Re: Bug or not a bug? dot expansion in ob-shell

[Nick Dokos]

Hi Tim,

Tim Cross <address@hidden> writes:

> It seems to me that two separate issues have been mixed up and causing
> some confusion here. However, I think it is actually quite simple once
> we consider the issues separately.
>
> Issue 1: Defining the meaning of :result value and :result output
> Issue 2: Specifying what the default :result setting would be i.e.
> :result without a value/output specifier.
>
> Issue 1 seems the most straight-forward to me
> - output :: Whatever goes to stdout/stderr
> - value :: whatever would be returned by the execution of the code. This
> might be a return value (i.e. for some shell commands) or the value
> returned by a function (including shell functions i.e. bash function) or
> the last command executed etc. Essentially, anything returned (including
> nil) by the block. STDOUT/STDERR is never a return value (though some
> languages may send output to STDOUT/STDERR as well as returning it, in
> which case it would also be in :return value).
>
> Note that I don't agree that the only 'useful' result from shell blocks
> is output. You might have a complex shell script which uses source
> blocks to define shell functions
> that return values which you use via oweb expansion to include in other
> blocks etc.s
>
> With this definition, essentially :result value is essentially anything
> except whatever is sent to stdout/stderr.
>
> Issue 2 is a little more difficult. It is likely that a 'standard'
> default for :result that is the same for all languages is not
> possible/desired. The default will likely be a combination of what seems
> most natural for that language and what is most common usage for the
> majority of users. It could be that for some languages, the default for
> :result should be :result output and for others it should be :result
> value.
>
> Personally, I care less about issue 2 than issue 1. In the worst case, I
> will need to change my header arguments for some blocks and that would
> be easily automated. Far more critical is that :result value and :result
> output are clear, unambiguous and consistent. Any proposal to change
> these meanings because of different uses cases in languages is a bad
> idea. Instead, changing the 'default' would be preferable. Having shell
> source blocks return STDOUT/STDERR output for :result value is IMO a bad
> idea. Having shell blocks default to :result output when only specifying
> :result while having other languages, like python or clojure default to
> :result value seems far more preferable (provided differences are
> clearly documented of course).
> ...

Thanks for the (very clear) write-up. I can only nod my head
in violent agreement :-)

-- 
Nick

"There are only two hard problems in computer science: cache
invalidation, naming things, and off-by-one errors." -Martin Fowler