Let's talk about SUBFILE programming in RPG
If you have grown up through the world of AS400 a few decades ago, or through the wonderful ISERIES machines of the early 2000's then you *maybe* are using the current IBM i POWER SYSTEMS that replaced those old boxes.
If that's the case, in most places you are using subfiles to display information on those smelly old green screen terminals.
Writing a SUBFILE PROGRAM means knowing how to code them, ranging from simple full load, to expanding, to page at a time.
Each type of Subfile has different programming styles... so let's dive in and have a play with SUBFILES in RPG Programming.
Programming for IBM i - Everything You Wanted To Know About Subfiles But Were Afraid To Ask
Let's look at the basics of a subfile and how it works.
What are the SFL (Subfile) Indicators and how do they work?
SFL | SFLDSP | SFLDSPTCTL | SFLCLR
Introduction to a Simple RPG Subfile
So, I found an old RPGLE Subfile example on a website that is top of the search engine list. This means it's been visited and downloaded thousands of times. But does that mean it's anygood?
Don't waste time trying yourself - watch me do it for you :)
RPG Subfile DSPF - A Quick Look at the data description specifications (DDS)
RPG Subfile - Review the RPG program source code - Part 1 COPYBOOK
RPG Subfile - Review the RPG program source code - Part 2 RPG BODY
RPG Subfile - Making this dodgy program compile
RPG Subfile - Test the RPG program and see what it does
Now that we've walked through this RPGLE subfile example, and have a working version, we have to ask ourselves - IS THIS A GOOD EXAMPLE?
If YES - then what is good about it?
If NO - then what is bad? What do we hate? What do we tolerate? What can we improve?
If ***** (that is a swear word) then what kind of subfile example would I write?
*SPOILER ALERT* This subfile code example is NOT LITTEN APPROVED. Be prepared for some Bawdy Anglo-Saxon Expletives
About the teacher
IBM i Software Developer, Digital Dad, AS400 Anarchist, RPG Modernizer, Shameless Trekkie, Belligerent Nerd, Englishman Abroad and Passionate Eater of Cheese and Biscuits.
Nick Litten Dot Com is a mixture of blog posts that can be sometimes serious, frequently playful and probably down-right pointless all in the space of a day.
Enjoy your stay, feel free to comment and remember: If at first you don't succeed then skydiving probably isn't a hobby you should look into.