Re: Suggestion to change the behavior of M-r

[Deniz Dogan <deniz.a.m.dogan@gmail.com>]

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2009/4/19 Deniz Dogan <deniz.a.m.dogan@gmail.com>:
> Hi
>
> I recently found out about the M-r keybinding, which by default is
> bound to move-to-window-line. Already knowing about the C-l keybinding
> (recenter-top-bottom) I was a bit thrown off when I found out that M-r
> doesn't behave in the same way. This got me thinking that the behavior
> of M-r should be changed to behave somewhat like C-l. So I basically
> stole the code for recenter-top-bottom and modified it to work with
> move-to-window-line instead.
>
> This is the result:
>
> (defvar move-to-window-line-last-op nil
>  "Indicates the last move-to-window-line operation performed.
> Possible values: `top', `middle', `bottom'.")
>
> (defun move-to-window-line-top-bottom (&optional arg)
>  (interactive "P")
>  (cond
>   (arg (move-to-window-line arg))                      ; Always respect ARG.
>   ((or (not (eq this-command last-command))            ; If this is
> not a repetition
>        (eq move-to-window-line-last-op 'bottom))       ; or if the last one
> put us at the bottom
>    (setq move-to-window-line-last-op 'middle)          ; then move it
> to the middle
>    (call-interactively 'move-to-window-line))
>   (t
>    (let ((this-scroll-margin
>           (min (max 0 scroll-margin)
>                (truncate (/ (window-body-height) 4.0)))))
>      (cond ((eq move-to-window-line-last-op 'middle)   ; If we're at the middle
>             (setq move-to-window-line-last-op 'top)    ; then move to the top
>             (move-to-window-line this-scroll-margin))
>            ((eq move-to-window-line-last-op 'top)      ; If we're at the top
>             (setq move-to-window-line-last-op 'bottom) ; then move to the bottom
>             (move-to-window-line (- -1 this-scroll-margin))))))))
>
> Please, do consider changing the behavior of M-r, of course not
> necessarily using the code above. If the code became a bit obfuscated
> on its way to the mailing list, I pasted it on lisp.org as well:
> http://paste.lisp.org/display/78841
>
> Thanks,
> Deniz Dogan
>

I'm guessing that no one is interested after all, but for convenience
I tried compiling a couple of patches for this change: one which adds
this functionality to lisp/window.el (and also binds it to M-r) and
one which updates etc/NEWS if it needs to be documented there.

-- 
Deniz Dogan

[-- Attachment #2: move-to-window-line-top-bottom.patch --]
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*** lisp/window.el	7 May 2009 09:21:31 -0000	1.180
--- lisp/window.el	12 Aug 2009 18:47:09 -0000
*************** Top and bottom destinations are actually
*** 1631,1636 ****
--- 1631,1669 ----
  	     (recenter (- -1 this-scroll-margin))))))))
  
  (define-key global-map [?\C-l] 'recenter-top-bottom)
+ 
+ (defvar move-to-window-line-last-op nil
+   "Indicates the last move-to-window-line operation performed.
+ Possible values: `top', `middle', `bottom'.")
+ 
+ (defun move-to-window-line-top-bottom (&optional arg)
+   "Position point relative to window.
+ 
+ With an argument, acts like `move-to-window-line'.
+ 
+ With no argument, positions point at center of window.
+ Successive calls positions point at the top, the bottom and again
+ at the center of the window."
+   (interactive "P")
+   (cond
+    (arg (move-to-window-line arg)) ; Always respect ARG.
+    ((or (not (eq this-command last-command))
+ 	(eq move-to-window-line-last-op 'bottom))
+     (setq move-to-window-line-last-op 'middle)
+     (call-interactively 'move-to-window-line))
+    (t
+     (let ((this-scroll-margin
+ 	   (min (max 0 scroll-margin)
+ 		(truncate (/ (window-body-height) 4.0)))))
+       (cond ((eq move-to-window-line-last-op 'middle)
+ 	     (setq move-to-window-line-last-op 'top)
+ 	     (move-to-window-line this-scroll-margin))
+ 	    ((eq move-to-window-line-last-op 'top)
+ 	     (setq move-to-window-line-last-op 'bottom)
+ 	     (move-to-window-line (- -1 this-scroll-margin))))))))
+ 
+ (define-key global-map [?\M-r] 'move-to-window-line-top-bottom)
+ 
  \f
  (defvar mouse-autoselect-window-timer nil
    "Timer used by delayed window autoselection.")

[-- Attachment #3: move-to-window-line-top-bottom-NEWS.patch --]
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*** etc/NEWS	8 Aug 2009 19:01:26 -0000	1.2059
--- etc/NEWS	12 Aug 2009 18:48:27 -0000
*************** variables to file-local variables in the
*** 93,98 ****
--- 93,101 ----
  +++
  ** The default value for `blink-matching-paren-distance' has been increased.
  
+ ---
+ ** M-r is now bound to `move-to-window-line-top-bottom' by default.
+ 
  \f
  * Changes in Specialized Modes and Packages in Emacs 23.2