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Hackathon Roundup

Posted on 24 May 2009 by David Chisnall

Last week saw the second Étoilé hackathon, hosted once again by the Swansea University Computer Science Department. They gave us a nice room overlooking the bay to hack in, and the use of their Internet connection for a bit. The hackathon officially started on Wednesday, but Eric arrived a day early:

Eric: After a few days of being a tourist in London and Bristol, I took the train to Swansea Monday evening. I neglected to print out a map which included both David's house and the train station, so I soon got lost and walked up Town Hill. I eventually found myself on the map, and arrived at David's much later than I should have - we were late for trivia at a local pub, so we headed there right away. I enjoyed meeting Davids' friends, answered (maybe) one trivia question, and tried some local beer. Afterwards, David showed me the results of his initial work on ProjectManager.

We spent some time on Tuesday hacking on LanguageKit on Eric's iBook. A few bits of LanguageKit are specific to the host platform and this was the first time anyone had tested it on PowerPC Linux. By Tuesday evening, LanguageKit (Smalltalk) was passing all of the tests on PowerPC Linux that it passes on other supported platforms. I pointed Eric at the right bits of code for implementing the PowerPC/Linux ABI, but he did the real work and improved the test suite a bit. I hacked on the Project Manager some more.

Nicolas had a traditional experience with British trains, and arrived later than anticipate, while Quentin had the opposite experience, resulting in their meeting at the station.

Quentin: On May 12, I was on the plane from Paris to Bristol to head to the new Étoilé hackathon edition, with my main luggage largely filled with cheese and saucisson. Seven hours later I was in Swansea one hour earlier than expected, so I decided to wait Nicolas a bit since our arrival were roughly in the same time slot. After a short taxi ride, we met Eric and David which were both actively working on getting LanguageKit working on Eric's iBook (a ppc machine).

Nicolas: We mostly spent this first evening discussing about various technical topics and which things we wanted to work on during the rest of the hackathon.

The evening wasn't just spent on technical discussions. We opened a couple of bottles, and each of us took it in turns to do some short demos of stuff we'd been working on.

Quentin: We celebrated Étoilé and the beginning of the new 2009 hackathon organized by David with plenty of good stuff: red wine, bread, saucisson and cheese. Nicolas was pretty quick to suggest the opening of the saucisson and I convinced him we couldn't eat it without some bread :-)

Quentin demonstrates EtoileUI

I had a cold the hackathon week, so was falling asleep shortly after midnight most days. The others stayed up a lot later, with Quentin putting together a simple DTP-like application as a demo on the first night.

On Wednesday, we walked down to campus and got our door access set up properly.

One of the things we've been planning for 0.5 is a unified message store and delivery system. Something similar was outlined in The Humane Interface, but without the implementation details. This is something that several of us are likely to implement parts of, so it was important to get a coherent model of how all of the bits would fit together.

Quentin: We ended the morning on the CoreObject unified message store (mail, im, rss etc.) which had been discussed several times on the lists over the previous year. We tried to work out all the involved interactions with GML on the whiteboard. We finally settled on a solution which is still to be implemented. The whiteboard result was the usual multi-layered arrow/box soup we all appreciate ;-)

Whiteboard Notes on 0.5

This year we managed to schedule the hackathon to occur during the university term. This had the advantage that it was possible to find food on campus, so a little while after we'd arrived we headed to an adjacent building for food. We then spent the rest of the afternoon hacking. I spent some time fixing various platform-specific bugs in LanguageKit then hacked a bit more on the Project Manager, while Quentin worked on EtoileUI:

Quentin: After the lunch, I was busy testing the last part of the new EtoileUI event handling on GNUstep. I was happily surprised to discover a large part was working almost flawlessly. In the middle of the afternoon, I started worrying on how I was going able to split all this work in small commits without spending a week on the merge. Although I had already committed many changes related to the new event handling model, the last chunk was a lot bigger and was tangled with other unrelated code I had to fix on the way. Various uncommitted new features/classes and the cross development on both Mac OS X and GNUstep was making everything harder.

Nicolas spent most of the time working on Code Monkey, the Smalltalk IDE build on top of LanguageKit. I spent some time on Wednesday afternoon writing code that could inspect a C stack and extract the Smalltalk StackContext objects, allowing for complete introspection of the stack.

Nicolas: Wednesday found us at the University, where we started hacking on EtoileUI, ETSerialize, Project Manager and CodeMonkey. Commits started to flow in as the day passed, and we ended up the day drinking some wine and eating a great cheese fondue with other Swansea friends.

In the evening, I made a fondu. Apparently this is a specialty of the region of France where Quentin is from (as is Reblochon, one of my favourite cheeses), so he watched very closely while I made it to ensure I wasn't doing anything, as he put it, 'heretical'.

Quentin: After the dinner, Eric convinced to push the big chunk in a single go. I was relunctant to do so, but Git decided to get in the way in the middle night and wrongly rename files randomly in my local branch when rebasing to the master. Happily Nicolas was sitting right next to me and he managed to get Git works a bit more sanely than I was able to. I finally gave up the last bits of my developer civility and pushed almost 10000 lines in a single commit. At the same time, I extracted few work-in-progress bits here and there to commit them separately. I added a very rough Magritte-like model description to EtoileFoundation with ETModelDescription and also ETPaneLayout which will supercede ETPaneSwitcherLayout and the PaneKit when finished. The model description stuff is demoed in the FormExample of EtoileUI were ETFormLayout uses to generate a basic form-like UI. The ETTemplateItemLayout infrastructure behind ETFormLayout is also used by the new ETIconLayout which was added during the hackathon. All that stuff is still quite unpolished… Don't expect too much from it.

On Thursday, we knew Fred Keifer, the GNUstep AppKit maintainer, was going to join us at some point, but weren't sure when. He and his girlfriend were spending some time hiking in Wales, and planned their trip so he could spend a bit of time with us.

So that Fred wouldn't get to university and find us absent, we got up early (I, once again, had gone to sleep around 12:30, but apparently everyone else stayed up for a few hours after).

Nicolas: Thursday we worked a bit at the university, but as our room was to be occupied for a couple of hours during lunch time, we went to eat in a small coffee place at the Swansea marina, walking from the University to the marina along the beach.

At the last hackathon, Quentin had somehow managed not to see the beach so it was nice to stroll along to the marina and drink some nice coffee and hack on a sofa while we enjoyed the free WiFi and good food.

Walking on the beach

Quentin: Most of the day was spent improving and debugging the new EtoileUI event handling which makes event handling logic reusable in form of tools/instruments (in the spirit Taligent and OpenDPI) and allow to dispatch semantic actions instead of input device specific events, time to time I side tracked to discuss other stuff like CoreObject or LanguageKit.

Discussion with Fred

Nicolas: In the late afternoon we finally had some news from Fred, who was waiting for us at the University, and we went back for a productive few hours, discussing many issues with him and some coding session (notably I ended up writing a live resize version of NSSplitView which turned out to be reasonably fast even on slow computers).

We had a discussion with Fred a while ago over the split between GNUstep and Étoilé and we wanted to talk in person about merging some of our changes (better horizontal menu support and theming, in particular) back upstream into GNUstep. Fred wasn't able to stay very long (and I ran away for a couple of hours for my weekly game of Ultimate Frisbee) but the discussions were productive and hopefully will lead to better collaboration between GNUstep and Étoilé in the future.

After Fred left we went back home and assembled CorePizza 2.0. This year we sent Nicolas to find the beer and he didn't get lost and Eric displayed an unsuspected skill in creating even pizza bases.

CorePizza 2.0

Quentin: David deserted around midnight. Eric, Nicolas and I were busy discussing how to improve CodeMonkey UI. What were the most important missing pieces now that debugging was underway with the new stack introspection support written by David yesterday. This was the night of CodeMonkey meets CoreObject. Sadly we gave up in the middle of the night on getting CodeMonkey works with CoreObject. In the end, Eric discovered two days later, the main problem was that the message name that was expected to trigger the persistency was mistyped :-/ … and we somehow missed it.

Friday morning started a bit later. We didn't have to get up for any specific reason. We did make it in to campus in the morning, but only just. The extra sleep was helpful for me, and my cold had almost gone away by Friday night.

Quentin: Friday was the talks day. I initially prepared a long talk on CoreObject, but the planning was 20 mn time slot, so I tried to quickly rearrange my slides with Eric's help to drastically reduce their number. In addition, I put together some slides on EtoileUI when Nicolas was preparing some slides to present GNUstep and Étoilé history.

Friday was the last day I was here, and we had talks planned for the afternoon. After quickly preparing some slides, we gave talks about the history of gnustep and étoilé, language kit, core object and étoilé UI -- all talks that you can now watch online :)

A lot of the morning was spent fixing up slides and then panicking that no one knew where the equipment were were planning to use to record the talks was. In the end we used the built-in iSight on Nicolas' MacBook Pro for video and my external one as a microphone.


Nicolas left shortly after the Friday talks finished, to recover from Nicolas' departure, Eric, David and I then went to the pub just outside the university campus to drink beers. We had an entertaining discussion on widely incoherent subjects: mountains and snow, the history of Canada, France and UK and a bit of Étoilé stuff here and there. LanguageKit and Étoilé on the web were the most discussed topics on the Étoilé side. We debated what was the best way to implement exporting EtoileUI-based applications as web applications and the various approaches we could take to do so… Then there was a long discussion which started with the organization of a ski-oriented hackathon in North America, turned into a wine oriented discussion (even French wine export troubles :-) then finally back to the holy Newton and the sacred Psion. David was motivated enough to take us for a walkthrough of the Psion 3A inside an emulator on his MacBook.

The Psion emulator was originally written for DOS, and runs inside DOSBox very nicely. I originally got my copy off a Computer Shopper (I think) cover CD, but you can probably find a copy online. The Psion did a lot of things very well, such as always saving state when you closed a document, so the user never really noticed the difference between applications and documents being closed and just being in the background. Anyone designing mobile devices should copy as much as they can from the Psion (and the Newton).

Friday was the last official day of the hackathon, but Eric and Quentin stayed until Monday morning, when they both headed off to Paris for Quentin to show Eric a sunnier bit of Europe.

Over the weekend, Eric and Quentin continued to hack on CoreObject and EtoileUI. Quentin tidied up the old Object Manager code which lets you visually inspect the AST of a Smalltalk program, while Eric did some work on the overlay shelf.

On Sunday we walked along the coast to Mumbles and had coffee and cakes in a sea-front cafe. For someone who lives amongst the patisseries of Paris, Quentin has a surprising obsession with Welsh cakes.

Quentin: That day I ate a lot of welsh cakes, scones and chelsea buns, that's almost all I can remember :-D As a last hacking objective, I got my generic Object Manager written in Smalltalk more or less working… the next step is now to improve CoreObject to get the whole thing more usable. The other part was mostly the continuation of the rewrite of various event-related methods in EtoileUI and a more exhaustive test coverage of the event handling.

On Saturday evening some friends of mine were playing in a tango band. Given the choice between coming out and dancing with beautiful women, or staying in and hacking, Eric and Quentin both chose to hack. Two nights in a row. When you next run Étoilé, remember their dedication…

Overall, we got a lot done. Nicolas did a lot on Code Monkey. It is now integrated with CoreObject for data storage and the final, intended, user interface was discussed in a lot of detail. Quentin and Eric did a lot with CoreObject and EtoileUI. Eric also did some hacking on LanguageKit, including some of the C++ bits that previously no one except me understood. I spent a lot of time tiding up bits of code, working on LanguageKit and the Project Manager, and finally got to spend some time improving the Objective-C 2 compatibility library. Not all of my commits are visible in Étoilé svn, because I also spent some time hacking on clang, including implementing support for Objective-C 2 declared properties on the GNU runtime.

Hackathon Statistics:

Total svn commits: 58. Total svn diff size: 20681 lines. GML diagrams drawn: 3. Welshcakes consumed: More than fit in a SmallInt.