EclipseCon Europe - Join the Party!

Only one week until EclipseCon Europe 2012 will take off in Ludwigsburg. Again hundreds of Eclipse enthusiasts will strive for the next record of highest WiFi usage ever in the Swabian city with the largest baroque castle in Germany. From Oct 23 to 25 the Forum am Schlosspark will transform to a vibrant place of technical discussions, entertaining sessions and socializing. Thanks to the huge amount of submissions from the Community the program committee managed again to tie up three days of deep technical content about Eclipse, the framework and the ecosystem, about its past, present and future (actually not to much about the past, but that's a good thing, isn't it?).

I will have the pleasure to talk about a potpourri of different topics that each cover some field of interest of mine.

Tue 9:00AM - 12:30PM: Getting Started With Xtend
My conference starts on Tuesday Morning at 9:00 in the Schubartsaal. Sven and I give a tutorial about Xtend where you will have the chance to get your hands dirty on interesting and challenging programming problems and puzzlers. You should not miss that one!

Wed 2:00PM - 2:30PM: Xtext - Best Practices
On Wednesday I will share lessons learned when using the Xtext framework. I will cover a number of topics that I encountered in the Xtext newsgroup and other noteable things that can be important in your daily work with Xtext. If you are already familiar with this cool framework and want to know more about it or just contribute your own experience to the discussion, stop by in the Theater on Wednesday, 2:00 PM.

Thu 10:30 - 11:00: Java Performance MythBusters
The submission of this talk was inspired by a talk by Arno Haase that I attended at the JAX (Arno greatfully gave permission to hijack the title of his talk - thanks for that!). In this session I want to shed light on some myths about Java's performance and often recommended Dos and Don'ts. Come to the Schubartsaal on Thursday 10:30 and I bet you'll be surprised.

Thu 1:30PM - 2:00PM: Null-Safety on Steroids
Even though the new annotation based null-ness analysis of Eclipse Juno is often very helpful, I am not really fond of the implications that their design has on a reasonable sized code-base. In my last session at this year's ECE I want to share my impressions about null-safety and static analysis. Join me in Silchersaal, Thu 1:30PM if you want to learn about different approaches to tackle the infamous NullPointerException.

Of course there are other interesting sessions, too, e.g. John Arthorne raises the question about The future of Eclipse. The marriage of JavaFX and e4 seems to be a hot topic, too, since JavaFX is a quite powerful rendering technology. And naturally I'm excited about other Xtend and Xtext related content.

If you are still not convinced, take a look at the schedule yourself and make sure you join the party!

Revisited: Xtend @ JavaOne 2012

My talk about Xtend at this years JavaOne is now available in the content catalog on the conference website.

After a quick motivation and the answer to the obvious question "Why the heck did these guys develop yet another JVM language?", I gave a short overview on the basic ideas and design principles behind Xtend. Next up was a demo with different code snippets. Basically it was a walk-through with the examples that can be loaded into everybody's Eclipse as soon as the Xtend SDK is installed. Just select New -> Example... -> Xtend Introductory Examples and there you go.

The last part of the talk was about Active Annotations, a unique feature that will be part of the next version of Xtend. To put it into a few words it's Java's annotation processing on steroids. Active annotations may contribute to the translation of Xtend code to Java and even modify the result of that process. They allow to create additional types, use information from other resources or validate the Xtend code according to the annotation's semantics. Along with the powerful means to design creative and expressive APIs and the tight integration with Xtext languages, Xtend's exceptional support for domain-specific languages is raised to the next level by Active Annotations. Stay tuned for more information!

Xtend @ JavaOne 2012

This year, I will attend the JavaOne for the very first time and I'm really looking forward to it since I expect it to be a great conference (almost as good as EclipseCon, I'd say ;-). I'm especially excited about the fact, that my session about Xtend got accepted and therefore I will have the chance to give a talk about that great language which we are working on in Kiel, Germany. The session will be on Tuesday, Oct 2, 10:00 AM - 11:00 AM @ Hilton San Francisco - Golden Gate 6/7/8.

Don't expect a talk about language theory or something. I will only bring a few slides to give a brief introduction and insight into the ideas and philosophy behind Xtend. The bigger part of the session will be pure live coding. Xtend plays nicely with all these cool frameworks in the Java ecosystem so expect a variety of interesting code snippets. And as a guy from northern Germany I will even prepare an example that has to do with beer. And singing. Just kidding, I won't do that to you.
So if you are at JavaOne this year, make sure to stop by to learn more about Xtend.

Xtend @ EclipseCon Europe 2011

The second day of the EclipseCon Europe 2011 is almost over and so far it's been a very nice conference. The sessions that I attended were quite interesting and the 10th birthday party was very nice. The folks from the Eclipse community are really sociable!

Now I'm looking forward to my session about Xtend - which I'm very excited about. Xtend is a programming language that is made for Java developers. With support for closures, extension methods or template expressions it allows to use some of the pending Java 8 features right now. In that sense it serves as a complement to the state of the art programming language - and integrates nicely with all the existing libraries and APIs. But first and foremost it's a real pleasure to write implementation code again, especially for scenarios where Java doesn't shine too bright. If you want to learn more about Xtend, please come to my session in the Theater Stage on Friday, 14:00.

Customizing Content Assist with Xtext

As basically every part of Eclipse Xtext, the content assist API provides a reasonable default behavior and is greatly customizable by means of dependency injection. This blog post demonstrates, how easy it is to create own completion proposals with this API.

For the sake of simplicity, I'll use a grammar that fits in a single line:
<br /> Color: 'color' rgb=STRING;<br />
It allows to define exactly one color literal and the syntax is not really strict about the literal's format. Valid input files are considered to look like color "0,0,0" or color "255,255,255".

Now comes the fun part: The proposal list for the rgb string should provide some frequently used values, e.g. literals for black or white.

Therefore I have to customize the proposal provider. Xtext already provides an empty stub implementation that will take the custom code. In order to change the proposals for the rgb-value in the parser rule Color, the method completeColor_Rgb(..) has to be overridden. JDT's content assist or the quick outline in the proposal provider implementation helps to find all suitable entry points.
<br /> @Override<br >public void completeColor_Rgb(EObject model,<br > Assignment assignment,<br > ContentAssistContext context,<br > ICompletionProposalAcceptor acceptor) {<br > acceptor.accept(createCompletionProposal(<br > "\"0,0,0\"", "black",<br > null /*getBlackImage()*/, context));<br > acceptor.accept(createCompletionProposal(<br > "\"255,255,255\"", "white",<br > null /*getWhiteImage()*/, context));<br >}<br />
Two lines of code later, I can already insert literals for black or white:

However, there are far more possibilities than simply creating plain vanilla proposals. The overloaded factory method createCompletionProposal(..) returns an instance of the ConfigurableCompletionProposal which has a quite powerful API. It allows to change the appearance of the display string, I can set additional hover information, enable linked edit modes for the custom proposal or make it auto-insertable to name only a few.

The next example uses an own ReplacementTextApplier to hook into the actual moment, when the proposal is applied:
<br /> @Override<br >public void completeColor_Rgb(EObject model,<br > Assignment assignment,<br > final ContentAssistContext context,<br > ICompletionProposalAcceptor acceptor) {<br > ConfigurableCompletionProposal pickColor =<br > (~cast~) createCompletionProposal("Pick color...",<br > context);<br > if (pickColor != null) {<br > pickColor.setTextApplier(<br > new ReplacementTextApplier() {<br > @Override<br > public String getActualReplacementString(<br > ConfigurableCompletionProposal proposal) {<br > Display display = context.getViewer()<br > .getTextWidget().getDisplay();<br > ColorDialog colorDialog = new ColorDialog(<br > display.getActiveShell());<br > RGB newColor = colorDialog.open();<br > return "\"" + newColor.red + "," + <br > newColor.green + "," + <br > newColor.blue + "\"";<br > }<br > });<br > acceptor.accept(pickColor);<br > }<br > ..<br >}<br />
You'll guess that already from the code: This implementation allows to pick the color by means of a color chooser after the proposal has been selected, but see yourself:

There are plenty of other interesting APIs and services around the code completion in Xtext that are worthy of talking about (e.g. the prefix matcher, which Alex covered in his recent post), but I'll leave them for another post.

Xdoc: A Documentation Language For Eclipse Frameworks

Xdoc is a small markup language that allows to create code centric documentation in a very convenient way. The documents can be rendered to HTML, to Eclipse Help files and to a printable PDF.
Besides the usual markup tags to emphasize text, add images and tables or create structures such as chapters, sections and the like, there are two unique features of Xdoc that I want to highlight.

First of all, it is possible to refer to Java types in a way that allows to statically validate these references. This feature comes very handy as soon as you want to describe important hooks of a framework or codebase. The references will be rendered as hyperlinks to the online Javadoc and if there is a public source repository, a second link points directly to the code.

The second interesting feature is related to code snippets in the documentation. It is often valuable to document some usage patterns for a certain class or interface by example. However, making these snippets easy to read and achieving the familiar look of an Eclipse editor with syntax coloring and the like often requires a lot of effort. Xdoc simplifies this greatly. You just define a set of keywords for a language and the renderer will take care of the highlighting for your code snippets in a consistent manner. This is a big improvement when it comes to the appearance of your help files.



To provide just a few technical details: Xdoc was build with Xtext. That is, the Eclipse editor supports all the nice features that you are already familiar with from other editors. The code generator which creates the Eclipse Help files on the fly is written in Xtend which in turn is implemented on top of Xtext 2.0. Xdoc itself was used to write the Eclipse Help for Xtext and Xtend. Actually, the Xtend Help was written before Xtend was implemented, but that's another story. The chicken or the egg? Things get a little blurry these days... Did I mention that Xtext was used to implement Xtext?

New Features In The Xtext Grammar Editor

Besides the huge new features like the Xbase library, the new Xtend and the cross language refactoring capabilities, we made sure that we still find some time to implement small refinements and improvements in Xtext's core. Some of them may be not too obvious but I'm pretty sure they will actually have some impact on the overall user experience when building new languages with the framework. This blog post is about two nice additions in the grammar editor that are available in Xtext 2.0 with Eclipse Indigo.

Improved content assist

You'll often want to create a concrete syntax for an existing EPackage which was somewhat cumbersome in the past since it involved copy and paste of the namespace uri. The good news is:
Adding imported packages was greatly simplified. It's now far easier to find the actual EPackage that you want to use in your grammar because content assist matches for the more selective last segments of the namespace uri, too:



Speaking about imported packages: If you want to override a rule from another grammar, you can now use content assist to create a stub for that. The editor will take care of necessary import clauses:



Quick Fixes

If your workflow is similar to mine, you'll usually develop a grammar top-down. This implies that your grammar often contains a bunch of unresolved rule calls since the invocation of a parser rule appears before the rule itself is written. A new quick fix allows to create stubs for unknown rules as soon as you refer to a rule which does not yet exist:



I hope you like these small improvements as much as I do!