Along with the Script Engine Plugin (available from <http://plugins.jedit.org/> or from jEdit's Plugin Manager), JRubyScriptEnginePlugin provides jEdit with the ability to use JRuby (as a JSR-223 scripting engine) to run buffers and implement macros.

To build, install the Script Engine Plugin from the Plugin Manager. Then place JRuby's "complete" jar (e.g. jruby-complete-1.7.5.jar) in main/lib; the jar can be found at <http://www.jruby.org/download>. Then run ant as follows:

    ant -Djedit.install.dir=PATH-TO-JEDIT-INSTALLATION-DIR -Djedit.plugins.dir=PATH-TO-INSTALLED-PLUGIN-JARS

If building with JDK 7 or higher, you may have have a Java 6 JRE or JDK installed, and supply the Java 6 boot classpath, by adding

    -Djava6.boot.classpath=PATH-TO-JAVA-6-RT.JAR

Alternately, put a file called <build.properties> in this plugin's root directory or the one just above it, and include the lines:

    jedit.install.dir=PATH-TO-JEDIT-INSTALLATION-DIR
    jedit.plugins.dir=PATH-TO-INSTALLED-PLUGIN-JARS
    java6.boot.classpath=PATH-TO-JAVA-6-RT.JAR

Then ant can be called without settings these two properties on the command line.

Description of paths mentioned above:

    PATH-TO-JEDIT-INSTALLATION-DIR: directory where jEdit is installed (specifically its jedit.jar). With the OS X app, this is /Applications/jEdit.app/Contents/Resources/Java.
    PATH-TO-INSTALLED-PLUGIN-JARS: directory where plugin jars are installed (specifically ScriptEnginePlugin.jar); generally this will be ${HOME}/.jedit/jars (or ${HOME}/Library/jEdit/jars with the OS X app), or the jars subdirectory of the jEdit installation directory.
    PATH-TO-JAVA-6-RT.JAR: fully-qualified path to the Java 6 JRE/JDK's rt.jar file, or classes.jar in OS X.


The current version of this plugin uses JRuby 1.7.5. To use a different version, change the plugin.christopherson.eric.JRubyScriptEnginePlugin.jars property in main/resources/JRubyScriptEnginePlugin.props to reference the appropriate jar.

jEdit's build support dir is available from SVN at <https://jedit.svn.sourceforge.net/svnroot/jedit/build-support/trunk>; . I'm not sure if it can be downloaded except from SVN.