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∞ /notes/an-eclipse-rcp-digitization-wiki-with-e4-and-scala | 2010-04-18 | eclipse java programming scala
An Eclipse RCP digitization wiki with e4 and Scala
Cross-posted to: https://fsteeg.wordpress.com/2010/04/18/an-eclipse-rcp-digitization-wiki-with-e4-and-scala/
We have reached the first milestone of a new project I have been working on since November. The goal of the project (which is funded by the DFG) is to create a wiki for collaboratively improving the digitization of the Romansch Chrestomathy, a collection of Romansch texts. I think the domain of this project is very interesting, as it not only aims at improving access to cultural assets, but also takes the community wiki approach, which leads to a situation that is probably not the most common case in academic software development: users are part of the plan. But perhaps even more, I'm excited about the technical parts of the project, as we use both Scala for the core, non-UI components and e4 for the UI. Our first milestone for the initial beta (which we plan to release in summer) provides a basic local, single-user implementation of our system. It features basic search and page selection, editing and persistence, word-based edit history and highlighting of the currently selected word in the original scan.
As expected, combining two cutting edge technologies (Scala 2.8 and e4) does cause some inconveniences (e.g. I currently can't develop the Scala and the e4 code in the same Eclipse instance, as the Scala IDE for Eclipse does not yet support Helios and e4 won't run on Galileo).
But once I had a proper Ant build system in place (compile Scala sources, deploy as Jars into the e4 workspace, etc.), I was amazed about the concise code base we were able to build both for the backend and the UI with this approach.
To give some examples of what I liked about developing using Scala and e4 I've picked out a few lines from both sides of the current (not very large) code base.
On the Scala side, I really liked having features like case classes, XML support, and concise anonymous functions.
For instance, the XML serialization method of a Page defines that the full structure of the XML is to be filled with the XML representation of each Word of the Page:
def toXml = <page> { words.toList.map(_.toXml) } </page>Page, made only of the most recent form of each Word:
def toText = ("" /: words) (_ + " " + _.history.top.form)Word contains the given term, I checked each Page like this:
page.words.exists(_.history.exists(_.form contains term))Page in the top view (showing pages matching the search term). To listen to the selection of pages, the view defines a method with the following signature:
@Inject public void setSelection(@Optional @Named(SELECTION) Page page)Text widget here):
@Inject public void setSelection(@Optional @Named(SELECTION) Text word)Text widgets used in the edit view with CSS:
Text { font: Times 14px; background-color: #e8e8e8 #cccccc 60%; }