Using Eclipse with JRuby Truffle

Eclipse is an alternative IDE for editing JRuby+Truffle. It provides much better feedback from the Truffle DSL annotation processor and actually keeps the project built at all times.

First, make sure the project is already built from the command line:

$ mvn

Using integrated Maven support

Create a new workspace in Eclipse (>= Luna).

Start by ensuring there is no leftover configuration:

$ rm -rf {core,truffle}/{.classpath,.settings,.project}

We can now import the two projects:

• From the main menu bar, select File > Import...
• Select Maven > Existing Maven Projects
• Select jruby/core directory as root directory (NOT just jruby)
• Click Finish
• Repeat with jruby/truffle as root directory

And now enable the Truffle annotation processor:

• Select the truffle project
• Right click and choose Properties
• Select Java Compiler > Annotation Processing
• Click on Enable project specific settings, then OK
• Click Yes to rebuild the project

Change the Output folder to not interfere with the Maven build for each project:

• Select the core project
• Right click and choose Properties
• Select Java Build Path and the Source tab.
• Uncheck Allow output folders for source folders
• In Default output folder: enter [PROJECT]/build.eclipse (with [PROJECT] replaced by core here)
• Select Yes when asked about removing generated resources in the old location
• Repeat with the truffle project

You shall be set!

Running from the Eclipse files directly

Use the tool/jruby_eclipse script to run directly from Eclipse .class files.
Any change in truffle Java or Ruby files will be available as soon as Eclipse finishes compiling.

$ tool/jruby_eclipse -X+T -e 'p RUBY_ENGINE'
"jruby+truffle"

The jt workflow tool automatically picks up that script over bin/jruby if you have
export JRUBY_ECLIPSE=true in your environment.