There is a library I rely on constantly in my day to day computing, at work and at home. This library is called dumb-jump.

I don’t see it is prized as often as Magit for example, which made me write this post.

Below I explain what it does but first, let me thank to Jack Angers and all the contributors. I have used this library for 10 years. It is one of the best computer programs I have ever used. There were periods when I was off Emacs during that time and the first thing I looked for in other editors was a plugin similar to dumb-jump.

What does it do

It jumps to definition of a function/method/class.

Here is my config for it:

(use-package dumb-jump
  :ensure t
  :config
  (add-hook 'xref-backend-functions #'dumb-jump-xref-activate)
  (setq dumb-jump-force-searcher 'rg)
  ;; use completion-read instead of a separate buffer with candidates
  (setq xref-show-definitions-function #'xref-show-definitions-completing-read))

Combined with rg it eliminated my need in LSPs or ctags/etags entirely.

Here is me using it on Emacs source code, which is big code base (click to view the video in a separate tab):

In this video I:

• press M-. to go to definition.
• In less than a second I get matching definitions that I can filter if necessary.
• I jump straight to the definition.

How does it work

It just greps the entire project for the symbol at point. The best thing about it is that with LSP for example it’s impossible (or rather I haven’t seen it working) to place my cursor over a function name in a comment somewhere and jump to it.

Like in:

/**
 * This test function is cool but
 * check another_function_name for more info
 */
 function test() {}

With dumb-jump - I can place my cursor at another_function_name, press M-. and I’m looking at the definition of it.

It works with ANY programming language.

Why not

ctags/etags

Every time a file is changed the ctags table must be regenerated. It can be automated but I think it’s unnecessary overhead.

LSP (Eglot)

I love LSP as a technology but I don’t want a background process to run on my machine while I’m working on a project. What if during the day I work on 10 projects, which is real for me at work for example. It will spawn 10 background processes for different languages that I have to mentally track (because I do mentally track what’s running in my computing environment).

The amount of RAM and CPU spent on this just feels too expensive.

Summary

If for some reason you haven’t tried this library - try. It’s so good.

I wish I can find better words on how grateful I am that it exists. Thank you!