Library-provided `org-agenda-skip-function` builder?

[7ocb]

The org-ql is great for filtering the agenda, but as far as I can see it does not provide "out of the box" method to build filters suitable to be used in org-agenda-skip-function.

So I suggest to add one:

(defmacro org-ql-agenda-skip-if (query)
  (cl-labels (
             ;; recurses into list form and adds prefix
             ;; "org-ql--predicate-" for all functions except of "and", "or" and "not"
             (replace-predicate-names (form) 
               (if (listp form)
                   (let ((head (car form))
                         (tail (cdr form)))

                     (cons 
                      (cl-case head
                        ;; don't replace boolean expressions
                        ((and or not)
                         head)
                        ;; for other symbols add "org-ql--predicate-" prefix
                        (t (intern (concat "org-ql--predicate-" (symbol-name head)))))

                      ;; also replace for all args
                      (mapcar #'replace-predicate-names tail))
                     )
                 form)))
    `(lambda () 
       (save-excursion
         ;; org-ql predicates work best on the start of heading
         (outline-back-to-heading)

         (flet ((next-headline () (save-excursion
                                    (or (outline-next-heading) 
                                        (point-max)))))
           ;; if condition matched, go to next headline
           (when ,(replace-predicate-names query)
             (next-headline)))))))

This macro takes form, and adds "org-ql--predicate-" prefix to any symbol in function position except of "and", "or" and "not".

The usage is pretty straighforward:

(let ((org-agenda-custom-commands  
      '(
        ("t" "test" 
         agenda ""
         (
          (org-agenda-files '("/home/elk/test-for-org-ql.org"))
          ;; it can be just used inplace to build filter
          (org-agenda-skip-function 
           (org-ql-agenda-skip-if (and (tags "noise") 
                                       (not (tags "important"))))))))))
  (org-agenda nil "t")
)

test file:

* heading one :test:noise:
  <2023-10-03 Tue>
*** heading two :shmest:
    <2023-10-03 Tue>
*** heading three                                                    :shmest:extra:important:
    <2023-10-03 Tue>
*** heading four                                                     :shmest:
    <2023-10-03 Tue>

[yantar92]

"E.L.K." @.***> writes:

The org-ql is great for filtering the agenda, but as far as I can see it does not provide "out of the box" method to build filters suitable to be used in org-agenda-skip-function.

So I suggest to add one: ...

Another approach that also utilizes cache is https://github.com/yantar92/emacs-config/blob/master/config.org#archiving

[alphapapa]

The org-ql is great for filtering the agenda,

org-ql is more intended as an alternative to org-agenda, i.e. org-ql-search provides a similar view with similar features (the buffer is actually in org-agenda-mode) and better performance.

but as far as I can see it does not provide "out of the box" method to build filters suitable to be used in org-agenda-skip-function.

That's because it's designed to replace org-agenda's backend, which is very slow by comparison. The notion of a "skip function" is obsoleted by org-ql's query functionality.

Nevertheless, org-agenda provides some features which aren't implemented in org-ql, so we provide some ways to integrate with it, like org-ql-block.

So I'm not opposed to offering a feature like this, for circumstances in which org-agenda is still necessary.

An important caveat to note is that using org-ql's predicates in an agenda skip function will skip the optimizations that org-ql performs when running a query, so most of the performance benefits will be discarded. So it would generally be better to use org-ql-search directly.

yantar92's code example is an interesting way to use a cache to avoid re-running the same skip function more than necessary; I'd probably decline to add that to org-ql as it seems confusing to me, but it's a neat hack.

I'd also recommend writing this feature with a function rather than a macro, as generally there's no need for it to be one.

Finally, the function that rewrites the query's symbols should take the org-ql-predicates variable into account rather than doing it on all unrecognized symbols. (org-ql used to work that way, early in its development, but having org-ql-predicate-- prefixing all of the query symbols was unpleasant to look at. Now and then, however, I consider whether it should work that way internally, rewriting the symbols before executing the query rather than using fset around the running of each query.)

[7ocb]

@alphapapa

Please take a look:

It's now a function, not a macro (now it requires lexical bindings). Also it now converts by referring org-ql-predicates.

(defun org-ql-agenda-skip-if (query)
  (cl-labels (
              ;; recurses into list form and replaces all predicates which are
              ;; registered in org-ql-predicates
              (replace-predicate-names (form) 
                (if (listp form)
                    (let* ((fn (car form))
                           (as-predicate (alist-get fn org-ql-predicates))
                           (rest (cdr form)))

                      (cons 
                       (if as-predicate
                           (plist-get as-predicate :fn)
                         fn)

                       ;; also replace for all args
                       (mapcar #'replace-predicate-names rest))
                      )
                  form))

              (next-headline () (save-excursion
                                  (or (outline-next-heading) 
                                      (point-max)))))

    (let ((updated-query (replace-predicate-names query)))
      (lambda ()
        (save-excursion
          
          ;; org-ql predicates work best on the start of heading
          (outline-back-to-heading)

          ;; if condition matched, go to next headline
          (when (eval updated-query)
            (next-headline)))))))

[7ocb]

@alphapapa

An important caveat to note is that using org-ql's predicates in an agenda skip function will skip the optimizations that org-ql performs when running a query, so most of the performance benefits will be discarded

For my case, using provided function speeds up generating (actually _re_generating, first generating still rather slow) big weekly agenda 5-7 times, so maybe some optimizations are lost, but still this is much faster than what I had before. And also org-ql provides much more predicates.