Project-level Leiningen Plugin

Question

In Leiningen versions 1.x.x I was able to define a lein foo task valid only in a single project by putting the following in that project's project.clj:

(defproject tester "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :dependencies [[org.clojure/clojure "1.4.0"]])

;; Create a task, "foo"

(ns leiningen.foo
  (:require (leiningen [uberjar :as uberjar])))

(defn foo [project & args]
  (println "Do something here first, then make the uberjar.")
  (uberjar/uberjar project))

You can get a little more information about this here:

http://nakkaya.com/2010/02/25/writing-leiningen-plugins-101/

In 2.x.x, I'm not able to do this anymore (i.e., I get 'foo' is not a task. It seems way, way overkill for me to have to start a separate project for this task. Is it still possible to define a task within project.clj for leiningen 2.x.x?

Answer 1

The short answer is "no", but it is still fairly easy to define a project level task: Add :eval-in-leiningen true to your defproject definition and move the task definition to src/leiningen/foo.clj.

Answer 2

You can do this by using .lein-classpath to point to a directory outside of src containing the tasks. For example, if you have the plugin in src/leiningen/foo.clj, you can do, at the project root:

$ mkdir tasks
$ mv src/leiningen tasks/
$ echo tasks > .lein-classpath

The reason you might want to avoid :eval-in-leiningen true is that it has some funny behaviors when you're trying to do AOT compilation for a main class. Specifically, you get:

Compilation failed: java.io.IOException: No such file or directory, compiling:(testproj/core.clj:1)

When trying to compile/run a even a simple test example. More information at:

https://github.com/technomancy/leiningen/issues/769