[Info-vax] completion status from LIB$SPAWN

[Paul Sture]

On Fri, 27 Apr 2012 18:54:32 -0400, David Froble wrote:

> Many years ago the argument for the constants and masks was, "DEC could
> change the value of something, and using the constants would mean your
> code would still work".  I've never seen any thing like this change, and
> I doubt I ever will, and if it happens it would be in my opinion a huge
> mistake.  Regardless, DEC encouraged the use of the constants...

IIRC somewhere around the transition from V3 to V4, error message numbers 
could and did change.  You were safe if you had used the constant names 
in programs, but existing DCL procedures with hard coded error numbers 
could break.

I definitely recall that during our migration to V4.0, I wrote some DCL 
which did something like this:

$ create xyzzy.dat
foo
$ sea xyzzy.dat cobblers
$ search_nomatches_status == $status
$ write sys$output search_nomatches_status

because I didn't trust the hard coded value that was in an existing 
procedure to remain the same in future releases.

Just to prove that point, running the above on V8.3:

%SEARCH-I-NOMATCHES, no strings matched
%X08D78053

and on V3.0

%SEARCH-I-NOMATCHES, no strings matched
%X08018053


-- 
Paul Sture