Re: Structured links to headings with endless depth

[John Kitchin <jkitchin@andrew.cmu.edu>]

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I don't think this should be in org-mode, it is still too fragile in many
ways.

For example, what if you have a colon in your headlines, e.g. "A chapter
about Romans 15:13".  That will will mess up the suggested approach that
splits on ":".

What if you have duplicate headlines in a hierarchy, how would you specify
the nth one?

What if you have some convention to start at level 2 headlines? what would
you do then?

What about include files?

What if you skip a level for some reason? What should the path look like
then?

If you can't put custom_ids in, the next best solution for a static file
might be to just jump to line numbers, and use a path-like link
description. That will allow you to jump to a precise line with a link that
looks like the path to that line.

[[file:some/file.org::43][1:2:3]]

Here is a function that will copy a link to the kill ring from the current
point so it is easy to paste somewhere. That link will fold so it looks
like 1:2:3 visually.

#+BEGIN_SRC emacs-lisp
(defun copy-link-with-path ()
  (interactive)
  (let ((line)
(fname (buffer-file-name))
(path-components '()))
    (save-excursion
      (org-back-to-heading)
      (setq line (line-number-at-pos))
      (push (nth 4 (org-heading-components)) path-components)

      (while (org-up-heading-safe)
(when (looking-at "*")
  (push (nth 4 (org-heading-components)) path-components)))
      (kill-new (format "[[file:%s::%s][%s]]"
fname
line
(s-join ":" path-components))))))
#+END_SRC





John

-----------------------------------
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu


On Wed, Mar 14, 2018 at 3:10 AM, ST <smntov@gmail.com> wrote:

> John, thank you for this solution!
>
> I posted this question also here:
>
> https://emacs.stackexchange.com/q/39384/18760
>
> So if you wish, you may add your solution also there.
>
> Somebody there, posted also a possible solution however the syntax is
> pretty heavy:
>
> [[org-heading:/path/to/file.org::*1:2:1]]
>
> There is a workaround using links abbreviations, but still it is a
> workaround...
>
> I think this kind of linking is useful for many general cases. Christian
> has expressed concerns that such links are easily breakable which is
> true but only for documents that are in draft phase (or those which are
> supposed to be restructured on regular basis - like ToDo lists). However
> documents that has been published, like books or scientific papers, and
> will no longer change - will benefit greatly from such linking option.
> Imagine you have a scientific paper in your archive that you have
> already published and removed write access from it in order not to
> change it accidentally. You do want to reference certain
> chapter:section:subsection from it in your new paper, which you are
> currently writing, but creating a target <<chapter:section:subsection>>
> in the old paper is no longer an option...
>
> So may I ask as a feature request, to please add, following link type as
> standard to the org-mode:
>
> [[path/to/file.org::chapter:section:subsection:etc:optional target]]
>
> - chapter/section/subsection could be also just numbers
> - optional target target might be <<optional target target>>
> - there is no need to add '*' (like
> [[path/to/file.org::*chapter:section]] to the link, as ':' after '::'
> imply that headings are referred.
>
> Thank you!
>
> On Tue, 2018-03-13 at 20:49 -0700, John Kitchin wrote:
> > This is a tricky problem to generally solve. I think this does it
> > approximately well enough. It is lightly tested and works by exactly
> > matching headlines at subsequent levels. It will be problematic if you
> > have headlines with : in them, and it assumes there is a level 1
> > headline to start in.
> >
> >
> > #+BEGIN_SRC emacs-lisp
> > (defun xpath-follow (path)
> >   (let* ((fields (split-string path "::"))
> > (fname (car fields))
> > (paths (split-string (cadr fields) ":"))
> > (level 0)
> > (current-point (point))
> > cp hls n found)
> >     (org-mark-ring-push)
> >     (find-file fname)
> >     (save-restriction
> >       (while paths
> > (setq cp (pop paths))
> > (incf level)
> > (setq hls (org-element-map (org-element-parse-buffer) 'headline
> >     (lambda (hl)
> >       (when (eq level (org-element-property :level hl))
> > hl))))
> > (setq n (-find-index (lambda (hl)
> >        (string= cp (org-no-properties
> >     (org-element-property :raw-value hl))))
> >      hls))
> > (if (not n)
> >     (progn
> >       (goto-char current-point)
> >       (user-error "%s not found" cp))
> >   (goto-char (org-element-property :begin (nth n hls)))
> >   (org-narrow-to-subtree))))))
> >
> >
> > (org-link-set-parameters
> >  "xpath"
> >  :follow 'xpath-follow)
> > #+END_SRC
> >
> >
> >
> > John
> >
> > -----------------------------------
> > Professor John Kitchin
> > Doherty Hall A207F
> > Department of Chemical Engineering
> > Carnegie Mellon University
> > Pittsburgh, PA 15213
> > 412-268-7803
> > @johnkitchin
> > http://kitchingroup.cheme.cmu.edu
> >
> >
> >
> > On Mon, Mar 12, 2018 at 8:08 AM, ST <smntov@gmail.com> wrote:
> >         Hello,
> >
> >         Ss Christian has pointed out - introduce a separate CUSTOM_ID
> >         for text
> >         with fixed structure and rather short verses is too heavy.
> >
> >         I do need to write a custom link type, if this use case is not
> >         of common
> >         interest for the orgmode community.
> >
> >         Thank you,
> >
> >
> >         On Mon, 2018-03-12 at 15:10 +0100, Nicolas Goaziou wrote:
> >         > Hello,
> >         >
> >         > ST <smntov@gmail.com> writes:
> >         >
> >         > > I'm not that experienced in writing in lisp. Is it
> >         difficult to create
> >         > > such custom link type? What is the closest link type that
> >         you would
> >         > > recommend to take as starting point (link on code, if
> >         possible)?
> >         >
> >         > I'm not answering your question, but I suggest to use a
> >         CUSTOM_ID
> >         > instead. This is readily available.
> >         >
> >         > Regards,
> >         >
> >
> >
> >
> >
> >
>
>

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