RE: Cancel & Condition Handlers (was: File update after abnormal programtermination)

>From: "Joe Pluta" <joepluta@PlutaBrothers.com>
>Date: Fri, 22 Feb 2002 12:17:24 -0600
>
>I remember running into this when I was learning condition handlers.  What
I
>would REALLY like is an option to retry an operation, but again it would
>have to be at the HLL level.  For example, a nice generic condition
handler
>would be to notice that you're missing a library in your library list (on
>either a program call or a database file open).  In that case, the
condition
>handler could add the library and then tell the HLL to retry the
operation.
>This would allow some very elegant error handling.  However, it would
>require some serious intrusion into the compiler - you'd have to be able
to
>"mark" HLL retry boundaries, and allow a completion method from the
>condition handler to restart execution at that mark.  It's not impossible,
>but it would definitely require some serious thought.

Joe, that sounds nice at first glance, but I think it would be fairly
complex to code, and the resulting code would be fairly mysterious.
Rather than have a condition handler that had to figure out if a
particular error was library-list related AND to figure out which
library was missing, how about this:

 /free
    for try = 1 to 2;
      monitor;
        open file;
      on-error;
        doCmd ('addlible whatever');
      endmon;
    endfor;

Maybe a bit more code, but it's straightforward, with the error
recovery close to the predicted error location.  If the library-list
setup was something job related rather than program related, the
recovery could be a call to some setupLibl program instead of the
addlible.

Barbara