how can I specify lein library dependencies depending on the jvm version number

Question

I'm working on a clojure library with a native lib dependency.

I don't want upgrade to jre 7 and lose support for jre 6.

I'm hoping that for users with jre 6 to include a different dependency version to users using jre 7. What is the best way to do that?

The issue can be seen here.

https://github.com/zcaudate/sigmund/issues/2

Answer 1

You can use Leiningen profiles or classifiers for what you are talking about.

Profiles

(defproject im.chit/sigmund "0.2.0"
  :description "System analytics for Clojure"
  :dependencies [[org.clojure/clojure "1.5.1"]]
  :profiles {:dev {:dependencies [[midje "1.5.0"]]}
             :jre6 {:jar-name "sigmund-jre6.jar"
                    :dependencies [[sigar/sigar "1.7.0-v20131027"]
                                   [sigar/sigar-native-deps "1.7.0-v20131027"]]}
             :jre7 {:jar-name "sigmund-jre7.jar"
                    :dependencies [[sigar/sigar "1.7.0-v20131027"]
                                   [sigar/sigar-native-deps "1.7.0-v20131027"]]}})

Node: The jre6 and jre7 profile names are arbitrary, and do not do anything beyond a standard lein profile. I just used meaningful names so their use would be obvious.

And, you can run tasks with both the jre6 and dev profiles combined by separating them with a comma, on the command line.

$ lein with-profiles jre6,dev test

If you want to jar them with a single command, you would separate them with a colon.

$ lein with-profiles jre6:jre7 jar

Classifiers

(defproject im.chit/sigmund "0.2.0"
  :description "System analytics for Clojure"
  :dependencies [[org.clojure/clojure "1.5.1"]
                 [sigar/sigar "1.7.0-v20131027"]
                 [sigar/sigar-native-deps "1.7.0-v20131027"]]
  :classifiers [["jre6" :jre6]]
  :profiles {:dev {:dependencies [[midje "1.5.0"]]}
             :jre6 {}})

In this case, the default profile would correspond to the current version, supporting JRE 7, and the :jre6 profile would be for the previous version.

$ lein jar
Created /Users/user1/sigmund/target/sigmund-0.2.0.jar
Created /Users/user1/sigmund/target/jre6/sigmund-0.2.0-jre6.jar

You would reference the "jre6" jar with the :classifier keyword in your :dependencies vector.

(defproject tester1 "0.1.0-SNAPSHOT"
  :dependencies [[org.clojure/clojure "1.5.1"]
                 [sigmund "0.2.0" :classifier "jre6"]])

This method is limited because, due to the way the pom file is generated, you cannot specify different dependencies for each classified jar. Other settings affecting jaring, such as source directories and AOT, should work.