Re: [babel, ess] How can I make S-RET to be multi-session friendly?

[Andrew Young <youngar17@gmail.com>]

Hello All,

Well, despite being relatively new to elisp, I've decided to take a
crack at one of your problems. I'm not too sure what is causing the
strange behaviour of the session property, but I have some thoughts on
getting that one function working.

Bear with me :-)

It seems that for me, the inferior ess process is not being properly
associated with the src edit buffer.  It is being set correctly by
org-babel-R-associate-session, and then being set a second time
incorrectly by org-babel-edit-prep:R.  Commenting out line 5 in
org-babel-edit-prep:R seems to fix this issue, although I'm honestly
not sure if or what it breaks.  Everything seems ok for me, but ymmv.

Heres the change:
#+begin_src emacs-lisp
  (defun org-babel-edit-prep:R (info)
    (let ((session (cdr (assoc :session (nth 2 info)))))
      (when (and session (string-match "^\\*\\(.+?\\)\\*$" session))
        (save-match-data (org-babel-R-initiate-session session nil))
        ;;(setq ess-local-process-name (match-string 1 session)))))
        )))
#+end_src

Is there any one having such issues, or who can weigh in on what
exactly is happening here?

Without making the above change, it is possible to manually attach an
ess process to the current src buffer by using the command:

C-c C-s (ess-switch-process)

You'll have to specify the process name, rather than the buffer name,
and the session must have already been started. From here all ESS
functions should work. For example, calling:

C-c C-z (ess-switch-to-end-of-ESS)

will open the session buffer.

I've implemented a variation of the function you mentioned, which uses
the inferior process discussed above.  It should do something at least
remotely like the function you were asking for, and will work with
babel sessions, as long as the ess process is associated
properly. I've made one change worth mentioning: the function now
prompts for a buffer name to set up on if no ess process is associated,
instead of only and always using *R*.

Try it out, and let me know what you think.  Of course feel free to
tweak & share!  This is my real first dive into lisp, so if anyone has
anything to share please do.

#+begin_src emacs-lisp
  (defun my-ess-eval ()
    (interactive)
    (update-ess-process-name-list)
    (if (not (ess-make-buffer-current))
        ;; Obtain the target ess session
        (let ((session
               (read-string "Use session: "
                            (let ((proc (get-process ess-current-process-name)))
                              (if (processp proc)
                                  (buffer-name (process-buffer proc)))))))
          ;; Obtain buffer matching session
          (if (not (get-buffer session))
              ;; If there is no buffer, create a new one
              (save-excursion
                (inferior-ess)
                (rename-buffer session)))
          (setq ess-local-process-name
                (process-name (get-buffer-process session)))))
    (ess-make-buffer-current)
    (if (and transient-mark-mode mark-active)
        (call-interactively 'ess-eval-region)
      (call-interactively 'ess-eval-line-and-step)))

    (add-hook 'ess-mode-hook
              '(lambda ()
                 (local-set-key [(shift return)] 'my-ess-eval)))

    (add-hook 'inferior-ess-mode-hook
              '(lambda ()
                 (local-set-key [C-up] 'comint-previous-input)
                 (local-set-key [C-down] 'comint-next-input)))

    (add-hook 'Rnw-mode-hook
              '(lambda ()
                 (local-set-key [(shift return)] 'my-ess-eval)))

  (require 'ess-site)

#+end_src

Sincerely,
Andrew Young