Subject: bug#2379: [PATCH?] lisp.el: beginning-of-defun

From: "Aaron S. Hawley" <[email-masked]>
Date: Wed, 18 Feb 2009 21:37:39 -0500

There's some strange programming style in `beginning-of-defun-raw' for
Emacs 22.2, perhaps this is what was meant by the use of this `progn'
syntax?

--- lisp.el	18 Feb 2009 20:56:29 -0500	1.79.2.3
+++ lisp.el	18 Feb 2009 21:07:49 -0500	
@@ -234,7 +234,7 @@
 					 "\\(?:" defun-prompt-regexp "\\)\\s(")
 			       "^\\s(")
 			     nil 'move arg)
-	 (progn (goto-char (1- (match-end 0)))) t))
+	 (progn (goto-char (1- (match-end 0))) t)))

    ;; If open-paren-in-column-0-is-defun-start and defun-prompt-regexp
    ;; are both nil, column 0 has no significance - so scan forward

If not, then this is what it probably should be:

--- lisp.el	18 Feb 2009 20:56:29 -0500	1.79.2.3
+++ lisp.el	18 Feb 2009 21:10:21 -0500	
@@ -234,7 +234,7 @@
 					 "\\(?:" defun-prompt-regexp "\\)\\s(")
 			       "^\\s(")
 			     nil 'move arg)
-	 (progn (goto-char (1- (match-end 0)))) t))
+	 (goto-char (1- (match-end 0)))))

    ;; If open-paren-in-column-0-is-defun-start and defun-prompt-regexp
    ;; are both nil, column 0 has no significance - so scan forward

Then, once that is figured out, why doesn't `beginning-of-defun'
manage zero arguments like many of the movement commands do?  Running
C-0 C-M-a seems to run `beginning-of-line' regardless.  That's an easy
fix with this patch:

--- lisp.el	18 Feb 2009 20:56:29 -0500	1.79.2.3
+++ lisp.el	18 Feb 2009 21:25:05 -0500	
@@ -204,7 +204,7 @@
       (and transient-mark-mode mark-active)
       (push-mark))
   (and (beginning-of-defun-raw arg)
-       (progn (beginning-of-line) t)))
+       (progn (if (and (integerp arg) (/= arg 0)) (beginning-of-line)) t)))

 (defun beginning-of-defun-raw (&optional arg)
   "Move point to the character that starts a defun.

But then, `beginning-of-defun-raw' seems to run (forward-char -1).
That requires this patch.

--- lisp.el	18 Feb 2009 20:56:29 -0500	1.79.2.3
+++ lisp.el	18 Feb 2009 21:28:22 -0500	
@@ -234,7 +234,7 @@
 					 "\\(?:" defun-prompt-regexp "\\)\\s(")
 			       "^\\s(")
 			     nil 'move arg)
-	 (progn (goto-char (1- (match-end 0)))) t))
+	 (progn (or (zerop arg) (goto-char (1- (match-end 0))))) t))

    ;; If open-paren-in-column-0-is-defun-start and defun-prompt-regexp
    ;; are both nil, column 0 has no significance - so scan forward

That's my best look at the situation.

Support for a zero argument in these functions is important for
situations where you want to be programmatic with
`beginning-of-defun',   Can this be fixed?

Thanks,
/a