Add (alert) function to add system notifications?

[danielkrajnik]

Hi, I've forked the repo and trying to add (alert) function to alert the user with a desktop notification when new articles become available. Could you please let me know where in the code it can be added?

Sorry if it's a bit blunt question, but I can't trace the logic flow without breaking it.

[flocks]

That's a good question. I had never thought of it.

My first idea would be to update elfeed-notifier--update-hook:

(defun elfeed-notifier--update-hook (&rest _)
  "Hook that is run every time the elfeed db changes.

It takes `elfeed-notifier-query' filter and query the db with it to get
the number."
  (let* ((filter (elfeed-search-parse-filter elfeed-notifier-query))
         (func (byte-compile (elfeed-search-compile-filter filter)))
         (count 0))
    (with-elfeed-db-visit (entry feed)
      (when (funcall func entry feed count)
        (setf count (1+ count))))
    (setq elfeed-notifier-alert-mode-line
          (funcall elfeed-notifier-modeline-formatter count))))

The last part

(setq elfeed-notifier-alert-mode-line
          (funcall elfeed-notifier-modeline-formatter count))

is where we update the global variable elfeed-notifier-alert-mode-line with the number of unread elfeed entries. You could call the function that trigger the notification there

[danielkrajnik]

Thank you, I resorted to adding a hook in elfeed itself for now - it seemed to work although it stops working when I try to parse the entry (and I don't know how to debug it other than waiting for new articles each time).

If I won't get this to work in the end I will try the elfeed-notifier-alert-mode-line.

(add-hook 'elfeed-new-entry-hook
          (lambda (entry)
            (alert (prin1-to-string (elfeed-deref (elfeed-entry-content entry)))
                   :title (prin1-to-string (elfeed-entry-feed-id entry))
                   :severity 'high
                   )
            ))

[flocks]

and I don't know how to debug it other than waiting for new articles each time

Ah I see, may be you can:

• extract your lambda function in a named function, this way you will be able to refer to it in a (remove-hook) call

• try to use with-elfeed-db-visit The doc says

  Visit each entry in the database from newest to oldest. 
  Use ‘elfeed-db-return’ to exit early and optionally return data.

  (with-elfeed-db-visit (entry feed)
  (my-function entry)

This way you can grab one entry, and try to pass it to your function. Then you can use elisp/emacs debugging mechanism (check (elisp) Instrumenting ). I'm not an expert in elisp debugging, but I often use C-u eval-defun, it will make your function stop at each step of your function and you can inspect the current state

[danielkrajnik]

Thanks, I will try that, but another issue is that the hook doesn't always fire at all - it seems to work only every fifth time or so. I've developed it a bit further, but it's hard to tell what exactly may be causing elfeed to ignore it even when manually running elfeed-update with new feed entries appearing:

(add-hook 'elfeed-new-entry-hook
          (lambda (entry)
            (alert (prin1-to-string (elfeed-deref (elfeed-entry-content entry)))
                   :title (concat
                           (prin1-to-string (elfeed-entry-tags entry)) " - "
                           (prin1-to-string (elfeed-entry-feed-id entry)) " - "
                           (prin1-to-string (elfeed-entry-title entry))
                           )
                   :severity 'high
                   )
            ))