Re: org-store-link calls external link type store functions twice?

[Robert Adesam <robert@adesam.se>]

Hi,

I made a small example where I added an external link type, "counter"
that always works and updates a counter. It is quite crude but shows
my point:

(org-add-link-type "counter" 'ra/org-counter-open)
(add-hook 'org-store-link-functions 'ra/org-counter-store-link)

(defun ra/org-counter-store-link ()
  "Store a dummy counter link."
  (if (boundp 'counter)
      (setq counter (1+ counter))
    (setq counter 1))
  (let* ((link (concat "counter:" (number-to-string counter)))
         (desc (format "Calls to ra/org-counter-store-link: %d" counter)))
    (org-store-link-props
     :type "counter"
     :link link
     :description desc)))

(defun ra/org-counter-open (path)
  "Print and reset the counter."
  (message (format "Calls to ra/org-counter-store-link: %d. Resetting
counter." counter))
  (makunbound 'counter))

Running org-capture with the above external link type will result in
counter to be set to 2 before inserting the link in the *Capture*
buffer. I have also tried the example "A.3 Adding hyperlinks types" in
the manual -- same result when debugging org-man-store-link.

In the definition of org-store-link the interesting part is paste
below. I have marked the calls to external link types store function,
ie ra/org-counter-store-link above.

; Store a link using an external link type
((and (not (equal arg '(16)))
      (setq sfuns
	    (delq
	     nil (mapcar (lambda (f)
			   (let (fs) (if (funcall f) (push f fs)))) ;;; <-- first call to
ra/org-counter-store-link
			 org-store-link-functions))
	    sfunsn (mapcar (lambda (fu) (symbol-name (car fu))) sfuns))
      (or (and (cdr sfuns)
	       (funcall (intern
			 (completing-read
			  "Which function for creating the link? "
			  sfunsn t (car sfunsn)))))
	  (funcall (caar sfuns))) ;;; <-- second call to ra/org-counter-store-link
      (setq link (plist-get org-store-link-plist :link)
	    desc (or (plist-get org-store-link-plist
				:description) link))))

This "problem" only shows up in version 8 of org-mode, not version 7.
Please let me know if I can provide you with even more information.

Thanks for listening,
/robert

On Tue, May 14, 2013 at 10:41 AM, Bastien <bzg@gnu.org> wrote:
> Hi Robert,
>
> Robert Adesam <robert@adesam.se> writes:
>
>> I am not sure this is a bug but in version 8.x storing a link using
>> an external link type, org-store-link seems to call the external link
>> type's store function twice... I noticed this as I use an external
>> link type that asynchronous updates an external filedatabase and
>> started to get random file lock errors -- the org-store-link second
>> call to the external link type's store function sometimes came too
>> quickly after the first one. :-) Also, I do not have this problem in
>> version 7.x of orgmode.
>>
>> Instead of reverting back to a previous version of orgmode I started
>> to investigate -- attaching a patch that seems to help me anyway.
>> It's not that well tested and maybe, as I am not that familiar with
>> everything going on when storing a link using an external link type,
>> it will break other things...
>
> I re-read `org-store-link' and I don't see how the external function
> can be called twice... maybe you can give more details on what this
> external function looks like, when it is called (within a script or
> something), etc?
>
> Thanks!
>
> --
>  Bastien