RE: Knotty puzzle with chaining to files not known at compile tim e

Hi James,

I can think of some possibilities, none of which are overly nice:

1. Define the files that you are not sure of internally with the key info in
the F-spec and use USROPN as you have suggested. You may need to cater for
the buffer length mismatch on OPEN. As you seem to only need to determine
existence this should be enough.

2. Have a "template" for each of the possible files defining them externally
and compile the appropriate one (to get the appropriate rest of fields) then
call it to return the existence of the keys you are interested in. I am
puzzled that you also mention CHAIN. I thought that all you would need is
SETLL.

3. Use embedded SQL to do a SELECT INTO for each file and then determine
which one at run time. This would only need to mention the fields that you
know about.

4. Use the C native IO routines _Ropen, _RLocate & _Rclose.
 
Regards,

Kevin Wright 

-----Original Message-----
From: James H H Lampert [mailto:jamesl@xxxxxxxxxxx]
Sent: Tuesday, 4 July 2006 8:58 AM
To: rpg400-l@xxxxxxxxxxxx
Subject: Knotty puzzle with chaining to files not known at 
compile time


I've got a knotty little puzzle here:

I have a number of files. We know what their names are at 
compile time, but not necessarily which ones actually 
exist in any particular installation. We know that the 
files are keyed on two fields; the leading key is either 
9, 11, or 13 bytes zoned decimal, and the secondary key is 
always 5 bytes, but we have no way of knowing at compile 
time what the length of the leading key is.

All of this information can, however, be determined at 
runtime.

We also don't know much about the record structure at 
compile time, beyond the keys.

All we need to know is whether or not records exist for 
each of a series of specified composite key values.

Clearly, the fact that we don't know which of these files 
exist suggests treating them as USROPN, and not knowing 
the record structure suggests treating them as 
program-described. But any ideas on how I would chain to 
these files?

--
JHHL
-- 
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