Ruby script to rebuild Eclipse .classpath

I'm in the process of rebuilding my Tapestry training workshop to use Eclipse instead of IDEA. One part of this is that I use the Maven Ant tasks to handle dependencies from an Ant build file. The end result are folders of JAR files:

lib/runtime

Runtime JARs

lib/runtime-src

Corresponding source JARs (where available)

lib/test

Test-only JARs

lib/test-src

Corresponding source JARs

With Tapestry + Hibernate, that's like 20 JAR files ... way too many to maintain by hand (especially across five similar projects). I mean, the Eclipse API for this is not designed for frequent changes ... I should be able to point Eclipse at a directory and say "take everything you find" (like I can in IDEA).

I tend to chase the Tapestry release, updating the Workshop project as each new Tapestry release is available. I can't be doing this by hand all the time!

What to do, what to do ... ah, a Ruby script! I've actually gotten very rusty with Ruby, so there's probably easier ways to do this, but the basics are there. I love that Ruby has lots of ways of quoting text that aren't intrusive:

#!/usr/bin/ruby
# Rebuild the .classpath file based on the contents of lib/runtime, etc.

# Probably easier using XML Generator but don't have the docs handy

def process_scope(f, scope)
 # Now find the actual JARs and add an entry for each one.
 
 dir = "lib/#{scope}"

 return unless File.exists?(dir)
 
 Dir.entries(dir).select { |name| name =~ /\.jar$/ }.sort.each do |name|
   f.write %{  <classpathentry kind="lib" path="#{dir}/#{name}"}
   
   srcname = dir + "-src/" + name.gsub(/\.jar$/, "-sources.jar") 

   if File.exist?(srcname)
      f.write %{ sourcepath="#{srcname}"}
   end
   
   f.write %{/>\n}
 end
end

File.open(".classpath", "w") do |f|
  f.write %{<?xml version="1.0" encoding="UTF-8"?>
<classpath>
  <classpathentry kind="src" path="src/main/java"/>
  <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
}

 process_scope(f, "runtime")
 process_scope(f, "test")
 
 f.write %{
  <classpathentry kind="lib" path="src/main/resources"/>
  <classpathentry kind="output" path="target/classes"/>
</classpath>
}
    
end

I integrated this script into my Ant build file, so that it runs after I pull down dependencies.

Once I get to the new workshop session on testing, I may need to update this to take account of testing (including compiling src/test/java to target/test-classes, etc.). Still, 45 minutes of tweaking (which would have been 10 minutes if I wasn't so rusty) will save me lots of time in the future, dividends payable immediately.