On Wed, 22 Jan 2020 at 16:22, David Boyes <[email protected]> wrote:
> I have an application that defines a data structure using the STRUCTURE > stage. I can define the structure and read the values of individual members > without difficulty – there’s a nice example of how to do it in the docs. > What I’m trying to do is reference a field of the structure for update with > new data. I understand that using PICK with the MEMBER operand lets me > filter the records down to the one I want, but nothing seems to let me > update the value. > There is no provision to change the structure once it is defined. If you change your mind on what the layout of the record is (possibly based on fields you've seen) you would use a different structure to map that new content. You can also make overlays if that makes more sense. You could have a selection stage split between different type of records and use the corresponding structure downstream. You can also map just the variant portion at some column in the record. But these definitions are all done before records flow through the SPEC or PICK stage. If the change of mind happens in a separate stage, you can define that new structure with the same name as local structure. The STRUCTURE LIST produces the layout as STRUCTURE understood it. I would imagine any non-trivial structure to be defined by some external layout transformed into STRUCTURE format. You could use the LIST output to verify your transformation process. Rob
