It's been close to one year that I exclusively use Emacs for anything I do on a computer, be coding activities, be reading emails or man pages, be writing music sheets with GNU lilypond. I decommissioned all the specific tools (like vim, mutt) which all require a mental effort to remember the shortcuts of. Using Emacs is a guarantee to have a unified set of tools at hand.

Last week, after the announcement of version 30, I compiled Emacs mainly because wanted the new `use-package` ability to install package directly from a version control repository which is convenient when you maintain a fork of a package. For instance, now without adding any package to bring the feature to `use-package`, I have the following in my configuration:

(use-package chruby
  :vc (:url "https://github.com/stac47/chruby.el.git" :branch "main"))

I also discovered the etags-regen-mode which gives the possibility to automate the project tags generation.

Before this, I used to run etags manually from times to times mainly when a symbol was no more findable or when I was no more directed to the right place in a source file.

find . -name '*.rb' -print | etags -

And I created an interactive command to automatically search in visit the TAGS file in a project.

(use-package project
  :init
  (defun stac/project-tags ()
    "When in a project, visit the tags file at the root of the project."
    (interactive)
    (if (project-current)
        (let* ((proj-root (expand-file-name (project-root (project-current))))
               (old-tags-file tags-file-name)
               (new-tags-file (concat proj-root "TAGS")))
          (if (equal old-tags-file new-tags-file)
              (message "Tags file not changed: %s" old-tags-file)
            (visit-tags-table new-tags-file)
            (message "Tags file changed: %s -> %s" old-tags-file new-tags-file)))
      (message "No current project")))
  :bind
  (:map project-prefix-map
        ("t" . stac/project-tags)
        ("m" . magit-project-status)))

Now with the etags-regen-mode minor mode, I can automate all this. I just created a .dir-locals.el file at the root of the project I want the tags to be generated from with something like:

((nil . ((etags-regen-program-options . ("--language=ruby"))
         (mode . etags-regen))))

When the TAGS file does not exist, it will be generated the first time a file is saved on the project. Depending upon your project size, it may be a bit long and Emacs freezes. Hence, I feared some lag each time I saved a file, but it is not the case: only the modified file is passed to etags program to update the current TAGS file.

Adopted. Thanks all the Emacs developers for this jewel given to humanity.