Re: bug: Error handling in source blocks.

[Tom Gillespie]

I will also chime in here to say that managing output streams and
errors for babel is a major new feature that I am interested in. The
issue, as Tim points out, is that there is a lot of complexity lurking
here due to the fact that certain languages have fundamentally
different capabilities and ways of handling or not handling errors,
and of running code (on arbitrary hosts) in the first place.

What works for one will almost certainly not work for another. Take
for example ob-lisp where there is already built in error handling in
emacs itself. Compare that with python where someone would likely need
to implement a special PYTHONBREAKPOINT entrypoint or something like
that, if it were possible at all.

I have had a draft of a document on what I called "babel
regularization" for well over a year now, but it is not in a state
that would be productive to share due to the sheer number of ob-langs
and systems affected and the need to be able to clearly catalog and
articulate the diversity of existing behaviors.

If you dig through old conversations on this list you will find a
discussion of the default behavior for ob-shell :returns values vs
output as the default, we were barely able to agree on which
principles should be followed to make the decision. In that case we
were lucky that there was already a way for users to set their desired
behavior in their init file or in a setup file or in the file itself.
How to handle errors will be much more complex, in part because it
will touch on what ob-lang implementations are able to overwrite
and/or must provide in order to actually function. At the moment there
are practically no constraints.

Lots of work to do here, so grateful for a report on the variability
in the behavior of the existing system.

Best!
Tom