> I am not even sure if all the babel backends support try-except. > Think about ob-gnuplot or, say, ob-latex.
Indeed many do not. Defining some standard "features" for org babel language implementations is something that is definitely of interest so that we can provide clear interfaces for things like stdio, error handling, return values, async, file output, remote execution, sessions, return value caching, module discovery/tangling, execution from file vs stdin, execution without a file system path, runtime environment specification, and much more. However, at the moment there is only a preliminary survey of a subset of these that was put together by Ian Martins. https://orgmode.org/worg/org-contrib/babel/languages/lang-compat.html > the two could be unified if we expand the functionality of the async filter While this might be possible, I would definitely hold off on this because the changes in semantics absolutely will break many users' blocks. We barely knew what the impact of changing the default return value for shell blocks would be. I absolutely look forward to the day when this can be done safely and with confidence, but I think we need a much stronger handle on babel interfaces in general before such a change could even be considered. At the moment each ob lang impl pretty much has to be considered to be completely unique, even if the text looks like bash for e.g. shell, comint, and screen. Users are known to rely on undocumented quirks of the ob lang impls that can differ wildly in their semantics. Best! Tom
