Re: [PATCH v5] ol.el: add description format parameter to org-link-parameters

[Hugo Heagren <hugo@heagren.com>]

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> Can you also update the documentation for
> org-link-make-description-function?

I'm not sure what sort of documentation you have in mind? What should
I add?

> I have realized that even better option would be using map-do.

Agreed. Should be in the current version.

With regard to Max's comments:

> I am in doubts concerning "default-description" as the parameter
> name. I would consider either more specific "insert-description"

Having read your thoughts, I agree. I've converted the patch to use
"insert-description" where-ever relevant.

> Have I missed something or the whole macro may be simplified to just
> copy `org-link-parameters'?
>
>    `(let ((org-link-parameters (copy-tree org-link-parameters)))
>       (org-link-set-parameters ,type ,@parameters)
>       ,@body))

I had the same thought. I doesn't work though. `copy-tree' and
`copy-sequence' only make shallow copies of each element in a
sequence. `org-link-set-parameters' then uses side effects to alter
the `org-link-parameters', so these changes are propagated to the
copy. This means the values in the copy and the real
`org-link-parameters' are always the same, and so we can't use the
copy to store the original values (which is what we need it to do).

> In addition, `declare' form should be added to `defmacro' to specify
> which argument is considered as its body.

I have never used `declare' before. I looked it up in the Elisp manual
and read the docstring, but I couldn't understand how it specifies
which argument is considered the body. I'm also not aware of what this
does/why this is useful? (not a criticism, I just haven't learned this
yet).

> My opinion is that it should be inside
>    (let ((initial-input ...

This is a good idea -- done.

> and maybe even be a sibling of
>     (def (org-link-get-parameter type
> to keep related code more local.

This isn't possible, because that's a clause in a `let' call, which is
itself inside a `cond' clause, and the `CONDITION' of that clause uses
`type', so it has to be defined at a higher level.

> I have not tested, so I may be wrong in respect to the following. It
> seems, you rises priority of desc value that earlier was a fallback.
> The reason why I am in doubts, is that it seems, desc is initialized
> from current link description when point is withing an existing link
> and in such cases desc likely should be preserved. I can not say
> that I like that it is responsibility of all description functions
> to return the desc argument if it is supplied.

It's right that `desc' is initialized from current link description
when point is withing an existing link.

Previously, `desc' was only used when
`org-link-make-description-function' was nil. This seems to me a very
odd behaviour: preserve the current link description, but only when
`org-link-make-description-function' is nil. Especially considering
that `org-insert-link' is also used for editing already-existing
links. So in the original version, in some situations,
`org-link-make-description-function' had a higher priority than
`desc', which seems wrong.

Thanks,

Hugo

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From aac4b04e8448436dd2713116870ee86d87fa2005 Mon Sep 17 00:00:00 2001
From: Hugo Heagren <hugo@heagren.com>
Date: Mon, 28 Mar 2022 23:18:45 +0100
Subject: [PATCH] ol.el: add description format parameter to
 org-link-parameters

* ol.el (org-link-parameters): Add parameter `:insert-description', a
string or a function.
* (org-insert-link): If no description is provided (pre-existing or as
an argument), next option is to use the `:insert-description' (if
non-nil) parameter to generate one.

Default descriptions are predictable within a link type, but because
link types are quite diverse, are NOT predictable across many types.
A type-parameter is thus a good place to store information on the
default description.
---
 etc/ORG-NEWS |  7 +++++
 lisp/ol.el   | 73 ++++++++++++++++++++++++++++++++++++++--------------
 2 files changed, 60 insertions(+), 20 deletions(-)

diff --git a/etc/ORG-NEWS b/etc/ORG-NEWS
index 35af94f92..86128d100 100644
--- a/etc/ORG-NEWS
+++ b/etc/ORG-NEWS
@@ -322,6 +322,13 @@ purpose of the variable.  The replacement variable
 accepts =listings= and =verbatim= in place of =t= and =nil= (which
 still work, but are no longer listed as valid options).
 
+*** ~org-link-parameters~ has a new ~:insert-description~ parameter
+
+The value of ~:insert-description~ is used as the initial input when
+prompting for a link description.  It can be a string (used as-is) or
+a function (called with the same arguments as
+~org-make-link-description-function~ to return a string to use).
+
 * Version 9.5
 
 ** Important announcements and breaking changes
diff --git a/lisp/ol.el b/lisp/ol.el
index d4bd0e40c..5c702e33a 100644
--- a/lisp/ol.el
+++ b/lisp/ol.el
@@ -141,6 +141,18 @@ link.
   Function that inserts a link with completion.  The function
   takes one optional prefix argument.
 
+`:insert-description'
+
+  String or function used as a default when prompting users for a
+  link's description.  A string is used as-is, a function is
+  called with two arguments: the full link text, and the
+  description generated by `org-insert-link'.  It should return
+  the description to use (this reflects the behaviour of
+  `org-link-make-description-function').  If it returns nil, no
+  default description is used, but no error is thrown (from the
+  user's perspective, this is equivalent to a default description
+  of \"\").
+
 `:display'
 
   Value for `invisible' text property on the hidden parts of the
@@ -1804,11 +1816,14 @@ prefix negates `org-link-keep-stored-after-insertion'.
 If the LINK-LOCATION parameter is non-nil, this value will be used as
 the link location instead of reading one interactively.
 
-If the DESCRIPTION parameter is non-nil, this value will be used as the
-default description.  Otherwise, if `org-link-make-description-function'
-is non-nil, this function will be called with the link target, and the
-result will be the default link description.  When called non-interactively,
-don't allow to edit the default description."
+If the DESCRIPTION parameter is non-nil, this value will be used
+as the default description.  If not, and the chosen link type has
+a non-nil `:insert-description' parameter, that is used to
+generate a description as described in `org-link-parameters'
+docstring. Otherwise, if `org-link-make-description-function' is
+non-nil, this function will be called with the link target, and
+the result will be the default link description.  When called
+non-interactively, don't allow to edit the default description."
   (interactive "P")
   (let* ((wcf (current-window-configuration))
 	 (origbuf (current-buffer))
@@ -1818,7 +1833,10 @@ don't allow to edit the default description."
 	 (desc region)
 	 (link link-location)
 	 (abbrevs org-link-abbrev-alist-local)
-	 entry all-prefixes auto-desc)
+	 (all-prefixes (append (mapcar #'car abbrevs)
+			       (mapcar #'car org-link-abbrev-alist)
+			       (org-link-types)))
+         entry auto-desc)
     (cond
      (link-location)		      ; specified by arg, just use it.
      ((org-in-regexp org-link-bracket-re 1)
@@ -1859,9 +1877,6 @@ Use TAB to complete link prefixes, then RET for type-specific completion support
 	  (unless (pos-visible-in-window-p (point-max))
 	    (org-fit-window-to-buffer))
 	  (and (window-live-p cw) (select-window cw))))
-      (setq all-prefixes (append (mapcar #'car abbrevs)
-				 (mapcar #'car org-link-abbrev-alist)
-				 (org-link-types)))
       (unwind-protect
 	  ;; Fake a link history, containing the stored links.
 	  (let ((org-link--history
@@ -1958,17 +1973,35 @@ Use TAB to complete link prefixes, then RET for type-specific completion support
 	    (setq desc path)))))
 
     (unless auto-desc
-      (let ((initial-input
-	     (cond
-	      (description)
-	      ((not org-link-make-description-function) desc)
-	      (t (condition-case nil
-		     (funcall org-link-make-description-function link desc)
-		   (error
-		    (message "Can't get link description from %S"
-			     (symbol-name org-link-make-description-function))
-		    (sit-for 2)
-		    nil))))))
+      (let* ((type
+              (cond
+               ((string-match (rx-to-string `(: string-start (submatch (or ,@all-prefixes)) ":")) link)
+                (match-string 1 link))
+               ((file-name-absolute-p link) "file")
+               ((string-match "\\`\\.\\.?/" link) "file")))
+             (initial-input
+	      (cond
+	       (description)
+               (desc)
+               ((org-link-get-parameter type :insert-description)
+                (let ((def (org-link-get-parameter type :insert-description)))
+                  (condition-case nil
+                      (cond
+                       ((stringp def) def)
+                       ((functionp def)
+                        (funcall def link desc)))
+                    (error
+                     (message "Can't get link description from org link parameter `:insert-description': %S"
+			      def)
+		     (sit-for 2)
+                     nil))))
+	       (t (condition-case nil
+		      (funcall org-link-make-description-function link desc)
+		    (error
+		     (message "Can't get link description from %S"
+		              org-link-make-description-function)
+		     (sit-for 2)
+		     nil))))))
 	(setq desc (if (called-interactively-p 'any)
 		       (read-string "Description: " initial-input)
 		     initial-input))))
-- 
2.20.1


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From b8be9031c58a88e7d3294d587847b3edbbb43d36 Mon Sep 17 00:00:00 2001
From: Hugo Heagren <hugo@heagren.com>
Date: Sat, 16 Jul 2022 19:50:15 +0100
Subject: [PATCH] test-ol: tests for insert-description param when inserting
 links

* test-ol (test-ol-with-link-parameters-as): Convenience macro for
testing.
(test-ol-insert-link-get-desc): Convenience macro for testing.
(test-ol/return-foobar): Convenience function for testing.
(test-ol/insert-link-insert-description): Test for various values of
`:insert-description' in `org-link-parameters' (including
`test-ol/return-foobar').
---
 testing/lisp/test-ol.el | 88 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)

diff --git a/testing/lisp/test-ol.el b/testing/lisp/test-ol.el
index 429bb52ee..d2af972bd 100644
--- a/testing/lisp/test-ol.el
+++ b/testing/lisp/test-ol.el
@@ -19,6 +19,8 @@
 
 ;;; Code:
 
+(require 'cl-lib)
+
 \f
 ;;; Decode and Encode Links
 
@@ -625,5 +627,91 @@ See https://github.com/yantar92/org/issues/4."
     (test-ol-parse-link-in-text
         "The <point>http://foo.com/(something)?after=parens link"))))
 
+;;; Insert Links
+
+(defmacro test-ol-with-link-parameters-as (type parameters &rest body)
+  "Pass TYPE/PARAMETERS to `org-link-parameters' and execute BODY.
+
+Save the original value of `org-link-parameters', execute
+`org-link-set-parameters' with the relevant args, execute BODY
+and restore `org-link-parameters'.
+
+TYPE is as in `org-link-set-parameters'.  PARAMETERS is a plist to
+be passed to `org-link-set-parameters'."
+  (let (orig-parameters)
+    ;; Copy all keys in `parameters' and their original values to
+    ;; `orig-parameters'.
+    (map-do
+     (lambda (key _) (setq orig-parameters
+                      (plist-put
+                       orig-parameters key
+                       (org-link-get-parameter type key))))
+     parameters)
+    `(unwind-protect
+         ;; Set `parameters' values and execute body.
+         (progn (org-link-set-parameters ,type ,@parameters) ,@body)
+       ;; Restore original values.
+       (apply 'org-link-set-parameters ,type ',orig-parameters))))
+
+(defun test-ol-insert-link-get-desc (&optional link-location description)
+  "Insert link in temp buffer, return description.
+
+LINK-LOCATION and DESCRIPTION are passed to
+`org-insert-link' (COMPLETE-FILE is always nil)."
+  (org-test-with-temp-text ""
+    (org-insert-link nil link-location description)
+    (save-match-data
+      (when (and
+             (org-in-regexp org-link-bracket-re 1)
+             (match-end 2))
+        (match-string-no-properties 2)))))
+
+(defun test-ol/return-foobar (_link-test _desc)
+  "Return string \"foobar\".
+
+Take (and ignore) arguments conforming to `:insert-description'
+API in `org-link-parameters'.  Used in test
+`test-ol/insert-link-insert-description', for the case where
+`:insert-description' is a function symbol."
+  "foobar")
+
+(ert-deftest test-ol/insert-link-insert-description ()
+  "Test `:insert-description' parameter handling."
+  ;; String case.
+  (should
+   (string=
+    "foobar"
+    (test-ol-with-link-parameters-as
+     "id" (:insert-description "foobar")
+     (test-ol-insert-link-get-desc "id:foo-bar"))))
+  ;; Lambda case.
+  (should
+   (string=
+    "foobar"
+    (test-ol-with-link-parameters-as
+     "id" (:insert-description (lambda (_link-test _desc) "foobar"))
+     (test-ol-insert-link-get-desc "id:foo-bar"))))
+  ;; Function symbol case.
+  (should
+   (string=
+    "foobar"
+    (test-ol-with-link-parameters-as
+     "id" (:insert-description #'test-ol/return-foobar)
+     (test-ol-insert-link-get-desc "id:foo-bar"))))
+  ;; `:insert-description' parameter is defined, but doesn't return a
+  ;; string.
+  (should
+   (null
+    (test-ol-with-link-parameters-as
+     "id" (:insert-description #'ignore)
+     (test-ol-insert-link-get-desc "id:foo-bar"))))
+  ;; Description argument should override `:insert-description'.
+  (should
+   (string=
+    "notfoobar"
+    (test-ol-with-link-parameters-as
+     "id" (:insert-description "foobar")
+     (test-ol-insert-link-get-desc "id:foo-bar" "notfoobar")))))
+
 (provide 'test-ol)
 ;;; test-ol.el ends here
-- 
2.20.1