SOLVED, RE: Opening externally-described files as program-described (again)

["James H H Lampert" <jamesl@xxxxxxxxxxx>]

Joep Beckeringh had the key (no pun intended):
> My experience with program-described files is that the key length in the
F-spec is only used at compile time. At run time whatever
> you use as key is 'thrown at the database manager', which handles it. So
you might use a data structure as key and at run time use
> the appropriate layout.

So as an experiment, I simply set up a data structure for the key:

 DENTKEY                   5     22A
 DCONKEY                   3     20
 DENCTKEY                  1     18A
 DREFKEY                  14     18S 0
 DENTID                    5     13S 0
 DCONID                    3     13S 0
 DENCTID                   1     13S 0

padding the "9+5" and "11+5" keys on the end, and wrote a simple program
around it, with program-described F-specs for files of all 3 flavors (but
treating all 3 as having the "13+5" key layout), taking parameters for the
file number and the two keyfields, building up the key, trying to chain to
the files, and DSPLYing the first 50 characters of whatever it finds.

Once I got the thing to compile (i.e., the aforementioned padding on the
"9+5" and "11+5"), and got rid of a DD error (by putting a CMD front-end
on it), it worked perfectly.

Which points out one crucial rule so many of us forget: just because
something looks too simple to work doesn't mean it won't.

--
JHHL