Loitering with indent#

Wed, 08 Aug 2007 22:55:35 +0000

It's been one of those dependency^Wdistraction hell weeks. I'll spare you the details, because that way lies Rant, but by mid-afternoon today I found I'd upgraded Emacs to version 22 and was trying to write a new MUA by sticking bits of mel-base and ltk together, and getting really weird "stairstep" indentation for lists of keywords. This turned out to be nothing to do with stale fasls/elc files (first suspect) or with SLIME (second suspect) or with cl-indent (third suspect), but the underlying Emacs lisp indentation engine has had some changes to "try to align a constant-symbol under the last preceding constant symbol" which has had a completely undesirable knock-on effect on CL.

So, without further ado: my .emacs file now says

(require 'slime)
;; emacs 22 lisp indentation, if left to its own devices, indents
;; lists of keywords in a "stairstep" fashion like so
;; (list :foo :bar
;;       :baz :quux
;;            :bum :ki)
;;
;; this appears to be intentional (see comment "try to align a
;; constant-symbol under the last preceding constant symbol" in
;; lisp-mode.el) and perhaps it's even useful for elisp, but it makes
;; make-instance (for example) look bloody silly
(defun my-cl-indent-function (indent-point state)
  (let ((normal-indent (current-column)))
    (if (save-excursion
	  (goto-char indent-point)
	  (skip-chars-forward " \t")
	  (looking-at ":"))
	normal-indent
      (common-lisp-indent-function indent-point state))))
(slime-setup)
(add-hook 'lisp-mode-hook
	  (lambda () 
	    (setq lisp-indent-function 'my-cl-indent-function))
	  'append)

You need the hook (and you need it to run last) as SLIME also installs its own hook to make lisp-indent-fuction buffer-local and set it to common-lisp-indent-function