my new favourite language

Even though I’ve been programming in Groovy only for a couple of days, I really like it. It’s quickly becoming my new favorite language.

popiholla

Here’s a nice song from Chicane. Even though the songs lasts for 8 minutes, they’re totally worth it !

how to run your java class’s main method from jruby

Last night I wrote a Java class that performs a checkout from a SVN repository. I was able to integrate it with Groovy really fast, and was wondering how fast I could get it going with JRuby. I started to do some research on google, I downloaded the JRuby binary from http://dist.codehaus.org/jruby/, and I fired up jirb to do some quick testing.
Before I get to the JRuby part, let me add a little bit of information about the class I wanted to run: the only method I was interested to run was main, because most of the information was hardcoded in it.

So, I imported Java’s String class, hoping to build an array I could pass to main.

java_import "java.lang.String" do |package,classname|
   "J#{classname}"
end

This imports Java’s String class under the name JString, because Ruby has a String class as well. To create a JString object, you use Ruby’s regular object creation syntax :

JString.new("whatever")

Ok, so after I imported the java.lang.String class, I created an array of them:

args = [JString.new("argument"),JString.new("otherArgument")]

And I passed it to the class’s main method :

require "java"

java_import "java.lang.String" do |pk,nm|
  "J#{nm}"
end

java_import "SCli"
args = [JString.new("first_arg"),JString.new("second_arg")]
SCli.main(args)

Notice I imported the SCli class as well. That is my Java class. In order for the import to work, you should place the class in the CLASSPATH variable, or add the class file to your JRuby project’s lib folder and add that folder to the CLASSPATH. Also, if your class is inside a package, you should add that to the java_import line. Mine wasn’t in one.

Running this script gave me the following error :

main.rb:9: for method main expected [#<Java::JavaClass:0x9d5793>]; got: [org.jruby.RubyArray]; error: argument type mismatch (TypeError)

I was kind of hoping the array would pass for a Java array 🙂 . So, I started to search after this error message, and I got to the Calling Java from JRuby page. After a little bit of reading, I got it to work using the following script :

require "java"

java_import "SCli"
args = ["arg1","arg2"].to_java(:string)
SCli.main(args)

Nice,right?

groovy

I’ve spent some hours today reading about groovy, and I must say I really like it. The method intercept ability is awesome. I’ll be using it a lot from now on 🙂

great jar : ExpectJ

I’ve found a Java implementation of Tcl’s expect at http://expectj.sourceforge.net/. I wrote the following groovy script to test it :

System.in.withReader { r ->
	println "age please:"
	def age = Integer.parseInt(r.readLine())
	if(age < 20) {
		println "too young"
		System.exit(0);
	}
	println "you can go! name please"
	def name = r.readLine()
	println name
}

and here’s the code that uses ExpectJ to send input :

import expectj.ExpectJ

ExpectJ ex = new ExpectJ(10)
def shell = ex.spawn("groovy groovysimo.groovy")
shell.expect("age please:")
Thread.sleep(1000)
shell.send("25\n")
shell.expect("name please")
shell.send("geo\n")
shell.expectClose()
print shell.exitValue

It’s amazing how well it works!

scala syntax

I’m not very fond of the scala syntax.

globus – europa

nice

javascript documentation

Tonight, I had to write some JavaScript code, and I wanted to know what are some of the methods of nodes and other stuff. Because I didn’t want to be firebugging them I searched for online documentation.

I’ve found this : http://krook.org/jsdom/index-all.html. It seems complete as far as I can tell, it helped me accomplish what I needed to do.