Re: [PATCH] Lookup functions, take two

[Bastien <bzg@altern.org>]

Achim Gratz <Stromeko@nexgo.de> writes:

> You could ask on the Emacs devel list if that'd be OK.

I suggest using this code:

(defun org-lookup (val s-list r-list lastp &optional predicate)
  "Look for VAL in S-LIST and return the corresponding element in R-LIST.
If LASTP, ignore all matching VAL in SEARCH-LIST except the last one.
If PREDICATE is not nil, use this instead of `equal' to match VAL."
  (let ((p (or predicate 'equal)) (c 0) r)
    (nth (dolist (i search-list r) (setq c (1+ c))
		 (if (and (funcall p val i) (or lastp (not r)))
		     (setq r (1- c))))
	 return-list)))

(defun org-lookup-first (val s-list r-list &optional predicate)
  "Look for VAL in S-LIST and return the corresponding element in R-LIST.
If PREDICATE is not nil, use this instead of `equal' to match VAL."
  (org-lookup val s-list r-list nil predicate))

(defun org-lookup-last (val s-list r-list &optional predicate)
  "Look for VAL in S-LIST and return the corresponding element in R-LIST.
If PREDICATE is not nil, use this instead of `equal' to match VAL."
  (org-lookup val s-list r-list t predicate))

;; (org-lookup-first 2 '(1 2 3 2) '(A B C D E)) => B
;; (org-lookup-last 2 '(1 2 3 2) '(A B C D E))  => D

No `cl-position' anymore.

Less dense and elegant, of course, but more explicit.  Users will be
able to check the docstring of org-lookup-first/last, which I think is
good for functions that we advertize in the manual.

Jarmo, would you be okay if I commit this?

Then you can commit a <20 lines patch for the documentation :)  
Or you commit the code (19 lines!) and I commit the doc patch,
as you want!

Thanks,

-- 
 Bastien