Maybe I am missing the point here but it doesn't appear that it would do
what I have been doing for over 20 years with Business Basic. There I
enter a line saying SETERR 9200 at the beginning of the program and the
program automatically goes to that line when an error occurs anywhere in
the program. From there I can display a message saying what is wrong
and the operator can fix the problem and continue with the program or
abort the program.
That's true, and one of the trade-offs inherent to switching error
handling from a GOTO control structure to a scoped control structure
(such as bounded exception handling). The disadvantage is, as you've
explained, that each problem area must be contained within its own
error handling scope. The overwhelming advantage is that by catching
errors as close to their occurrence as possible, it becomes much
easier to identify just what went wrong, or pass the responsibility up
to the next thing that can. Exceptions were invented to help
programmers manage the complexity of handling errors.
Your example seems to require that I call a method anytime I run into a
problem. This would seem to require that each possible problem area be
surrounded by a while loop much like I have done in C.
It is possible to catch all (most) exceptions by placing your entire
program in a begin-rescue block, and the rescue procedure would
approximate what happens in the BASIC interrupt method. But if you do
that, the disadvantage to the BASIC approach might become clear as you
try to recover from the error. You'll have to know where to continue
execution, as well as make sure that the rest of the application is in
a similar state as it was before the error interrupted it.
For a good description of the topic, check this out:
http://stevemcconnell.com/ccgoto.htm
I hope this helps, and good luck with your project!
