R-alpha: options [--no-*-file] AND --dont-stop-on-error-if-batch
Martin Maechler <email@example.com>
Fri, 22 Aug 1997 08:40:25 +0200
>>>>> "Kurt" == Kurt Hornik <firstname.lastname@example.org> writes:
>>>>> Thomas Lumley writes:
>> On Tue, 12 Aug 1997, Martin Maechler wrote:
MM> As Thomas Lumley has noted before, the behavior in 'batch mode'
MM> has changed; namely "Termination upon 'error'".
MM> I think this is THE good default behavior for "batch mode".
MM> However 1) for several purposes I'd very much want an option to
MM> change this default behavior.
>> Hear, hear!
MM> I think it'd be very neat then if options(error.stop = FALSE)
MM> actually translated all errors [stop(.)] to warnings [warning()].
>> I'm not convinced. Being able to make warnings fatal is a good
>> option, but being able to continue after errors may make no sense.
>> How do you continue after subscript out of bounds, or argument
>> missing with no default, or memory exhausted or ...
>> You may well need to jump back to the top level before it makes
>> sense to continue. On the other hand, once at the top level it is
>> certainly possible to proceed, and so there should be an option to
>> do it.
Kurt> There is an obvious trade-off between having a lot of flexibility
Kurt> and simple too many options :-)
I don't quite see (the ":-)").
The non-expert user just changes options like 'digits' and 'width'
and leaves the others alone.
Kurt> I am not sure about making warnings fatal. E.g., code for
Kurt> chisquare tests usually displays a warning if the approximation
Kurt> may be bad. That should never be fatal, though ...
The option exists in S.
It can be very useful for debugging purposes (and that't about it):
If you call a top level function / a for loop which in certain
circumstances produces warnings that look funny to you, and somehow it's
hard to detect when / why the warnings are produced.
Now you (temporarily) make warnings fatal, and also add something like
options(error = 'dump.frames') or an "on.exit(browser())".
You will now be able to quickly find and debug the circumstances under
which the warnings were produced.....
Kurt> Re termination upon error, couldn't there be situations with a
Kurt> huge simulation loop where one could still do something useful
Kurt> after e.g. running out of memory?
As I (and others) said, there are other situations where you just want to
run a source.R file through R and you don't care if somewhere an
unimportant variable is not defined, a graphics device is not open,....
Kurt> If I unterstand Martin correctly, the extra options() come into
Kurt> being only because command-line options are hard to port to
Kurt> point-and-click interfaces ...
This would be the main reason.
I think it's just 'neater' to have many things as part of R core,
instead of part of the OS-interface [to where command line options belong].
On the other hand, currently I (still) can't imagine myself moving off an
Unix based OS. Therefore, I'd be happy with a command line option which
turns off 'stop on error' in batch mode.
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