• Subject: Re: Eval Exception Error Trapping
  • From: "Scott Klement" <infosys@xxxxxxxxxxxx>
  • Date: 23 Jul 1999 14:08:37 -0500

Hans,

     I have to say that I really like the try/catch approach to error
handling.   (and, frankly, I *hate* the way error catching currently
works in RPG... its ugly, and often takes a lot of work to get it
to do what you want to do.)

I would, however, RPG-ize it a bit.   Make it work more like the
Select/When works now.  And make sure there is a way to determine
WHICH exception happened, and why...  (without having to resort
to various data structures such as the PSDS or INFDS)

maybe something like:
C                  TRY        ERRFLD
C         ..... insert one or more lines of code here...
C                  CATCH      ERRFLD = 'CPF2105'
C         ..... insert one or more lines of error handling code....
c                  CATCH      ERRFLD = 'CPF0001'
C         ..... insert one or more lines of error handling code....
C                  FINALLY
C         ....  more code again ...
C                  ENDTRY

Otherwise, I also like the way that C programs handle errors.
(check for a bad response, and then check errno to see what it
was, use strerror to get a text description, or use perror to
simply print that error)

As a third choice, I'd go for something like the CL MONMSG command...
Though this can get to be a bit awkward...  I'd prefer to have
something like try/catch where you can monitor multiple statements
of code all in one grouping...

Thats my 2 cents...

Scott Klement
Information Systems Manager
Klement's Sausage Co, Inc.


boldt@ca.ibm.com wrote:
>
> Jon wrote:
> >Hans - I like the try/catch type approach in some ways but it is
>  overkill in
> >many ways. Why not simply permit the coding of the "E" extender on
>  numeric
> >operations? That way I can trap at the statement level if I wish.
>
> On the other hand, the E extender, as currently designed, already
> has serious limitations.  For example, coding E on a WRITE will
> trap file exceptions, but not program exceptions.  But on other
> opcodes, it does trap program exceptions.
>
> Perhaps it is overkill, but when writing new apps, it's the only
> exception handling method you need to know about.  Today, you need
> to know about INFSR's, *PSSR's, error indicators, extender E, etc.
> MONITOR is one easy-to-understand technique that can replace all
> others.
>
> Cheers!  Hans
>
> Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com
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