RE: Externally-Described Field used as array name.

[boldt@xxxxxxxxxx]

Njal wrote:
>What's the benefit of this (I/O to ext-desc struct) versus today's ability
>to define a "ds like(rcdfmt of file)"?
>
>I assumed he was after a function like the Windows API MapViewOfFile
>which would be more like System Service Tools (SST) sees all objects.

What are the benefits (other than just another ticky mark in the
announce letter)?  First, you can have one READ read into data
structure A and another read into DS B.  Some people might find
that useful, especially if they're using qualified data structures.
Secondly, since the DS matches the layout of the record format,
only one move of a block of bytes is needed, rather than moving
multiple fields, some of which may require data conversion.  And
so I/O may be a little faster.  OK, performance isn't really that
big an issue - the main thing is providing some additional
flexibility that some programmers have requested.

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com