Enhancement patch: sum-rectangle and numerate-rectangle

[W Snyder]

I would like to propose the following additions to rect.el (diffs below
relative to Emacs 22.0.50).  I and my coworkers have found these very
useful, and I think they make a good small addition to the current set of
rectangle operations.

A argument could probably be made that there are other mathematical
operations that are useful.  I have experimented with several, but I've
found only summing is of general enough use to be worth inclusion in Emacs.
(Example use: with the output of a 'ls' listing, use sum-rectangle to sum
the sizes of all of the files.)

Thanks.

*** lisp/bindings.el    2005-08-30 16:36:34.000000000 -0400
--- lisp/bindings.el    2006-06-28 17:07:49.869246000 -0400
***************
*** 1012,1017 ****
--- 1012,1019 ----
  (define-key ctl-x-map "ry" 'yank-rectangle)
  (define-key ctl-x-map "ro" 'open-rectangle)
  (define-key ctl-x-map "rt" 'string-rectangle)
+ (define-key ctl-x-map "r=" 'sum-rectangle)
+ (define-key ctl-x-map "r#" 'numerate-rectangle)
  (define-key ctl-x-map "rw" 'window-configuration-to-register)
  (define-key ctl-x-map "rf" 'frame-configuration-to-register)
  
*** lisp/rect.el        2005-08-30 16:36:34.000000000 -0400
--- lisp/rect.el        2006-06-28 17:08:08.781739000 -0400
***************
*** 385,389 ****
--- 385,427 ----
  
  (provide 'rect)
  
+ ;;;###autoload
+ (defun numerate-rectangle (start end beginnum &optional increment)
+   "Insert sequential numbers on each line of the region-rectangle,
+ shifting text right.
+ The left edge of the rectangle specifies the column for insertion.
+ Called from a program, takes three args; START, END, BEGINNUM and
+ optional INCREMENT."
+   (interactive "r\nsStart number: ")
+   (setq increment (or increment 1))
+   (let ((num beginnum))
+     (apply-on-rectangle
+      '(lambda (startcol endcol &rest args)
+       (move-to-column-force startcol)
+       (let ((p (point)))
+         (move-to-column-force endcol)
+         (delete-region p (point)))
+       (insert num)
+       (setq num (int-to-string (+ increment (string-to-int num)))))
+      start end)))
+ 
+ ;;;###autoload
+ (defun sum-rectangle (start end)
+   "Sum the column of numbers with corners at point and mark.
+ Calling from program, supply two args START and END, buffer positions.
+ With a prefix argument, inserts the resulting sum at point."
+   (interactive "r")
+   (let ((sum 0.0))
+     (apply-on-rectangle
+      '(lambda (startcol endcol &rest args)
+       (setq sum (+ sum (string-to-number (buffer-substring
+                                           (progn (move-to-column startcol) 
(point))
+                                           (progn (move-to-column endcol) 
(point)))))))
+      start end)
+     (if current-prefix-arg
+       (insert (number-to-string sum))
+       (message (number-to-string sum)))
+     sum))
+ 
  ;;; arch-tag: 178847b3-1f50-4b03-83de-a6e911cc1d16
  ;;; rect.el ends here