

But since the programmers had no other languages to work with, they bent RPG to their will. They created these plug-ugly array- manipulation routines to piece together strings. And they created complex routines to do date addition and date format conversion. We must not forget the famous “magic numbers” - to convert a date in month-day-year for mat to year-month-day, for instance:

MMDDYY MULT 10000.01 YYMMDD. I am still reminded of the RPG programmer of my acquaintance who, with the help of engineers, created sines and cosines and other functions in RPGII.

Now, there may have been elegant functions created in C for such purposes as string manipulation and mathematical functions. But once RPG routines were developed, the C functions were not needed. It really didn’t matter. They couldn’t use C anyway. If you knew what you were doing, you could write assembler subroutines – but that was it. I don’t think RPG couldn’t even call COBOL programs; at least the techniques were not well known for doing so.

So when ILE came around, much of the motivation for calling the now-available C routines was missing. We didn’t need them. RPG routines were already doing the work. Unless there were some performance considerations, programming managers would probably take a dim view of programmers who ripped out the ugly-but-tried-and-true RPG routines just for their own amusement. One could make a valid argument that those routines were a maintenance nightmare. But unless management had a good deal of foresight, this might be a difficult thing to prove to management’s satisfaction.

And yes, programmer inertia was also a factor. My shop has had IBM midrange machines since the 1970’s, and AS/400s since the 90’s. But the first RPGIV program was written on this system in 2007, by me after I arrived.

But now, the IBM midrange does have to deal with the outside world. My company already has an Internet presence, and we quite frankly don’t have to know PHP or Java or the other languages in vogue in order to make the business work. All we have to do is make sure our Internet provider gets the necessary data. And RPGIV provides the necessary tools to alleviate some of the issues that plagued us with earlier versions of RPG. If we need outside routines like APIs or C or Java or Rexx, they are easy enough to call. I have expressed myself in earlier posts about my ambivalent feelings about freeform RPG.

But mentioning freeform brings us to the topic of: How do our employers find replacements for us fixed-format loving old codgers when we retire? That is a topic for another time.

I have been thinking a bit about how our backgrounds, educational and otherwise, may determine at least to some extent the style we use in our programming and indeed perhaps the language we use.

One of my fellow programmers (about my age) graduated from college with a background in computers. Almost immediately he was able to find a position programming in COBOL, then in ALGOL, which is a block-structured language with a relatively free format. He continued to do well at various positions; ultimately, he came to where I work, with many years of experience in programming, but none in RPG. The style here could be described as a blend of RPGII, RPGIII, and RPG/400; fixed format to the core, loaded with indicators. He learned RPG from the ground up in that environment. Sometime after I came along, he was shown freeform RPG.

I, on the other hand learned RPGII from a book and practical experience. I had no computer background when I started to learn. I was of an inquisitive spirit, though, and I advanced in my use of RPG as the language itself improved. I too ultimately became acquainted with freeform RPG.

Now, who do you think uses freeform RPG whenever he can, especially on new programs? You might have guessed it was my partner- if you did, you’d be right. RPG was actually stifling to him; given the freedom to use free format RPG along with the BIFs that work well with it, he has been liberated. On the other hand, as you may judge from this blog, I just have not seen the light or the point. When I write code for new programs, it is in fixed format RPGIV.

We learned to love the way we learned programming, and so our preference now is to do it the way have always learned it, just better.

Illustrating the point that the way we learn to program is greatly influenced by our programming origins was a discussion I just read on an RPG forum about the significance of certain characters when writing CL (Control Language on the AS/400). Instead of indicating a “not equal” test by the common expression *NE, the code used the combination ^=, where the ^ is really a character I can’t find on my keyboard, but looks like the upper-right-hand corner of a rectangle with the top leg longer than the right. The character, as it turns out, is the “logical not”, a character often used in Boolean algebra.

Now, I don’t know who originated that code. Some experienced programmers, though, just did not know what it meant. Therein may lie a tale.

During the time I learned, many if not most of my fellow programmers were not products of any kind of computer science curriculum. They did not learn BASIC or Fortran first, and usually not COBOL, though this was a bit more common. They learned RPG as their first language. They did not learn “computer science concepts”; many, like me, either never attended college or did so only briefly. They may have started as a computer operator, or maybe at another position in their company. Usually it was a small company; it had the smallest capacity IBM computer available, the System/3, or System/32, or System/34. Something about the programming process intrigued or excited them; they persevered, and they advanced.

As time went on, though, and RPG increased in importance, people with a background in computers and computer science began to program RPG. For a long time, they would prove to be stifled if they expected to program like they originally learned to program in other languages. And where the original programmers may have simply accepted, for example, the RPG cycle, and comprehended it entirely, by the time the System/38 came around, programmers who started learning RPG as RPGIII on the System/38 evidently found it mind-boggling.

I can’t count the number of times I have found a test for LR (last record) in the RPG detail cycle in code (usually written by programmers who came from the 38) using an input or update primary file. Unless explicitly set on with a SETON instruction, the LR indicator will never be on during the detail cycle. A programmer who started with RPG II would automatically know this – it would be a part of his upbringing. A programmer who started with a background in computers later would not necessarily know this. This would cause problems if the programmer intended to base output on this indicator test. Usually it would mean that last record calculations and total output would be missing.

Another difference in outlook comes with file processing. A programmer raised on RPGII (usually in a small shop) doesn’t mind the system reading files (primary and secondary) without him telling it to. But I have noticed in discussion forums that people raised on other programming languages (usually learned in college) seem to get bent out of shape if they don’t explicitly get to do the file reading themselves. They don’t really comprehend that this really is quite an advanced feature, much closer to SQL than Pascal.

It would be interesting to find a survey of programmers that told what level of education they had when they first started programming professionally. I would suspect that as a group, RPG programmers would have a slightly lower level of educational advancement than, say, a C or Java programmer. This would especially be true if they surveyed the most experienced RPG programmers. But then, it is results that matter. RPG programmers do not write compilers – we process information so that humans may comprehend it.

The rather slow acceptance of freeform RPG since its inception has been intriguing to me. For that reason, a recent discussion on  the RPGIV forum has been interesting. Bob Cozzi, a well-known RPG expert, posed a question about how long it took to actually code the implementation of freeform to Hans Boldt, who evidently was on the team at IBM that developed the original implementation.
Hans said that it only took about 1 PM (person month?) to actually code it, but considerably more time was spent in planning. I can believe this. The planning discussions must have been particularly interesting.
One of the biggest things that have slowed acceptance of freeform was the non-implementation of MOVE and MOVEL. This is also the opinion of Cozzi and others in the field. Mr. Boldt touched on this and other issues.
Boldt’s first design included implementation of all opcodes. Others in the group, one in particular, argued vociferously against it. Boldt eventually came around to their way of thinking. As he said, “That design point meant we didn’t have to worry about those goofy multi-part factors.”  (I’m not clear on what that means, exactly. But anyway…..)
Once that was established it was just a matter of deciding which to implement and which not. GOTO was thrown out because, as stated in Nicklaus Wirth’s famous title for Edsger Dijkstra’s article on GOTO, “Go To Statement Considered Harmful”. I could quibble about that, but since it’s been probably 4 or 5 years since I last put a GOTO in a program, there wouldn’t be much point in arguing.
With MOVEL and MOVE however, Mr. Boldt doesn’t understand why people are so attached to those opcodes. He says, “It’s hard to see how these opcodes can be missed given the other options available by free-form opcodes.”
To a certain extent, I agree with his comments. I myself have used MOVE/MOVEL very seldom in the last several years. New opcodes have for the most part been very workable. Using EVAL and many BIFs, I get along very nicely. When EVAL gets a little tedious, I often create data structures to put together data in the desired patterns.
The problem is, I am talking about new code. Old code from the 70’s, 80’s and early 90’s did not have all this neat stuff available. About all you had for data manipulation was MOVE and MOVEL, along with their cousin MOVEA, along with perhaps data structures. From my observations over the years, I would say most programmers did not avail themselves of the help even data structures could provide; they did their work with MOVE(L). We are not talking about an easily disposable opcode like FORCE; we are talking about opcodes that appeared in almost every non-trivial RPG program before RPGIV, and most of the trivial ones. They used the opcodes to change data types (from alphanumeric to numeric and back). Above all, they used MOVE to manipulate strings, piecing together long strings from five or six (or more) smaller ones. One can complain that this is a very kludgy way of doing things, but this is all we had to work with. I would suspect that there are millions, if not tens of millions, of MOVEs in the legacy code sitting on today’s AS/400s (or whatever we’re supposed to be calling them today).
So what do we do in freeform once MOVE is taken away from us? As pointed out in the post I referenced yesterday or the day before, we must choose among 10 or 15 alternatives, depending on what we want to do - which in a sense is a demonstration of the power of the opcode. There is no easy conversion; it is not the same thing as changing  KEY   CHAIN    MASTER  to CHAIN KEY MASTER; . I don’t think even artificial intelligence could do even close to a good job of determining the best conversion; Linoma tried, but some MOVEs are just untranslatable without human eyes and brains to analyze them.
Therein lies the problem. If you rule out MOVE in freeform, a human must determine the best way to translate it to freeform. It simply isn’t financially practical to spend resources changing massive amounts of fixed-format code to freeform by hand, and the utilities available for automatic conversion do not do a clean job. You can use Linoma’s software; you can use Websphere’s conversion facility, which does not handle the MOVE and does not even attempt to do the indentation; there may be other utilities around. In the end, to convert legacy code, you can convert it to a degree automatically, but you will still be left with MOVEs to contend with by hand. You end up with ugly flipflops between free and fixed format that may even be harder to read and deal with than the original fixed format code.
It is very nice to say, that when we modify a program, we will also change it to freeform. But that is a slow way of converting what might be hundreds, or even thousands, of programs on your system. Remember, converting a MOVE to something else is not the same as reformatting a CHAIN; it must be carefully tested.
So, while freeform may ultimately win out, it could have been done a lot more readily if MOVE had been implemented in freeform. The more I think about it, I wonder if someone’s ego got in the way, someone who said, “I am going to teach these plebeians how programming SHOULD be done, instead of using these operations that no other reputable programming language uses.”  (Down, XFOOT, down!!!  Don’t bite him!)
And to think it could have been avoided by allowing the conversion of  MOVE  STRING1   STRING2  to the freeform equivalent:  move   string1    string2.

I didn’t think I’d be considering free-format RPG so soon as a final solution for the current RPG programs on the system at work (some of which date back to the 70’s), but a number of interesting events have taken place.
Our IBM representative made us aware of a software package that accomplishes the conversion of RPGII, RPGIII, and RPG400 programs into true RPGIV. This means (among other things) ditching the left-hand indicators and attempting to really use more modern operation codes. If you are at all familiar with what would be necessary, you can appreciate how difficult this task would be without some kind of automation. The painstaking code changes and testing would be incredible on a code base of any size.
This package is called RPG Toolbox, from Linoma Software.
So we downloaded the trial version, which allows 10 source conversions from another RPG dialect - or even RPGIV that has simply been converted from an older format using IBM’s CVTRPGSRC utility. CVTRPGSRC simply reformats old code into RPGIV syntax; it does not attempt to modernize it. We converted a source member with a lot of left-hand indicators, and we were impressed how it converted into a reasonably neat format without those indicators. What really impressed me was that it would attempt to convert a series of MOVE statements, which was commonly the method used to piece together larger fields, into EVAL statements. This could be a dangerous technique, but the RPG Toolbox utility carefully analyzes the code to make sure it is safe. In the manual, it describes how it makes decisions about code conversion; if one is interested in this product, that person would do well to download and read the manual before making decisions about what the program should do in the course of conversion.
I also had an inspiration- why not use it to convert RPG IV to freeform? In earlier posts, I have declared my reservations about how valuable freeform is. But, if it’s easy, why not live dangerously? So I tried converting one of the RPGIV programs in my file cross-reference system to freeform. The results were impressive. It looked VERY good. The more I looked at it, the more I liked it. So I said to myself, why not convert ALL our code to freeform?
But then my younger cohort brought me back down to earth. He wasn’t so sure that would be a good idea. So we converted the old-format code referred to above into freeform. The results were messy. There was much code that simply could not be converted, often involving the MOVE and MOVEL opcodes. (I have also commented on this previously.) When this happens, the free-format code is enclosed in a /FREE - /END-FREE set of compiler directives and the code drops back into fixed format. Switching back and forth between free and fixed can be maddeningly ugly.
So I have backed off the idea of a total conversion to freeform RPG. But we still feel that converting our code to a clean RPGIV that uses as much as possible of RPGIV’s modern syntax and opcodes would certainly be a good thing; and it appears that it would be relatively safe. We have ordered the software. Where the conversion of a program to freeform would not create too messy a result, we can still convert it.
I was also surprised to learn how quickly the most experienced one on our crew would take to freeform. He first started programming in ALGOL; so freeform is not really that much of a leap for him. He has in the past several weeks written new programs in freeform RPG, of his own free will. My other partner has a Pascal/Java background; so freeform would come “naturally” to him. I am the one who will take some getting used to the idea.

I work on code that, when I came to work for my client, was essentially RPGIII/RPG400 or older. Some of the code had been implemented way back in the 1970’s and was migrated forward as newer machines were installed. And the code showed it. (I have found interesting the large number of 80 and 96 byte files in some of the systems, remnants of old punchcard processing programs.) You haven’t lived until you’ve attempted to update a program that has grown over the years to be a 10000+ line, indicator-laden monster. If you’ve been away from the program awhile and you need to make a non-trivial change, you need to spend part of a day, at least, reviewing the program’s processing.

I am normally conservative about program changes. I generally do not rip apart code and rewrite it, especially if it is not broken. But if a program is to be revised, I do generally at least convert it to RPGIV before making even a minor change. As a phrase used by one of my favorite literary characters (Anne of Green Gables) says, doing this allows “more scope for imagination”.

I was making code changes for a conversion project I was working on when I came across a particular program I had seen before and shook my head at. But for some reason, this time something snapped. I just HAD to change a particular chunk of code, even though the code in fact worked. No errors. But how far to change it? I will explain what I did. In the end, what I do will likely be seen as good by some, too intrusive by others, and  not radical enough by still others.

(more…)

One of the more interesting things about freeform RPG, at least currently, is its support of the MOVE/MOVEL RPG operation codes. It doesn’t.
For those not so familiar with RPG, MOVE (move right) and MOVEL (move left) are codes that you will find in almost any standard RPG program. What do you do with them?
You can:
1. Move a string into another string. If the target string is smaller, the move ends with the filling of the string. For example, assuming the field MONTH as a 9-long string with value “NOVEMBER” and a 5-long string RESULT:  MOVE MONTH RESULT results in ‘MBER ‘ ; MOVEL MONTH RESULT result is ‘NOVEM’. If the smaller field is MOVEd to the larger, what is left remains unchanged (unless the move is given a code (p) which causes it to be filled with blanks). If RESULT was ‘NOVEM’, MOVEL ‘123′ RESULT would produce ‘123EM’
2. You can MOVE strings to numeric fields, and strings to numbers. In this case, the system will try to convert the string to numbers; this is no problem, especially if the string is already a number.
3. Move strings and numbers to DATE type fields (which RPG can manipulate with other techniques, such as adding a month to the date), and vice versa.
In fact, 14 pages in the RPGIV manual is devoted to examples of how to use the MOVE opcode. (As we said above, MOVEL just starts from the left. Almost as many pages are given to MOVEL).
You would think at first that IBM would want to use this code, in view of its widespread use and of its power. Syntax would not be an issue; I deliberately did not attempt to put my example above in fixed format, just to show how obvious the syntax was.
But, what does the IBM manual say about MOVE? To quote:
“Free-Form Syntax: (not allowed - use the EVAL or EVALR operations, or built-in functions such as
%CHAR, %DATE, %DEC , %DECH, %GRAPH, %INT, %INTH, %TIME,
%TIMESTAMP , %UCS2, %UNS, or %UNSH )”.
To this list I would add %SUBST(substring), at least.
I can think of no practical reason why the implementers did not simply allow MOVE into freeform. Perhaps it’s because I’m just an ignorant junior college grad, from when they didn’t even have CompSci courses in JC. Since I am not a computer science major, to me the implementation would be a snap; when the compiler sees “move field1 field2;” in freeform, do exactly the same thing you would if you saw MOVE FIELD1 FIELD2 in fixed format. (Copy the compiler code! What a revolutionary idea!)
I, for one, think the problem is ideological. MOVE (along with its cousins) is too powerful a code. Since high school grads (like me) know how to use it, it obviously is too difficult for CompSci graduates to understand; you must replace it with another opcode (EVAL) and one or more of at least 12 BIFs listed above. Makes it easier. Yeah, right. We must make it simple so the ignorant Java programmers can understand. Pardon me while I get ticked off by intellectual condescension. The compiler writers are evidently trying to pry us away from an operation they feel is somehow inferior. Never mind that it works reliably, precisely, and elegantly.
Never mind that you have to be very careful how you use the BIFs, since you might not end up with the exactly equivalent result. You wouldn’t have to bother if you didn’t change it in the first place. Multiply this by the millions upon millions of MOVEs and MOVELs that likely exist in existing code, and you begin to see the problem.
The code will almost certainly be longer and likely more complicated if you attempt to convert the code. You would think brevity would be prized, since it seems such a virtue when it goes the other way, when they come up with a BIF that seems to do the job more succinctly than its fixed-format equivalent. Apparently here, they are not shooting for brevity; and I find it hard to see how they enhance the clarity of the code by avoiding MOVE.
Frankly, if they are trying to promote the use of freeform, I think they are shooting themselves in the foot by not implementing MOVE. From what I have read on the RPG forums, the lack of MOVE support stands in the way of easy freeform conversion. The fixed-to-freeform converter cannot handle it, so a /END-FREE must precede it, dropping the code back into fixed-format. Many other opcodes can be handled more or less elegantly using BIFs; not using MOVE in freeform often ends up forcing the programmer to use some Rube Goldberg BIF to try to salvage the situation.

I can only wonder why they are taking an ideological stand on this subject. “Dumb” is the nicest word I can think of with reference to their decision.

It has been too long since my last post. What’s going on? Well, for one thing, I’ve done a couple of articles for work.com (a bit of shameless self-promotion here) , on “recovering data from a dead computer“  and another on “natural language processing” - text-to-speech and speech-to-text software.  I’m actually getting paid for my writing; and though I’m getting paid less than minimum wage (on an hourly basis) for doing it, it really is neat for your writing ability to be recognized.

But I haven’t really been all that busy writing those things. It’s kind of hard to explain. I think the problem is that I have convinced myself that everything I write must be a work of art, with detailed logic, clever phrases, and quotations. After the first flush of enthusiasm for the blog wore off, I found it not so easy to write through the brain fog that envelops your mind when you are tired at the end of the day. I have the energy to read my e-mail, surf my favorite web sites, but not enough to sustain several hours of determined composition.

But I should know better. Over and over again through the years I have read that the best way to write is to just sit down and do it. If you don’t feel like two hours of writing, do 15 minutes. That’s why this program I work with has a draft mode- what I write doesn’t immediately have to go to the Web. Just do it.

So I will try to do better. Just getting a new computer at work generates some enthusiasm. Things that took prohibitively long before now can be done so quickly. As a result, I have been enhancing and cleaning up the program and file cross-reference program I have written at work. I can track, in a nested fashion, what programs call what programs; and within a program I can click on a file name and get a file description or even display the file itself, scan the text for strings, and other neat stuff.  When it took well over an hour to generate the files necessary for the program, and now the files can be generated in under two minutes- that just gives you more of a feeling of power.

I was receiving the Web statistics on my various posts, and I found it very interesting that the articles that seemed to generate the most interest involved, in some fashion, freeform RPG. Even though I myself am not a big fan of it, it may be interesting to pursue that topic further in future posts, perhaps in a less dismissive way. I still believe in the validity of my arguments, but it may be worthwhile to analyze it to see why people are intrigued by it.

#1. And the best reason to code in free-format syntax is: We can finally see the structure of our code as we work with it!

Just a few more words on that last point. Free-format is just that - free. A programmer can choose to start a statement in any column after column 7 and continue through to column 80. So nested logic can now be indented, allowing us to craft code that conveys an immediate and intuitive sense of the order and conditions of execution. Nested fixed-format code can be difficult to work with, and if it’s deeply nested it can be an outright nightmare. This problem is removed in free-format RPG. Properly indented nested control structures tell the story at a glance. It simply takes less mental energy to understand the intent of well-written free-format code.”

Before we go too deeply, note the use of “weasel” words. Weasel words are words that you can use to show, if someone questions you on the validity of a claim, that you qualified it so that it didn’t say what he thought it said. (I learned the expression in a book on advertising.) Note- nested fixed-format CAN BE (not IS) difficult to work with. PROPERLY INDENTED (not ALL) control structures tell the story at a glance. And the reference to WELL-WRITTEN free-format code. This allows you to say that if the nested code is obscure, it was not properly indented or well-written. Somewhat different than the common unqualified claims that free-format code IS easier to understand.

We are not under the illusion that what follows will convince people to use fixed format instead of free-format RPG. What we do hope is that a free-format advocate will look at the whole situation with a more open-minded attitude than he does now, that it is not an open-and-shut case that free-format is easier or more usable.

But to proceed:

1. Note that word “intuitive” used again. As with our previous posts, we ask: Intuitive for whom? And the answer is the same- intuitive for the person who has been trained on block-structured code.

Brian Kelly, a noted ex-IBM Systems Engineer, author, and lecturer, gave these comments in a discussion of what he did and didn’t like about RPG IV:

“Hey, I liked RPG IV when it came out with the larger field sizes and the D: spec and the date operations. I am not as fond of the new RPG with its ILE connotations, difficult to understand procedure prototyping, and Java like built-in functions. I would have been happy without those. I liked being able to debug a customers code by looking on the right side of the RPG page looking for where a variable was changed or an indicator was turned on.” In other words, he liked fixed format, where he could expect to see result fields and indicators on the right side of the page. Free-format is not so easy or comfortable for those who are used to fixed-format code.

But perhaps you would expect that. These old stick-in-the-mud, died-in-the-wool coders are just too set in their ways, aren’t they? So let’s look at it a little more deeply. (more…)

Continuing with the article in which an RPG programmer describes why he loves freeform RPG so much, we find #3:
“’Eval’ is optional in free-format unless right-adjusting a character string or half-rounding a number. ‘Eval’ simply serves as a placeholder in fixed-format when writing extended factor2 assignment statements. It satisfies the compiler’s need for a non-blank value in the op-code column block (save for the exceptions noted above).”

Now, there’s a good reason!
EVAL is the logical equivalent of the LET keyword in BASIC.
That is, saying LET x=5 is the logical equivalent of EVAL X=5.
In BASIC, you can simply say, instead, X=5. Now, in freeform RPG, you can simply say, X=5; (and don’t forget that semicolon!).

BIG WHOOP. I’m sure not having to key in those four characters when you want to assign a variable a value will vastly improve your productivity. For me, actually keying in a program is the easiest part of programming. Even for a hunt-and-peck typist like me, keying in EVAL takes less than 2 seconds- one second once I’ve got that combination memorized by my fingers. If I don’t have to key 200 EVAL opcodes, that would save me about 1.5*200/60= about 5 minutes, not much in the larger scheme of things, since I would be taking anywhere from 5 to 20 seconds (for a particularly long line with multiple nested parentheses), maybe more, per line.

And then there’s #2:
“Longer field names are more easily accommodated, especially the typically more wordy subfield names in qualified data structures. Longer, more complex expressions can be written on each line. Once written they are more easily understood, since they’re likely not so spread across multiple continuation lines.”

I have to quote a line from one of my favorite books, “The Psychology of Computer Programming”, by Gerald M. Weinberg. Some of the language references are dated, since it was published in 1971, but its essential points remain valid. In the chapter “How Can We Study Programming”, he presented this beautiful line of PL/I code to consider what programming insights could be done via introspection:

ANGLES(I)=2*ATAND(SQRT((S-A(IND(I,1)))*(S-A(IND(I,2))))/(S*(S-A(IND(I,3))))));

Weinberg comments: “Now, a single case such as this contains many insights into problems in computing: the proper size of statements, the choice of data structures, the arrangement of different parts of a program, the use of parentheses rather than other techniques for decomposition, the design of compiler and execution-time diagnostics, and techniques for learning and teaching programming.”

Indeed. The very least it should teach us is that being able to create long, complex expressions is not necessarily a virtue. When you have to resort to dissecting three or four (or more) elongated lines of almost 75 characters each, you probably need to break up the statement, so you don’t lose the next programmer (or yourself, six months later) in your beautiful mathematical expression.

With the EVAL statement, very often (especially when piecing together a long string), I and others will often have to put together a long string of concatenated lines (with a + sign); we are forced to break them up, so will often line up the code, indenting and spacing it so the reader can see the field relationships readily. If we had nearly unlimited space, there would be no incentive to break up the line into manageable pieces. Being able to create long lines of parentheses four levels or more deep is not an advantage. We are not trying to derive complex mathematical formulas; we are attempting to write a legible program.

If you would say that you would keep the lines short, then the above “advantage” disappears.