WeigleWilczek Company Blog

1. Start the Selenium-RC server from Hudson
2. Compile the application and the test cases
3. Reinitialization of the database via DBUnit
4. Starting the Tomcat - application server
5. Running the Selenium test cases
6. Publish the test results in Hudson

There were a lot of interesting talks at the OSGi Day at W-JAX. If you are interested in the slides of my ScalaModules talk you can take it from here: http://www.slideshare.net/heiko.seeberger/wjax-09-scalamodules

The Scala Day at W-JAX was a great success: Many cool talks and lots of interested folks. If you are interested in the slides of my Lift talk you can take it from here: http://www.slideshare.net/heiko.seeberger/wjax-09-lift

Scala 2.8 will bring quite a lot of interesting new features, e.g. redesigned collection libraries, named and default arguments, support for continuations, a pimped REPL, etc. In the following I will show how named and default arguments enable us to write our Scala code even more concisely than before.

Let's flesh out an example in the 2.7 style: An order with an ID, order items and a shipping mode.

case class Order27(id: Long,
                items: List[Item],
                mode: ShippingMode)

case class Item()

sealed trait ShippingMode
case object StandardShipping extends ShippingMode
case object ExpressShipping extends ShippingMode
case object OvernightShipping extends ShippingMode

The order's ID shall be "mandatory" while we want to allow for defaults for the item list and the shipping mode. Hence we have to provide some auxiliary constructors.

case class Order27(id: Long,
                items: List[Item],
                mode: ShippingMode) {

 def this(id: Long, items: List[Item]) =
   this(id, items, StandardShipping)

 def this(id: Long, mode: ShippingMode) =
   this(id, Nil, StandardShipping)

 def this(id: Long) =
   this(id, Nil, StandardShipping)
}

As you can see, now it is possible to create an order by only giving the ID, e.g.

val order = Order27(1)

will create an order with the items set to the empty list (OK, this does not make too much sense in practice) and the shipping mode set to standard shipping.

On the one hand that's nice. But on the other hand the code is blown up significantly and it will take the reader some time to reason about the different possibilities to create an order, what is mandatory and what is optional with defaults.

Scala 2.8 let's us define default values with the class (or method) parameters by simply putting the default values behind the type.

case class Order28(id: Long,
                items: List[Item] = Nil,
                mode: ShippingMode = StandardShipping)

Now we can leave out the arguments for which defaults are defined, e.g.

val order = Order28(1)

will again create an order with no items and standard shipping. But this time there is no auxiliary constructor necessary to achieve that. Wow!

But how can we give the shipping mode and leave out the items? Looking at the order of the parameters in the primary constructor it is obvious that we have to give the item list before the shipping mode.

val order = Order28(1, HERE GOES THE ITEM LIST, OvernightShipping)

This is where named arguments enter the game. We simply prepend an argument value with its name, e.g.

val order = Order28(1, mode = OvernightShipping)

This way Scala knows how to get things right. Wow!!

Now that we have got Scala 2.7.6 I also updated the OSGi version of the Scala libraries. Please take it from the scala-tools.org Maven repository.

Nach den Erfolgen der Eclipse Banking Days veranstaltet WW nun eine Fachkonferenz zu Open Source-basierten Lösungen für Versicherungen. Der technologische Schwerpunkt liegt auf Eclipse, allerdings richtet sich die Veranstaltung primär an IT-Entscheider aus Versicherungen und IT-Dienstleistern für Versicherungen. Redner sind u.a. Mike Milinkovich, Excutive Director der Eclipse Foundation sowie Prof. Dr. Helten, Präsident des Bayerischen Finanz Zentrums
(-> Agenda).

Die Resonanz auf die ersten Ankündigungen ist hervorragend, so dass ich mich auf einen gut besuchten Tag mit spannenden Vorträgen und Gesprächen am Rand freue.

Zur EID Anmeldung

In my former blog post I reasoned about whether I should do a live demo of OSGi on Scala / ScalaModules at OSGi DevCon Europe 09. As I received very positive feedback from the community (thanx for that!) I decided to go for it. Now I just finished my short talk and everything (at least the hacking part) went fine. For those not able to attend, please find the slides (which try to give you some live feeling) at my Slidespace.

Some days ago Scala 2.7.5 was released and today I updated the OSGi version of the Scala libraries (see my former blog), too. I received some (positive) early feedback, but I am still very interested in knowing about any kind of real-world "production" usage.