RE: Midrange Knowledge test

[Jim Damato <jdamato@xxxxxxxxxxxxxxxxx>]

> Mark Lazarus:
>It seems odd to me that "everyone" is 
>ga-ga over (set-at-a-time) SQL, 
>which is basically mini program 
>with its own cycle, yet can't wrap their 
>brains around the RPG cycle!

Folks who were trained on relational database concepts from the start do not
view SQL statements as mini programs.  They do not conceive of SQL looping
through records one at a time.  They think of the statements as transactions
happening on a set of data.  ISAM trained RPG programmers would be the only
ones to conceive of SQL execution as a cycle.  They would translate the
set-based operation into an iterative process that they were more familiar
with.  I've seen RPG programmers explain JOINs as SETLL/READE loops.


>I don't understand how using 
>multiple platforms would influence your 
>decision whether to use the cycle or not.
>If you are using RPG in the first place, 
>multi-platform compatibility is not your
>first worry, since RPG is only truly 
>compatible to the IBM Midrange.

I guess I wasn't clear with what I was saying about readability.  I have
never been trained in COBOL or C, but I can read these programs and figure
out a lot of what they do.  I've thrown RPG program fixes at non-RPG
programmers and they've been able them out intuitively, to a point.  Two of
the principal unique characteristics of RPG are the cycle and indicators.
If you READE, immediately move the indicator to a meaningful field name, and
add a comment that says something like "invoice detail read successful", you
can make the indicator function clear to any intuitive programmer.  The
cycle has its own mysteries.  You have to know that the blocks of code are
triggered to execute for every read or every break at a certain key, and
that the READ loop is implicit (as well as the program's request for data).
A programmer from another platform will never pick that up intuitively.
It's a simple matter to write fully procedural program to visualize the READ
loop and establish the level break logic through an explicit initialization
routine and explicit comparisons of previous and current read data values.
And a developer with strong programming experience and minimal RPG
experience can read the code to figure out what the program does.

The cycle contains processing and logic, so that processing and logic is
concealed from view.  It's not hard to put it back in view, and it enhances
readability.  If you're not working in an exclusive RPG shop readability is
going to be much more important.

-Jim

James P. Damato
Manager - Technical Administration
Dollar General Corporation
<mailto:jdamato@xxxxxxxxxxxxxxxxx>