This article is part of the “Meta Advent 2019” series. I’ve committed to writing a new blog post here every day until Christmas.

The State of CIDER survey was super insightful for me on many levels. Here’s one example - I realized that users might have missed some recent developments. A few people had commented it’d be nice if CIDER had a build-in “find usages (references)” functionality and funny enough - it already has this.

The functionality is based on ideas I’ve shared in the past and was introduced in CIDER 0.22. I guess for the majority of people the most interesting commands would be cider-xref-fn-refs (C-c C-? r) and cider-xref-fn-refs-select (C-c C-? C-r).1 The first command will show the usages of the function at point in a dedicated buffer and the second will show them in the minibuffer.2 Here’s how they look in action:

cider_find_usages.gif

Keep in mind the following limitations:

  • This works only for Clojure
  • It’s powered by runtime state analysis, which means it will show only data for loaded namespaces
  • It doesn’t (currently) find usages in lambdas
  • It doesn’t give us the precise locations where something is used, we only know that it’s used

On the bright side:

  • It’s super fast
  • It doesn’t require any static code analysis
  • It’s still more reliable than grep

The functionality is not perfect, but at least it’s there if you need it. As a bonus you get a quick way to navigate to all of the functions used by some function using cider-xref-fn-deps (C-c C-? d) and cider-xref-fn-deps-select (C-c C-? C-d). Those are pretty handy if you don’t want to jump to the source of some function to see what it refers to internally.

Don’t forget you also have a couple of third-party alternative:

  • The much more sophisticated AST-powered “find usages” provided by clj-refactor.el
  • Projectile’s “grep in project” (projectile-grep, typically bound to C-c p g)

That’s all I have for you today! See you tomorrow!

  1. I know those keybindings kind of suck because of C-?, but we ran out of good keybinding options a while ago. 

  2. If you’re familiar with cider-apropos you’ll notice the UI is very similar.