Re: [Emacs-diffs] /srv/bzr/emacs/trunk r103444: * lisp/facemenu.el (list-colors-display): Use with-help-window (Bug#8048).

[martin rudalics <rudalics@gmx.at>]

 > > Unfortunately, we can't fill the buffer _before_ calling
 > > `with-help-window' because, as the comment above indicates,
 > > `list-colors-print' wants to know the width of the window _before_
 > > filling the buffer.

 > That's a common need, so with-help-window should display the buffer
 > before running the code.

Suppose we rewrote `with-output-to-temp-buffer' in Elisp then we would
probably come up with something like the following code:

      (let ((standard-output buffer))
        (setq value (progn ,@body)))

      (with-current-buffer buffer
        (set-buffer-modified-p nil)
        (goto-char (point-min)))

      (if (functionp temp-buffer-show-function)
	 (funcall temp-buffer-show-function buffer)
        (let ((window (display-buffer buffer)))
	 (when window
	   ;; Temporarily select window (and implicitly make the buffer
	   ;; current).
	   (with-selected-window window
	     (setq minibuffer-scroll-window window)
	     (set-window-start window (point-min))
	     (set-window-point window (point))
	     (run-hooks 'temp-buffer-show-hook)))))

      ;; Return last value of BODY.
      value))

If we now wanted to display the buffer _before_ evaluating BODY, we'd
have to splice in the evaluation into `temp-buffer-show-function'.  I
don't have the slightest idea how this could be reasonably done :-(

martin