NSConference 2010 - day 2
February 03, 2010

Day two started with an illuminating session by Jeff LaMarche about the Objective-C runtime, and some of the nice dynamic and introspective things you can do with it, such as iterating through your own properties, methods, etc. A couple of days ago in Drew’s concurrency workshop I was thinking about the need for some good Objective-C wrappers for OpenCL, as there’s a lot of boiler plate setup code that you have to do. It’s there for flexibility, but probably you do the same thing for most apps, so why not wrap it in some simpler objects. Some wrappers probably already exist somewhere, but it struck me that one of the techniques Jeff was describing would be perfect for supporting OpenCL kernel parameters. Instead of having to write code to poke the parameters into the kernel, wouldn’t it be great to just be able to subclass an OCLKernel class, define some properties on it, and automatically have setters implemented which loaded the property values into OpenCL, and getters which retrieved the values.

Next up was Andy Finnell, giving a session that was supposed to be about Core Image, but was actually more about OpenCL. Everyone reported that this was an interesting session, but I sort of got distracted because I was starting to hack together the OpenCL wrapper classes that I’d thought of in the previous session (I’ll post them up when I’ve done them). Having said that, if there’d been more actual OpenCL in Andy’s presentation I would probably have been drawn back in to it, but actually he mentioned himself that he’d wrapped the calls in a class hierarchy, and went on to focus on the physics, which whilst interesting wasn’t really of much general use. In the end, from what I heard, it was more about the physics of watercolour pigments and their interaction with paper - which whilst interesting, wasn’t really what I was there for!

Next up were two half-length sessions thrown together at short notice because one of the other speakers had to drop out.

First a quick overview of some source control systems by Dave Dribin. This was a tough job in such a short time, and I felt that it was a bit light on the right details. He spent too long on the purpose and history of version control, and not enough time on a discussion of the idioms that we use in the real world, and how they do or don’t fit into the models provided by Svn, Git, Mercurial or Perforce. Not that the history and purpose isn’t interesting, but in half an hour you can’t really do it justice on its own, so it was probably better to focus on telling people who understand version control and use one every day how the one they use compares to the other major options. I found this frustrating because I use a very large Perforce system at work (it’s pricey, but excellent, and I’m not convinced that the other systems could do what we do with it), and run a Subversion server at home (which is simple, but I want to change to something else, probably git or mercurial). What I really wanted was answers to some fairly complex situations that happen in the real world - like “how well can you manage multiple concurrent release branches”, “how does it cope when you have twelve devs continuously hacking on a branch”, “how well does it deal with large amounts of data - e.g. graphics assets”, and “how does system XYZ recommend managing your own shared library modules that are used by more than one project that you also have under source control?”. None of which were really answered.

This was followed by a very whistle stop tour of code signing from Graham Lee. Although brief, this was actually useful as he told me how to do something that I didn’t know how to do before. He delivered it with his customary humour, and the session was most notable for re-christening Wolf Rentzsch as “The Dog Spanner”.

After another excellent lunch we had our final “proper” session, from Aaron Hillegass, on data persistence. He started with an excellent set up, posing some interesting questions about how relevant the file system is any more, and whether “the file” is actually dead, to be replaced largely by the data cloud. Quite possibly, he suggested, our local machine hard drives are just local caches from here on in. I think this is a great topic which could have been explored further - for example, if files on our local hard drive are just caches, shouldn’t we be trying to find ways to structure them better so that they can be synchronised with the cloud in a non-monolithic way. One big fat 10Mb file is a bit hard to sync unless you’ve got a detailed schema describing the internal structure, and permission to mess with it. Anyway, I think that side could have been explored further, but Aaron switched tack somewhat to talk about the BNRPersistence framework that he’s created. Which was an interesting topic in it’s own right.

Finally, we had the “Cocoa Rumble”, which was a light hearted competition between three teams composed jointly of the session presenters and volunteers from the crowd. I didn’t really feel that it worked that well this year, despite generating some good presentations at the end. Somehow I don’t think we’ve yet managed to find a way to end NSConference which matches the old “Stump The Experts” sessions at WWDC (which were kind of cool back in 1993 when I first went, and still good fun back in about 2002 when I last went!).

So there you have it - two days of great Mac related sessions. I’ve learnt a fair amount, met some nice people along the way, and had a splendid time. I’ve eaten far too much, and drunk lots of bad beer and bad cider. And tomorrow, there’s another whole day of iPhone stuff. Phew…

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