Emacs, R, Org-mode: how to enable automatic switch to ESS-mode within R code blocks?

Question

When using R code chunks in an .Rnw document, the emacs buffer automatically detects that the cursor is within a code chunk (i.e. within <<>> and @), and switches to ESS-mode -- this is very valuable because one can get ESS-based code-formatting within the code-chunk, and more-usefully, one can send code lines/regions to the inferior *R* process-buffer.

How do I get the same functionality in an org-mode file within R code blocks (i.e. between #+begin_src R and #+end_src) -- I'd like emacs to automatically recognize it's within an R code code block, and turn on ESS-mode so I can send snippets of code to the *R* process. I am aware that I can do Ctl-C ' and switch to a different ESS-mode buffer where I can edit the code and get all the other ESS-mode conveniences (including sending code to R). However I'd like to not have to do this, i.e. I want to be able to send code-snippets from the R code block in the same org-mode buffer.

Answer 1

AFAIK, this can not be done with the current implementation of Org-mode.

I'm not sure this is doable at all within Org-mode without some delving into elisp code. The main point of the C-c ' command in Org-mode is so that you have an additional buffer that has all the syntax highlighting that you want/need for your particular language.

There is probably a way to hack around this for R-specific code by writing some Org-mode hook that checks first to see if you are in an #+begin_src R ...#+end_src R block, and then checking for a code chunk. I suspect this would be messy and conflict with other Org-mode features. In addition, you would have to write another function to grab the current code block and pass it to Org-mode's R interpreter, along with all the options you added to the src block.