RE: Ext-desc I/O using data structures (was:Field record relatio

At 08:34 AM 4/3/98 -0800, Greg Thielen wrote:
>This cannot be done now with externally described files, meaning, for example, 
> 
>that I could not use a composite key for the input operation.  This also 
>allows 
>me to not have to change the program if fields are added or removed from the 
>file--just recompile.  IMHO, this would be a very welcome feature.

Greg,

You can use composite keys with program described files. You just can't use a 
KLIST. The key is treated as if it were a single alphameric field. If you 
define a data structure containing the key subfields LIKE the fields in the 
input record, you can use the data structure name to CHAIN. You can also use 
partial keys that do not correspond to field boundaries (something that you 
cannot do with externally described files and KLISTs). Couple this with the 
ability to define the input record with an externally described data structure, 
and you still only need to recompile the program if you change the record. 
There are some caveats regarding LIKE and numeric storage format that 
occasionally cause problems at V3R1, but I think these have been corrected in 
later releases (I haven't had the opportunity to try it yet - going to V4R2 in 
a month or so).

Pete

Pete Hall
peteh@inwave.com 
http://www.inwave.com/~peteh/

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