Re: [PATCH v2] org-id: allow using parent's existing id in links to headlines

[Ihor Radchenko]

"Rick Lupton" <mail@ricklupton.name> writes:

> Please find attached updated patch which I think addresses all the points 
> discussed.  Let me know if you see any further changes needed.

Thanks!

I played around with the patch a bit and found a couple of rough edges:

1. When I try to open a link to non-existing search target, like
   <id:some-id::non-existing-target>, I get a query to create a new
   heading. If I reply "yes", a new heading is created. However, the
   heading is created at the end of the file and is always level 1,
   regardless of the "some-id" parent context.
   It would make more sense to create a new heading at the end of the
   id:some-id subtree.

2. Consider the following setting:
   (setq org-id-link-consider-parent-id t)
   (setq org-id-link-to-org-use-id 'create-if-interactive-and-no-custom-id)

   Then, create the following Org file

* Sub
* Parent here
** This is test
:PROPERTIES:
:ID:       fe40252e-0527-44c1-a990-12498991f167
:END:

*** Sub <point here>
:PROPERTIES:
:CUSTOM_ID:       subid
:END:

   When you M-x org-store-link, the stored link has ::*Sub instead of
   the expected ::#subid

3. Consider
   (setq org-id-link-consider-parent-id t)
   (setq org-id-link-to-org-use-id t)

   Then, create a new empty Org file
   M-x org-store-link with create a top-level properties drawer with ID
   and store the link. However, that link will not be a simple ID link,
   but also have ::PROPERTIES search string, which is not expected.

More inline comments below.

> +  #+vindex: org-id-link-consider-parent-id
> +  When ~org-id-link-consider-parent-id~ is ~t~, parent =ID= properties
> +  are considered.  This allows linking to specific targets, named
> +  blocks, or headlines (which may not have a globally unique =ID=
> +  themselves) within the context of a parent headline or file which
> +  does.

It would be nice to add an example, similar to what you did in the docstring.

> -(defun org-man-store-link ()
> +(defun org-man-store-link (&optional _interactive?)
>    "Store a link to a man page."
>    (when (memq major-mode '(Man-mode woman-mode))
>      ;; This is a man page, we do make this link.
> @@ -21312,13 +21324,15 @@ A review of =ol-man.el=:

Please, update the actual built-in :store functions in lisp/ol-*.el to
handle the new optional argument as well.

> +**** =org-link= store functions are passed an ~interactive?~ argument
> +
> +The ~:store:~ functions set for link types using
> +~org-link-set-parameters~ are now passed an ~interactive?~ argument,
> +indicating whether ~org-store-link~ was called interactively.

Please also explain that the existing functions are not broken.

> +*** ~org-id-store-link~ now adds search strings for precise link targets
> +
> +This new behaviour can be disabled generally by setting
> +~org-id-link-use-context~ to ~nil~, or when storing a specific link by
> +passing a prefix argument to ~org-store-link~.

universal argument.
There are several possible prefix arguments in `org-store-link', but
only C-u (universal argument) will give the described effect.
Also, won't the behavior be _toggled_ by the universal argument?

> +When using this feature, IDs should not include =::=, which is used in
> +links to indicate the start of the search string.  For backwards
> +compability, existing IDs including =::= will still be matched (but
> +cannot be used together with precise link targets).

Please add an org-lint checker that warns about such IDs and mention
this checker in the above.
Also, this paragraph belongs to "Breaking changes", not "new and changed
options".

> +*** New option ~org-id-link-consider-parent-id~ to allow =id:= links to 
> parent headlines
> +
> +For =id:= links, when this option is enabled, ~org-store-link~ will
> +look for ids from parent/ancestor headlines, if the current headline
> +does not have an id.
> +
> +Combined with the new ability for =id:= links to use search strings
> +for precise link targets (when =org-id-link-use-context= is =t=, which
> +is the default), this allows linking to specific headlines without
> +requiring every headline to have an id property, as long as the
> +headline is unique within a subtree that does have an id property.
> +
> +By giving files top-level id properties, links to headlines in the
> +file can be made more robust by using the file id instead of the file
> +path.

Please, provide an example here as well.

> +(defun org-link--try-link-store-functions (interactive?)
> +  "Try storing external links, prompting if more than one is possible.
> +
> +Each function returned by `org-store-link-functions' is called in
> +turn.  If multiple functions return non-nil, prompt for which
> +link should be stored.
> +
> +Return t when a link has been stored in `org-link-store-props'."

Please document INTERACTIVE? argument in the docstring.

> +  (let ((results-alist nil))
> +    (dolist (f (org-store-link-functions))
> +      (when (condition-case nil
> +                (funcall f interactive?)
> +              ;; XXX: The store function used (< Org 9.7) to accept no
> +              ;; arguments; provide backward compatibility support for
> +              ;; them.

Use FIXME, not XXX. (I have no idea why it is XXX in the existing code).

> +(defun org-link-precise-link-target (&optional relative-to)
> +  "Determine search string and description for storing a link.
> +
> +If a search string is found, return cons cell (SEARCH-STRING
> +. DESC).  Otherwise, return nil.
> +
> +If there is an active region, the contents is used (see
> +`org-link--context-from-region').

It is not clear from this sentence whether the contents is used for
SEARCH-STRING of DESC.

> +In org-mode buffers, if point is at a named element (e.g. a
> +source block), the name is used. If within a heading, the current
> +heading is used.

Please use double space between sentences.

> +Optional argument RELATIVE-TO specifies the buffer position where
> +the search will start from.  If the search target that would be
> +returned is already at this location, return nil to avoid
> +unnecessary search strings (for example, when using search
> +strings to find targets within org-id links)."

It is not clear what will happen if RELATIVE-TO is before/after point.

> -    (let (link cpltxt desc search custom-id agenda-link) ;; description
> +    (let ((org-link-context-for-files (org-xor org-link-context-for-files
> +                                               (equal arg '(4))))
> +          link cpltxt desc search custom-id agenda-link) ;; description
>        (cond
>         ;; Store a link using an external link type, if any function is
> -       ;; available. If more than one can generate a link from current
> -       ;; location, ask which one to use.
> +       ;; available.  If more than one can generate a link from
> +       ;; current location, ask which one to use.  Negate
> +       ;; `org-context-in-file-links' when given a single prefix arg.

The part of the comment about negation, should probably be moved near
the let binding of `org-link-context-for-files'.

> +For example, given this org file:
> +
> +* Parent
> +:PROPERTIES:
> +:ID: abc
> +:END:
> +** Child 1
> +** Child 2
> +
> +With `org-id-link-consider-parent-id' set to t, storing a link
> +with point at \"Child 1\" will produce a link \"id:abc\" to
> +\"Parent\".

This is actually confusing. May we only consider parent when
`org-id-link-use-context' is enabled?

> -(defun org-id-get (&optional epom create prefix)
> +(defun org-id-get (&optional epom create prefix inherit)
>    "Get the ID property of the entry at EPOM.
>  EPOM is an element, marker, or buffer position.
>  If EPOM is nil, refer to the entry at point.
>  If the entry does not have an ID, the function returns nil.
> +If INHERIT is non-nil, parents' IDs are also considered.
>  However, when CREATE is non-nil, create an ID if none is present already.
>  PREFIX will be passed through to `org-id-new'.
>  In any case, the ID of the entry is returned."

What about both CREATE and INHERIT being non-nil?

> +;;;###autoload
> +(defun org-id-store-link-maybe (&optional interactive?)
> +  "Store a link to the current entry using its ID if enabled.
> +
> +The value of `org-id-link-to-org-use-id' determines whether an ID
> +link should be stored, using `org-id-store-link'.
> +
> +Assume the function is called interactively if INTERACTIVE? is
> +non-nil."
> +  (interactive "p")

Do we really need to make it interactive?

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>