Re: Data Structure redefinition

[Jim Langston <jimlangston@xxxxxxxxxxxxxxxx>]

Hmm.. I'm not sure if I agree with that statement.  What about this?

D BB          S        10A

D MyStru     DS
D  AA                  10A
D  BB                  10A
D  CC                  10A

Not positive this will compile, but you should get the idea.

This is more commonly seen in File structures, however, but think of
the case where you are using a variable in a Data Structure that also
exists in your file's DDS.

I would not guarantee that AA BB and CC were all stored contiguously with
each other.

Regards,

Jim Langston

bmorris@ca.ibm.com wrote:
> 
> >From: "M. Lazarus" <mlazarus@ttec.com>
> >Sent: Wednesday, November 01, 2000 3:00 PM
> >
> >    Is it possible to have a basing pointer on a DS subfield?  If not,
> why?
> >
> >    What I would effectively like to do is "redefine" DS fields in another
> > DS.  When dealing with outputting multiple "formats" of the same data, it
> > would be much easier to have multiple DS's with different layouts, but
> have
> > the subfields point to the same data.
> >
> >   This would eliminate multiple EVALs and would probably be a lot more
> > efficient, if it can be done.
> >
> >
> > Example:
> >
> > D    DS
> > D A            LIKE( AA )
> > D B            LIKE( BB )
> > D C            LIKE( CC )
> >
> > D    DS
> > D D            LIKE( AA ) BASED( D@ )
> > D         6    INZ( 'Space1' )
> > D E            LIKE( BB ) BASED( E@ )
> > D         6    INZ( 'Space2' )
> > D F            LIKE( CC ) BASED( F@ )
> >
> > C         EVAL D@ = %Addr( A )
> > C         EVAL E@ = %Addr( B )
> > C         EVAL F@ = %Addr( C )
> >
> 
> Mark, it's impossible (in RPG at least) to have a
> data structure whose subfields each have their storage
> somewhere else.  RPG data structures always have contiguous
> storage.
> 
> (I don't know of any language that would allow you to
> have two structures "ABCDEF" and "AB CD EF" where the
> ABs, CDs and EFs are actually the exact same storage.)
> 
> Barbara Morris
> 
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