kozikow blog

I switch between Mac/Linux and inconsistent ggtags/ctags configuration annoys me. The same .ctags and gtags.conf files do not work between OSes. This seems to be not a problem for dumb-jump

I use ag anyway, since it’s the best “grep” alternative and it can always fall-back to grep. Dumb jump lets me reuse my configuration.

I don’t have to think about rebuilding ctags. It’s especially relevant when I want to jump to code I just written. I don’t have to re-generate ctags after every function I just wrote.

Since dump-jump is built on two things I know well – elisp and regular expressions. It is much easier to navigate elisp, since I know debugger and language well. Debugging ctags/ggtags required me to learn tools I didn’t use in years The fact that dumb-jump uses familiar and “simple” tools it opens room for customizations like adapting regex to your custom Scala setup at your company.

Dumb jump asks about saving files. I personally like to not have to save files, but commit often using git. You can tell emacs to save all files before calling dumb jump, or focus out (if you care only about dumb jump remove the focus out).

(defun synchronize-like-intellij () (interactive) (save-some-buffers t))
(add-hook 'focus-out-hook 'synchronize-like-intellij)
(advice-add 'dumb-jump-go :before #'synchronize-like-intellij)

Through Emacs advice system you can tweak ag command before calling dumb jump and ag. What’s more, you can reuse flags between your helm-projectile-ag and dumb-jump-go. You can treat it as more powerful alternative to .dumbjump and .agignore.

(setq my-ag-ignored-patterns '("*.bak" "*.out" "*.csv" "*.pyc" "*.pdf" "*.png"))
(setq my-ag-flags (mapconcat  (lambda (ext) (concat "--ignore " ext)) my-ag-ignored-patterns " "))

(setq my-helm-ag-base-ag (concat "ag --nocolor --nogroup -W 100 " my-ag-flags " "))
(setq my-dumb-jump-base-ag (concat "ag " my-ag-flags " "))

(defun my-tweak-ag-per-project (&rest not-used-args)
  "Tweak the ag flags based on current file name"
  (let ((my-ag-project-flags (if (s-contains-p "/dotfiles/" (my-buffer-file-name))
                                 "--hidden"
                               "")))
    (progn
      (setq helm-ag-base-command (concat my-helm-ag-base-ag my-ag-project-flags))
      (setq dumb-jump-ag-cmd (concat my-dumb-jump-base-ag my-ag-project-flags))
      )
    )
  )

(advice-add 'helm-projectile-ag :before #'my-tweak-ag-per-project)
(advice-add 'dumb-jump-go :before #'my-tweak-ag-per-project)

Since the HN post mentions IntelliJ and ag – I was missing ability of helm-projectile-ag to search “symbol at point”. I wrote an elisp that does it, but it’s a bit hacky:

;; http://emacs.stackexchange.com/questions/10393/how-can-i-answer-a-minibuffer-prompt-from-elisp
(defun insert-symbol-at-point ()
  (if (> (length cached-symbol-at-point) 0)
      (insert cached-symbol-at-point))
  (remove-hook 'post-command-hook 'insert-symbol-at-point)
  )

(defun helm-projectile-ag-symbol-at-point ()
  "Search for number at point using helm-projectile-ag"
  (interactive)
  (setq cached-symbol-at-point (thing-at-point `symbol))
  (add-hook 'post-command-hook 'insert-symbol-at-point)
  (helm-projectile-ag)
  )

(global-set-key (kbd "C-s") 'helm-projectile-ag-symbol-at-point)
(global-set-key (kbd "C-S-f") 'helm-projectile-ag)

Emacs have generalized function checking if you are in the comment, syntax-ppss. It could be a good idea to implement it on top of it.

I think that adapting regex from https://leonard.io/blog/2013/04/editing-scala-with-vim/ should work.

For example, I like to be able to call helm-resume to switch to other completion, if i went to wrong place.

I have been toying with an idea of better sorting completions returned by ag/tags/projectile. I plan to implement smarter sorting for helm one day. It could work with ag,dumb-jump, helm-projectile-find-file, completions, etc.

dumb-jump runs additional regular expressions on result of your ag command. Such concept does not have to be unique to jumping to definition. I can’t think of good example where it could be useful, but I’ll update this post if I find something.