Re: Error Handling
From: Robert Craig <rds at RapidEuphoria.com>
>
> What you are asking for now, is a full-blown
> exception handling mechanism. That might be
> worth doing, I'm not sure. I don't think it is the kind
> of panacea for all our programming sins that you and others
> are suggesting. In most cases when an error occurs
> in a program, that program is skating on very thin
> ice, and there is not much that you can do, or should do,
> other than shut it down and get as much diagnostic
> information as you can get. Soldiering on in the face
> subscript violations, uninitialized variables etc, would
> allow, in some cases, a program to complete
> a logical "transaction", saving user data from
> memory to disk, but in other cases it would allow
> an incorrect "transaction" to be completed.
> Undoing incorrect transactions is often more
> difficult than re-doing transactions that were never
> completed.
There's a certain elegance that could result from implementing
type() properly.
Since type() checks upon each and every assignment, that means
you only have to declare a handler once for each class of variable you
want to monitor, and your work is done, Wherever you declare an instance
of that variable type, the checking and recovery routines are automatically
in
place.
The alternative is to call a function with each and every assignment:
x = CheckValidHours(y) -- for an assignment.
x = CheckValidHours(get_number(work_hours)) -- for input
The problem with this is obvious; code bloat. It gets messy very quickly,
whereas, if type() operated as it should, this would be simple and
automatic.
x = get_number(work_hours)
Remember, once our programs are debugged, we are still at the mercy of
whoever is _using_ the program! Writing reams of code to check for every
conceivable
input error and subsequent math error that might result from various
unexpected combinations of that input is neither elegant or efficient.
There should be an easier way.
Regards,
Irv
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