Tuesday, January 25, 2011

scala generics and eclipse autocompletion

The Scala 2.8.1 compiler doesn't create correctly the generics signature in some cases


Eclipse 3.6 is very strict about the signatures and it's autocompletion feature throws an exception when you work on a java project using scala code:


The issue is being fixed in both projects, but in the meantime I needed to work in eclipse with the akka library, and this issue is annoying.

I wrote a small tool which tries to fix the scala classes. Currently I tested it only on scala-library.jar, which contained the "orElse" method whose signature affected my setup. I don't know if it fixes all the problems, but I tried it on my project and eclipse  doesn't complain.

For now I only tried to put that jar in the eclipse IDE classpath, while keeping the original scala-library.jar in the executable classpath.

You can get the code at:


Thursday, January 13, 2011


A colleague of mine told me today that that his girlfriend woudln't believe that there was an optical illusion in the animated dancer image that you can find at: http://dl.dropbox.com/u/2520452/ballerina/ballerina.gif

I was just about to play with html5 canvas drawing, and so I wanted to try out to pilot the illusion with a small red ball which can rotate in both directions, following an elliptical path (an illusion of perspective) and appearing to disappear when going "behind" the dancer.

I don't know if it works for all, but for me this simple (and unprecise) animation, combined with the psycologial effect introduced by clicking on a "change direction" button, swaps the dancer's direction immediately in my head, or at least within one rotation.

Click here to se a demo

Source code on github