Be an OpenVMS Application Developer
There are two main intents of this book...
- 1) Allow developers who know at least one of the covered languages on another platform to
quickly come up to speed on the OpenVMS platform
2) Assist current OpenVMS developers finding themselves having to work with a different
language on this platform.
Tips from the Book
- The /SPECIFICATION qualifier of the SORT command lets you identify a text file which
contains a plethora of power. You can define named fields, named keys, named test
conditions, inclusion criteria, omission criteria. In a batch job stream, you typically have a
lead program which creates the sort specification file (if you need to do record selection
that varies from run to run), execute the sort command, then write your follow-up program to
process the sorted data. This is a much more acceptable approach than writing one
massive executable which will run for hours without creating many entries in the log file.
Most developers I run into don’t know a lot about the sort specification file, so we are going
to cover it in the COBOL chapter.
- A reference is a “special” object. There is a reason we covered COBOL prior to covering C,
and references are it. You better have read that chapter. When we discussed the linkage
section in COBOL, we discussed how COBOL doesn’t really pass parameters unless it is
forced to pass them. The linkage section creates reference points back into the caller’s
working-storage section. These references allow your called module to use those values
just like they were your very own, but they aren’t. The reason most COBOL programmers
don’t even know there is a GIVING clause on the procedure division is because they know
the linkage section operates via references (unless you tell it not to). When you alter the
values of items passed by reference you are actually altering the values in the caller.
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