RE: Cleanup after program failure

Matthias Oertli wrote:

>I've been asked to code a call to program B from within program A.
-snip-
>My problem is this: If program B (or the CL) fails for whatever
>reason, program A regains control without the environment having been
>restored to what it should be which could mean disaster.
>
>How can I guard against this situation?

I would write the cleanup functions as a separate program/procedure; ideally
I'd include the "set up" and "remove" functions in one procedure and call it
with a parameter that tells it which to do.  That way all your environment
manipulation is done in one place.

Once you have that, have A call B and have B pass back a "success/fail"
flag.  Use whatever error trapping you need in B.  If B fails completely, A
can still check the return code.  If it is not set for "success"  have A
call the environment restore procedure.  If B completes, have it call the
environment restore procedure.

If you will be needing to do a lot of this, I would make a small change and
write an "environment save" procedure and an "environment restore"
procedure.  A does the save, B does the set, A does the restore.  That way A
is responsible for its own environment...

I hope these ideas get you started in a direction that will work for you!

Buck Calabro
Commsoft; Albany, NY
"Nothing is so firmly believed as
 that which we least know" -- Michel Montaigne
Visit the Midrange archives at http://www.midrange.com
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