Re: How to change overlay arrow position silently?

[Juri Linkov]

>> (mapc
>>  (lambda (n)
>>    (goto-line n)
>>    (set-marker overlay-arrow-position
>>                (point-marker)))
>>  '(1 2 3 4 5))
>> =>
>> Mark set [5 times]
>
> It is `goto-line' that prints this.

Its docstring says it can be used non-interactively:

  When called from Lisp code, the optional argument BUFFER
  ==========================
  specifies a buffer to switch to.

This means it is not a purely interactive command unlike
e.g. `query-replace' etc.

Therefore we need to distinguish interactive and non-interactive calls.
I remember Richard insisted on adding a new argument instead of relying
on `called-interactively-p'.  So perhaps the right fix is following.

Another option would be using a prefix argument C-u like
`M-<' (`beginning-of-buffer') and `M->' (`end-of-buffer') do
to not set mark at previous position.  But `goto-line'
already uses the C-u argument to move point in the most recently
selected other buffer.

Index: lisp/simple.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/simple.el,v
retrieving revision 1.1001
diff -u -r1.1001 simple.el
--- lisp/simple.el      31 Jul 2009 02:14:46 -0000      1.1001
+++ lisp/simple.el      3 Aug 2009 00:12:29 -0000
@@ -843,7 +843,7 @@
 
 ;; Counting lines, one way or another.
 
-(defun goto-line (line &optional buffer)
+(defun goto-line (line &optional buffer interactivep)
   "Goto LINE, counting from line 1 at beginning of buffer.
 Normally, move point in the current buffer, and leave mark at the
 previous position.  With just \\[universal-argument] as argument,
@@ -855,7 +855,7 @@
 LINE."
   (interactive
    (if (and current-prefix-arg (not (consp current-prefix-arg)))
-       (list (prefix-numeric-value current-prefix-arg))
+       (list (prefix-numeric-value current-prefix-arg t))
      ;; Look for a default, a number in the buffer at point.
      (let* ((default
              (save-excursion
@@ -881,18 +881,18 @@
                                   nil nil t
                                   'minibuffer-history
                                   default)
-            buffer))))
+            buffer t))))
   ;; Switch to the desired buffer, one way or another.
   (if buffer
       (let ((window (get-buffer-window buffer)))
        (if window (select-window window)
          (switch-to-buffer-other-window buffer))))
   ;; Leave mark at previous position
-  (or (region-active-p) (push-mark))
+  (or (not interactivep) (region-active-p) (push-mark))
   ;; Move to the specified line number in that buffer.
   (save-restriction
     (widen)
-    (goto-char 1)
+    (goto-char (point-min))
     (if (eq selective-display t)
        (re-search-forward "[\n\C-m]" nil 'end (1- line))
       (forward-line (1- line)))))

-- 
Juri Linkov
http://www.jurta.org/emacs/