Re: Bug: R src blocks fail to produce link to graphics file [9.3 org-plus-contrib-20200127]

[Jack Kamm <jackkamm@gmail.com>]

> Is the rationale explained anywhere? After a bit of poking around, it looks like using the `:file` flag without a `file` argument to results doesn't do anything (no file is created), nor does the reverse. That is, unless you use both the `file` argument and the `:file` option, nothing happens. Is there a situation where you can use `:file` to do something that doesn't require a `file` argument to `:results`?

The specific commit where it happened was
26ed66b23335eb389f1f2859e409f46f66279e15, which says:

"Deducing the results from some other arguments is not obvious.
Moreover, it prevents users from setting, e.g., :file-ext, in a node
property, as every block would then create a file."

The commit also links to this thread:
http://lists.gnu.org/r/emacs-orgmode/2018-05/msg00469.html

I wasn't involved in that discussion, but I think the idea is that you
could create a subtree with many named source blocks each creating a PNG
file, set the :file-ext parameter at the subtree level, and have the
file names auto-created from the source block names.

> The documentation for ob-R is now incorrect:
>
>   https://orgmode.org/worg/org-contrib/babel/languages/ob-doc-R.html

Yes, also that page could use some other updates, e.g. there are some
dead links in there.