For some reason every time you reply to a post it spins off a new thread
on my mail reader - gmail. It seems to be due to the fact that there is
no Re: prefix in the subject line.
On 12/08/2016 2:09 PM, Bill Woodger wrote:
I may have to reply initially with a thesis on "Not using FILE STATUS considered
harmful - and AT END even without NOT AT END is a worse pain" (I'll leave the
sub-tiles for later).
PROCESS-MY-FILE.
PERFORM UNTIL EXIT
READ MY-FILE
INTO MY-RECORD
AT END
EXIT PERFORM
NOT AT END
PERFORM PROCESS-MY-RECORD
END-READ
END-PERFORM.
What happens here if something "goes wrong with the file", something not quite
bad enough to kill the program, but something bad enough to get a non-zero FILE STATUS?
You get a Big Fat Loop.
AT END and it's brother are "ephemeral". Beyond the END-READ they do not exist.
The point about a "priming read" is not so much that you have to have two READs, it is
that you have two READs where there is a simple distinction (first vs not-first) which is highly
useful and which doesn't bog-up your other plain ordinary file-processing logic. Empty file - is
that OK? "Header processing"? Do you want to jam those into AT END/NOT AT END?
OK, you don't always need those - but does that drive you to having different constructs for
processing a file? With the priming-read, the processing of a record is only entered - when there
is a record. With the "read a record other than logically the last thing" there's always
code to skip out "just in case" the end-of-file happens (it pretty much always happens,
and potentially at least, always does happen).
Unfortunately I don't have time to read more now. I have to say that the religious jargon is
entirely unknown to me, but I think if I just treat it as a "progression", I'll be on the
right track? I'm not going to look up religious words on the internet for any nuance, just to be
able to understand this better - so if there is more meaning to their use than
"progression", please let me know :-)
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