(string-rectangle (point-min) (point-max) "% ") behaves different in GNU and Xemacs

[Uwe Brauer]

Hi


The documentation of that string-rectangle  says
,----
| 
| Replace rectangle contents with STRING on each line.
| The length of STRING need not be the same as the rectangle width.
`----


But: when I mark a region and call string-rectangle
I obtain


% Again when I mark a region and call string-rectangle

But *not*


%

Therefore I tried out the  the following function in matlab mode.

(defun my-matlab-insert-simple-raw ()
  "Change and insert the content of the *Matlab Help* buffer.
  (Sometimes invoked with `matlab-shell-run-command'.)
`kill-empty-lines' put all results in one line, and `comment'
them out according to the `matlab' syntax."
  (interactive)
  (save-excursion
        (let   ((currentname  (current-buffer)))
          (switch-to-buffer "*MATLAB Help*")
          (toggle-read-only nil)
          (goto-char (point-min))
          (delete-empty-lines-region (point-min) (point-max))
          (goto-char (point-max))
          (delete-backward-char 1 nil)
          (goto-char (point-min))
          (while (re-search-forward  "=" nil t)
          (kill-line nil))
          (goto-char (point-min))
          (string-rectangle (point-min) (point-max) "% ")
          (switch-to-buffer currentname)
          (insert-buffer "*MATLAB Help*"))))

This works fine in Xemacs and inserts a line such as

% s=5

In the buffer of question.

In GNU emacs however string-rectangle behaves differently:
it  puts  the % at the beginning of the line but deletes the rest!

I debugged the function and the result of
(string-rectangle (point-min) (point-max) "% ")

In my example was:

Result: 3 (#o3, #x3, ?\C-c)


while in Xemacs it was a simple nil.

Meanwhile I found another solution which allows me to do what I want,
but I would like to understand why

(string-rectangle (point-min) (point-max) "% ")

behaves differently in GNU emacs from Xemacs, and how could I
nevertheless use this function without deletion.



Uwe Brauer