Re: Using CL to call RPG pgms -- RPG400-L

I have almost 1,5 year expirience in ILE RPG IV and now I realized that
almost evry RPG pgm I've made needed additional CL pgm that shold prepare
LIBL, clear output PFs and perform similar actions after pgm finises...

That's interesting. Why would you want to prepare the library list? Ican understand why you'd want to clear an output PF, but how often doesthat come up? And it's easy to do that in the RPG program.


I'm wondering would it be to complicated to perform all this within RPG
pgm (for example in separate module or subprocedure) with use of different
APIs (QCMDEXC) and explicit file OPENing. (inexaple. if I define file in f
spec with USROPN keyword would I get err. message if file is not in LIBL
on pgm start).

You'll get an error message when you use the OPEN op-code to open thefile. If your code is structured so that this OPEN is at the start ofyour program, then yes, you'll get an error at that time.

I suppose there exist some actions (as file override options for RPG pgm
that will be run) that must be defined in CL??

That's not true, overrides can be done anywhere, as long as it's beforethe files are opened.

However, I almost never need to do overrides. What do you use them for?The only time I use them is when I want to specify something likeDFRWRT(*NO) on a display file, or a DTAQ on a display file... I use anoverride so I don't have to remember to specify these things when thedisplay file is created.

But, again, this is unusual. If you're just pointing the file to adifferent name, library or member, use the EXTFILE and EXTMBR keywords.You can use a variable (if necessary) to specify the file or member, andyou can even make that variable a parameter if you need an outside programto control which file you use.

What is better practice? It's probably metter of programers style but it
would be nice to know how other programers do that.

Yeah, what's "better" is always a subjective question. Personally, I'vealways though it was an RPG program's responsibility to control how it'sfiles are opened, so I've always felt it made more sense to control it viaparameters than it did external overrides.


Not everyone feels that way, however.

Is there any situation when this start actions should be performed in CL?

Sometimes there are things that are much easier or more intuitive whenperformed in CL. For example, some of the RTV commands in CL providefunctions that are otherwise only available via APIs -- so they're mucheasier to code in CL.

I have to admit, I don't often need to use these things, but when I do, Igeneral do them in CL.