JRubyHelper.java

package com.ociweb.jruby;

import java.util.Iterator;
import java.util.Map;
import org.jruby.*;
import org.jruby.runtime.ThreadContext;

public class JRubyHelper {

  private IRuby ruby = Ruby.getDefaultInstance();
  private ThreadContext threadContext =
    Ruby.getDefaultInstance().getCurrentContext();

  public JRubyHelper() {
    setLoadPath();
  }

  private void addLoadPath(String path) {
    String expr = "$: << '" + path + "'";
    ruby.evalScript(expr);
  }

  public RubyObject callMethod(RubyObject receiver, String methodName) {
    return (RubyObject) receiver.callMethod(threadContext, methodName);
  }

  public void enableWarning() {
    // Gives lots of "Useless use of :: in void context" warnings
    // that don't make sense!
    ruby.setVerbose(ruby.getTrue());
  }

  public Object evalScript(String script) {
    return ruby.evalScript(script);
  }

  public static Object getAttribute(
    RubyObject object, String attributeName) {

    // The keys in this RubyHash are java.lang.String objects.
    // Are the values always java.lang.String object?
    RubyHash attributes =
      (RubyHash) object.getInstanceVariable("@attributes");
    return attributes == null ? null : attributes.get(attributeName);
  }

  public static void listInstanceVariables(
    String name, RubyObject object) {

    System.out.println("Instance variables of " + name + ":");
    Map vars = object.getInstanceVariables();
    Iterator iter = vars.keySet().iterator();
    while (iter.hasNext()) {
      Object key = iter.next();
      Object value = vars.get(key);
      System.out.println("  " + key + " = " + value);
    }
  }

  private void setLoadPath() {
    String jrubyLib = System.getProperty("jruby.lib");
    addLoadPath(jrubyLib);
    addLoadPath(jrubyLib + "/ruby/site_ruby/1.8");
    addLoadPath(jrubyLib + "/ruby/site_ruby/1.8/java");
    addLoadPath(jrubyLib + "/ruby/site_ruby");
    addLoadPath(jrubyLib + "/ruby/1.8");
    addLoadPath(jrubyLib + "/ruby/1.8/java");
    addLoadPath("lib/ruby/1.8");
  }
}

Copyright © 2007 Object Computing, Inc. All rights reserved.