Yagni - You Aren't Gonna Need It.
Yagni is a static code analyzer that helps you find unused code in your applications and libraries.
I've written a blog post describing Yagni in greater depth here.
No matter how it happens, sooner or later an application is going to end up with unused code. It's time to call Yagni, the exterminator.
Yagni works by identifying all of the interned vars and declared Java classes
in the namespaces findable within your :source-paths
, and then walking the
forms of those vars and declarations.
As it walks the forms, it builds a graph of references to other vars and
declarations. It then searches the graph from a set of entrypoints (by default
your project's :main
method), and emits warnings for anything that it
couldn't find in the graph's search.
Merge the following into your ~/.lein/profiles.clj
:
{:user {:plugins [[venantius/yagni "0.1.7"]]}}
To have Yagni search for dead code, just run:
$ lein yagni
deps.edn
You can also use Yagni via a deps.edn
alias. Merge this with your deps.edn
:
{:aliases {:yagni
{:extra-deps {venantius/yagni {:mvn/version "0.1.7"}}
:exec-fn yagni.core/run-yagni
:exec-args {:source-paths ["src/clj"]
:main your.project}}}
And then run:
$ clj -X:yagni
Yagni works by searching your codebase from an initial set of entrypoints.
By default, Yagni assumes that the only entrypoint for your project is the one
listed in your project.clj's :main
key. Obviously, this is only useful for
applications and tools with CLI invocations.
As libraries, multi-main programs, and certain other types of projects either
tend to have no :main
or many entrypoint methods, you can instead enumerate
a list of entrypoints for your project in a .lein-yagni
file in the root
directory of your project. Feel free to take a look at the one in this project
as an example.
Running lein yagni
on the sample project located here will emit the following output:
$ lein yagni
=================== WARNING: Parents ======================
== Could not find any references to the following vars. ===
===========================================================
secondns/func-the-second
================== WARNING: Children ======================
== The following vars have references to them, but their ==
== parents do not. ==
===========================================================
secondns/notafunc
In general, bug reports, fixes, and code cleanup are always appreciated. Feature requests are liable to be subject to a bit more discussion.
When filing issues, please include the following:
project.clj
and your ~/.lein/profiles.clj
Copyright © 2018 W. David Jarvis
Distributed under the Eclipse Public License, the same as Clojure.