Re: splitting a window at point

[Tomas Nordin <tomasn@posteo.net>]

"James K. Lowden" <jklowden@speakeasy.net> writes:

> It seems like an obvious function: I'd like to split a window
> vertically, such that the top of the lower window is positioned where
> the cursor is.  If I'm on line 6, the top window will have 6 lines, and
> the bottom window gets the rest.  I (would) do this from time to time,
> to leave a function definition in the top window while in the lower
> window I operate on the code that uses it.  

Freely interpreting the goal and not refraining from jumping around with
point a bit, does the following do approximately what you want?

(defun tn-split-window-defun ()
  "Split window at point leaving beginning of defun visible in upper window."
  (interactive)
  (let ((start-pos (point))
        (start-line (line-number-at-pos))
        defun-lines)
    (beginning-of-defun)
    (setq defun-lines (1+ (- start-line (line-number-at-pos))))
    (split-window-below defun-lines)
    (window-resize nil (- defun-lines (window-body-height)))
    (recenter 0)
    (other-window 1)
    (goto-char start-pos)
    (recenter 0)))

--
Tomas