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.
This depends on your branch:
on master

• Select the truffle project
• Right click and choose Properties
• Select Java Compiler > Annotation Processing
• Click on Enable project specific settings,
• Add lib/jruby-truffle.jar using Add External JARs, on the submenu Factory Path
• Click Ok and Yes to rebuild the project

on truffle-head

• Install the m2e-apt plugin.
• Select the truffle project
• Right click and choose Properties
• Select Maven > Annotation Processing
• Click on Enable project specific settings,
• Select the first option: "Automatically configure the JDT APT"
• Click Ok and Yes to rebuild the project

We must now import the layout generated files.

• Select the truffle project
• Expand in the file hierarchy: truffle then inside target and generated-sources.
• Right click on the generated-sources folder and select Build Path > Use as Source Folder
  Then,
• Select the truffle project
• Right click and choose Properties
• Select Java Build Path and the Source tab.
• In the list find truffle/target/generated-sources
• Select Included: (All) just below
• Click Edit on the right side.
• Click the Add button on the right side of Inclusion patterns
• Click Browse...
• Expand the file hierarchy: org then jruby, then truffle and runtime
• Select the runtime folder and click OK, OK again and Finish and a final OK.

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.

Ruby support

You can use Aptana Rails to be able to edit ruby files inside Eclipse. See http://stackoverflow.com/questions/12366924/how-to-use-eclipse-for-ruby-on-rails-ror