Re: Updating file via datastructure

[Barbara Morris <bmorris@xxxxxxxxxx>]

Tony Carolla wrote:
> 
> I just started using data structures for file input, output and
> update, for speed reasons (you know I am a speed-freak ;) ), so I am
> curious.  Is there any advantage to using an external DS over one
> created with LIKEREC?  Also, should we figure that someday, the
> LIKEREC functionality in regards to using for input/output/update,
> will be phased out?
> 

There's no speed advantage either way to an external-DS over one created
with LIKEREC.  

With an externally-described data structure you can add more subfields,
which can be good if you want to define overlays.

I don't see LIKEREC being phased out.  LIKEREC has a mild advantage in
that there's a more obvious relationship between the record format and
the data structure, in the case of renames:

Ffile   IF   E          RENAME(rec : newRec)

D newDsR     DS          LIKEREC(newRec : *input)
D newDsE   E DS          EXTNAME(file : rec : *input)

     read  newRec newDsR;
     read  newRec newDsE;

I think the relationship between newDsR and newRec is more obvious than
that between newDsE and NewRec.