Hard CIDER: Find Usages
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 built-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:
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 toC-c p g)
That’s all I have for you today! See you tomorrow!