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

What???  Why would you have to program describe the file?  If you
externally describe the file and the data structure, when you retrieve a
record from the file, it'll automatically fill the external DS fields
also.  You don't need step 4 below.  In other words, why do you need the
ability to specify a DS name on an input operation for an externally
described file?

> ----------
> From:         Greg Thielen[SMTP:gregt@isda.com]
> Sent:         Friday, April 03, 1998 11:34 AM
> To:   MIDRANGE-L@midrange.com
> Subject:      RE: Ext-desc I/O using data structures (was:Field record
> relatio
> 
> Lorne,
> 
> Data structure IO for externally described files comes in handy if you
> want to 
> manipulate an entire record with one operation, as opposed to one
> operation for 
> each field (and what happens when you add more fields?).  You could
> externally 
> describe the data structire and program describe the file, but you
> lose the 
> ability to use keyed IO with key lists, partial keys, etc.  Consider
> that you 
> could:
> 
> 1) Define an externally described file.
> 2) Define an externally described data structure using the same file
> def.
> 3) Define a stand-alone field "like" the previous data structure.
> 4) Specify the DS name on an input instruction.
> 5) Copy the contents of the ext DS to the "like" field with one MOVE.
> 6) Copy the contents back with one MOVE.
> 
> 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.
> 
> 
> 
> On Thu, 2 Apr 1998 10:20:33 -0500, Lorne Sturgeoff wrote:
> 
> >I don't see the point of DS I/O for ext-desc files.  You can still
> have an 
> externally described DS for that file.  Normal input operations will
> move 
> database values into the subfields.  DS I/O if very useful for program
> described 
> files.
> >
> >-----Original Message-----
> >From:        Hans Boldt [SMTP:boldt@ca.ibm.com]
> >Sent:        Thursday, April 02, 1998 8:38 AM
> >To:  MIDRANGE-L@midrange.com
> >Subject:     Ext-desc I/O using data structures (was:Field record
> relatio
> >
> >Hi David!  Yes, you're right.  DS I/O is not allowed for ext-desc
> files in
> >RPG.
> >
> >Would you (or any other RPG programmer watching) like that limitation
> >removed in a future release?  IMHO, ext-desc data structures are very
> >useful and we should do more to support them.
> >
> >Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com
> >
> 
> 
> 
> 
> ------------------------------
> Greg Thielen
> Magellan Software, Inc.
> Home:   gregt@isda.com
> Office: gthielen@magsoft.com
>         http://www.magsoft.com
> 
> 
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