Re: Post-process table without changing result for empty table(/list)

[Ihor Radchenko <yantar92@gmail.com>]

Jonas Bernoulli <jonas@bernoul.li> writes:

> It used to behave like that before 51a628bc5efc from 2009, which started
> turning all symbols, including nil, into strings, but without giving any
> reason why that should be done.
>
> It has worked like this for a long time now, so reverting that is
> probably not feasible in the short run.  However, I feel it would
> make sense to change now how nil/'() is treated.  Currently it is
> being treated as the symbol nil, but IMO it would make more sense
> to treat it as the empty list.  That could be achieved with
>
> diff --git a/lisp/ob-ref.el b/lisp/ob-ref.el
> index b79e47900..2b4a16aea 100644
> --- a/lisp/ob-ref.el
> +++ b/lisp/ob-ref.el
> @@ -199,7 +199,7 @@ (defun org-babel-ref-resolve (ref)
>                                 (org-babel-execute-src-block nil info params))))
>                      (error "Reference `%s' not found in this buffer" ref))))
>              (cond
> -             ((symbolp result) (format "%S" result))
> +             ((and result (symbolp result)) (format "%S" result))
>               ((and index (listp result))
>                (org-babel-ref-index-list index result))
>               (t result)))))))))

Looks reasonable.
Could you please prepare a patch and possibly also add a test that
covers your use-case to testing/lisp/test-ob.el?
See https://orgmode.org/worg/org-contribute.html

> In the long run you might want to consider not turning any symbols
> into strings, at least not when the "regular" block as well as the
> post-processing block both use elisp.

This may be tricky. Introducing any kind of special case will make the
code fragile. We should better make things as generic as possible.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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