Re: READE EOF Handling/Repositioning

Hello John,

first, thanks for this elaborate explanation. Interesting insight!


Am 03.03.2020 um 23:02 schrieb John Yeung <gallium.arsenide@xxxxxxxxx>:

I still don't know why they couldn't be made to work with format. It's
very hard to imagine that there is any technical challenge whatsoever.
It's just a very mysterious hole in functionality.

Maybe they introduced *S/*E as companions to UNLOCK, which is to be used with the file and not a recfmt. My other guess, considering LFs: *S/*E are used for positioning the file pointer via file instead of a recfmt. Since there are certain restrictions for having different access paths in recfmts within *one* LF, *S/*E maybe have been thought to be less ambiguous than *L/H*. Fun starts with *L/*H when the AP is in DESCEND order. :-)

According to my theory, on a PF there should not be a difference in outcome between *S/*E and *L/H*. With LFs, well, "it depends".

I realize, very weak arguments. Sorry, my crystal ball is offline for maintenance. ;-)

(I exploit this file-and-not-recfmt-pointer for relative positioning when using load-paged SFLs. For READP, I read a recfmt with only the primary key field. For forward positioning/loading SFL with stock READ, I read only the fields which are actually needed in the SFL. Needed ≠ displayed, that is. LFs are a nice thing!)

:wq! PoC

PGP-Key: DDD3 4ABF 6413 38DE - https://www.pocnet.net/poc-key.asc