New Groovy Spec Lead Wednesday, June 14, 2006

Today the official announcement was made that Guillaume Laforge is the new Groovy JSR-241 Spec lead.

The whole Groovy community is anxious about the next few months hoping that 1.0 will be finished up. Congrats and good luck to Guillaume!

Groovy And JScience Sunday, June 04, 2006

I have been spending a lot of time investigating Groovy lately. I wanted to dig in to writing a Groovy Category so I started writing some code to support things like this...

def duration = 30.minutes + 2.hours

Before I got too far along there I discovered that John Wilson had already implemented a lot of that in his TimeCategory which is part of Google Data Support.

I had recently read a JNB article that Lance Finney had written on JScience and that gave me another idea. I decided to write a Groovy Category that would use JScience to support things like this...

def len = 2.kilometers + 500.meters

Since I wanted to do this as an exercise I decided to not even do any research to find out if anyone had already implemented something like this. I wanted to build this for my own benefit as a learning exercise. I started by expressing some of my own requirements in the form of a Groovy Unit Test like this...

class JScienceTest extends GroovyTestCase {

  void testConversions() {
    use(JScienceCategory) {
      def len = 2.kilometers
      assertEquals 2.0,    len.kilometers,  0.00001
      assertEquals 2.0E3,  len.meters,      0.00001
      assertEquals 2.0E5,  len.centimeters, 0.00001
      assertEquals 2.0E6,  len.millimeters, 0.00001
      assertEquals 2.0E9,  len.micrometers, 0.00001
      assertEquals 2.0E12, len.nanometers,  0.00001
      
      def len2 = 400.centimeters
      assertEquals 4.0E-3, len2.kilometers,  0.00001
      assertEquals 4.0,    len2.meters,      0.00001
      assertEquals 4.0E2,  len2.centimeters, 0.00001
      assertEquals 4.0E3,  len2.millimeters, 0.00001
      assertEquals 4.0E6,  len2.micrometers, 0.00001
      assertEquals 4.0E9,  len2.nanometers,  0.00001
    }
  }
  
  void testAddition() {
    use(JScienceCategory) {
      def len = 2.kilometers + 500.meters
      assertEquals 2.5, len.kilometers, 0.00001
    }
  }
  
  void testSubtraction() {
    use(JScienceCategory) {
      def len = 3.kilometers - 500.meters
      assertEquals 2.5, len.kilometers, 0.00001
    }
  }
  
  void testMultiplication() {
    use(JScienceCategory) {
      def len = 3.kilometers * 2
      assertEquals 6.0, len.kilometers, 0.00001
    }
  }
  
  void testDivision() {
    use(JScienceCategory) {
      def len = 42.meters / 3
      assertEquals 14.0, len.meters, 0.00001
    }
  }
}

My Groovy Kung Fu is still developing and I had not done anything at all with JScience before this. Even with those limitations I was able to get all of those tests passing in about an an hour.

Would you rather do this in Java...

Measure length = Measure.valueOf(50, SI.CENTI(SI.METER)).plus(Measure.valueOf(25.0, SI.METER));
Measure lengthInCentimeters = length.to(SI.CENTI(SI.METER));
System.out.println("length in centimeters is " + lengthInCentimeters.getEstimatedValue());

Or do this in Groovy...

def length = 50.centimeters + 25.meters
println "length in centimeters is ${length.centimeters}"

Isn't Groovy fun? :)