Re: Handling Files in a Subproceedure

[Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx>]

Opening a file is a very expensive operation. (One of the most expensive 
ones that I use on a regular basis, in fact.)

So I guess the real question is:  How often do you expect your procedure 
to be called?  Are there programs (or can you envision a scenario) that 
need to call your procedure over and over in a loop?  If so, I'd say 
that opening and closing the file each time is a bad idea.  It's suicide 
to performance.

In my experience, the most common (and probably best) practice is to 
open the file once, and then just leave it open until the activation 
group or job ends.    Some people provide additional routines to allow 
the caller to explicitly re-open or re-close the files without having to 
end the activation group.

Are there circumstances where it makes sense to open the file on every 
call to the procedure?  Absolutely.  It really depends on what you're 
doing!   But, in 95% of the cases, you want to leave the file to improve 
the performance of subsequent calls.


Mike wrote:
> Maybe I worded it wrong. "Best Practice" maybe?
>
> It looks like others do the same thing open and close the file on every
> call. I didn't know if I could or should keep the file open while the main
> program is running. This is in a module by the way.