[ESS-bugs] ess-mode 5.3.6; inferior-R-input-sender modifies `current-buffer' when entering help(foo) at R prompt

[Lawrence Mitchell]

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inferior-R-input-sender can change the value of (current-buffer)
when the input is a help command.  Specifically,
ess-display-help-on-object sets the current buffer to be the
newly displayed *help* buffer.  This means that typing a help
command at the prompt gives an error

Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
  comint-send-input()
  inferior-ess-send-input()

This is because the comint-last-input-start and other markers
have no value in the *help* buffer.

The following patch fixes this problem by ensuring that
inferior-R-input-sender restores the correct buffer on exit.

Cheers,

Lawrence

diff -u ess-inf.el.bak ess-inf.el
--- ess-inf.el.bak	2007-09-13 14:45:46.000000000 +0100
+++ ess-inf.el	2008-03-04 11:51:18.000000000 +0000
@@ -1635,31 +1635,32 @@
   ;; REALLY only for debugging: this S_L_O_W_S D_O_W_N	 [here AND below]
   ;;(ess-write-to-dribble-buffer (format "(inf..-R-..): string='%s'; " string))
   ;; rmh: 2002-01-12 catch page() in R
-  (let ((help-string (or (string-match inferior-R-1-input-help string)
-			 (string-match inferior-R-2-input-help string)))
-	(page-string	 (string-match inferior-R-page	       string)))
-    (if (or help-string page-string)
-	(let* ((string2 (match-string 2 string))
-	       (string2-rt (concat string2 ".rt")))
-	  ;; (ess-write-to-dribble-buffer (format " new string='%s'\n" string2))
-	  (beginning-of-line)
-	  (if (looking-at inferior-ess-primary-prompt)
-	      (progn
-		(end-of-line)
-		(insert-before-markers string)) ;; emacs 21.0.105 and older
-	    (delete-backward-char 1))		;; emacs 21.0.106 and newer
-	  (if page-string
-	      (progn
-		(ess-command (concat string2 "\n")
-			     (get-buffer-create (concat string2 ".rt")))
-		(ess-eval-linewise "\n")
-		(switch-to-buffer-other-window string2-rt)
-		(R-transcript-mode))
-	    (ess-display-help-on-object
-	     (if (string= string2 "") "help" string2))
-	    (ess-eval-linewise "\n")))
-      ;; else:	normal command
-      (inferior-ess-input-sender proc string))))
+  (save-current-buffer
+    (let ((help-string (or (string-match inferior-R-1-input-help string)
+                           (string-match inferior-R-2-input-help string)))
+          (page-string	 (string-match inferior-R-page	       string)))
+      (if (or help-string page-string)
+          (let* ((string2 (match-string 2 string))
+                 (string2-rt (concat string2 ".rt")))
+            ;; (ess-write-to-dribble-buffer (format " new string='%s'\n" string2))
+            (beginning-of-line)
+            (if (looking-at inferior-ess-primary-prompt)
+                (progn
+                  (end-of-line)
+                  (insert-before-markers string)) ;; emacs 21.0.105 and older
+              (delete-backward-char 1)) ;; emacs 21.0.106 and newer
+            (if page-string
+                (progn
+                  (ess-command (concat string2 "\n")
+                               (get-buffer-create (concat string2 ".rt")))
+                  (ess-eval-linewise "\n")
+                  (switch-to-buffer-other-window string2-rt)
+                  (R-transcript-mode))
+              (ess-display-help-on-object
+               (if (string= string2 "") "help" string2))
+              (ess-eval-linewise "\n")))
+        ;; else:	normal command
+        (inferior-ess-input-sender proc string)))))
 
 
 (defun inferior-ess-send-input ()

Diff finished.  Tue Mar  4 12:08:22 2008

Emacs  : GNU Emacs 23.0.60.3 (i686-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2008-02-26 on lamacq.ph.ed.ac.uk
Package: ess-mode 5.3.6

current state:
==============
(setq
 ess-language "S"
 ess-dialect "R"
 ess-ask-for-ess-directory t
 ess-ask-about-transfile nil
 ess-directory nil
 ess-keep-dump-files "always"
 ess-source-directory "/tmp/"
 )
-- 
Lawrence Mitchell <wence at gmx.li>