Living Code

[Updated 2006-08-20 to add links. All (most?) presentations are being posted on the proceedings page]

Last weekend I attended the Vancouver Python Workshop here in town. I love this conference because it’s small and local, but attracts a great crowd. There were a few folks I know mainly from the edu-sig mailing list. Guido was there to give the keynote, I got to talk with Ian Bicking a fair bit, and I had never realized that Toby Donaldson is a fellow Vancouverite.

Friday night: Keynotes

Guido (van Rossum, creator of Python, for anyone reading this who is not soaking in Python every day) gave a keynote on the state of the upcoming Python 3000. Since I make an effort to keep up with this there wasn’t much in the way of surprises here, but it’s always good to hear it from the BDFL’s mouth. I’m excited by what’s happening in Python lately, both in language changes and in the libraries, and I think Python 3000 will be a move in the right direction when it comes.

Jim Hugunin, initiator of the Numeric extension, Jython (Python on the Java virtual machine), and most recently IronPython (Python on Microsoft’s dotNet virtual machine) also gave a keynote. He showed how having Python running in the same runtime as your C# code allows you to have stack traces all the way down, which is an advantage over PyObjC. It also helps to be binding to a language which is garbage collected. In PyObjC they go to lengths to make the runtime behave like garbage-collected Python, but there are still some edge cases that can sneak in and bite you. Of course, Apple’s announcement of garbage-collected Objective-C in XCode 3 next year should fix that. Jim’s an engaging speaker and seems like a really nice guy. And since both Google (”do no evil”) and Microsoft (”evil empire”) were represented, balance was maintained in the Force.

After the keynotes there was a reception at the Steamworks brew pub, which is a great place. Staying up late drinking may not be the best way to kick off a conference that starts at 8 am the next day though. I was home by midnight, but I heard from many others that they were out until 3 am. Ouch.

Saturday: Workshop Day One

This was an intense day for me. I was scheduled to give a presentation, but then Paul (Prescod, my friend and co-worker, and one of the conference organizers) asked me to also give a lightning talk and be on a panel discussion. Since I didn’t have time to prepare much for these I was a bit nervous. On top of already being nearly sick with stage fright getting ready for the presentation I did prepare for.

Guido hadn’t had time for questions after his keynote the night before, so the conference kicked off with a Q&A session for him. After that was the lightning talks, and I gave the first one. Aside from not having time to prepare, I had never given a lightning talk before. I demo’d Drawing Board, the animation tool I’ve been working on for my kids, which filled my five minutes pretty easily. I got some nice feedback about it too, which is especially gratifying since after I’ve been working on something for awhile I tend to only see all the problems I know it has, rather than what is good about it. Drawing Board has been a real struggle for me, both in learning PyObjC and the “Cocoa Way” of doing things, and trying to push it into new territory, so I was pleased with how its first public demo was received.

After the lightning talks I attended the beginning of Paul’s tutorial for newcomers to Python to try and pick up some tips. After lurking on the edu-sig mailing list, I’m trying to organized some Python classes at my daughter’s school for the kids there. Paul’s approach was more towards people already programming in other languages, so I didn’t get much there that I could use, but it gave me some things to think about at least.

Ian Bicking’s talk on WSGI got extended from one 45-minute slot to two, and I only got so sit in on the first half, because it overlapped with my presentation. I loved his hand-drawn slides and his take on the “Internet is a series of tubes” meme. He’s a good presenter and WSGI is important stuff for Python, giving it the kind of basic web framework that Servlets gives to Java, which Python has desperately needed for a long time. Now if I could just wrap my brain around Paste I think I could achieve web enlightenment…

My talk, “OS X, Python, and Kids” went well. I used the whole 45 minutes (not like last time I presented when I went nervously through my presentation in 10 minutes and was then left embarrassed on stage), took some good questions, and people seemed to be engaged. I’ve posted my slides, with notes based on what I was talking about during the presentation, here (3MB PDF). The feedback from this presentation, where I used several of my projects as examples of what you can accomplish with PyObjC, was very good, at least from the folks who came up to me. A couple of people even sounded like they were on the fence about whether to switch to Macs and I might have given them a push.

After my talk, and lunch, was the panel discussing how to embed C, C++, C#, and other languages in Python. We had Jim Hugunin (IronPython), Tom Weir (using SWIG on a proprietary project), Samuele Pedroni (of PyPy), and me. There was no moderator, and while I’ve followed the various tools to wrap libraries for Python, and I’ve used a lot of libraries that are wrapped for Python, I haven’t actually done much wrapping myself, so I tried to be a moderator and get the conversation going. SWIG seemed to be used by the most people in the room, and while as a user of SWIG I’ve struggled with it, since any project that uses it seems to be dependent on a very specific version which you then have to find, download, and install. So I’m not a big SWIG fan. On the other hand, folks who use it for wrapping C code can freeze the version they’re using and more or less rely on it, so it works great for them (although I guess debugging is still a bear). I still thing SWIG is part of the problem, not part of the solution.

At the end of day one was a great BBQ at Locarno Beach. Daniela and I took the kids, then we stayed on the beach to watch the final night of the Celebration of Light fireworks. It was Mexico’s turn to light up the sky and they did a spectacular job, winning the four-night competition with Italy, China, and the Czech Repulic. So then there was an encore display, and then we tried to get home through the gridlock that follows fireworks in Vancouver. We got home by midnight, washed the sand of the kids, and put them to bed.

Sunday: Workshop Day Two

After two late nights (for me) and early mornings (for weekends) I’m beginning to feel really beat. I’m also coming down from the adrenaline high I was on yesterday, before and after presenting. I was also distracted by trying to implement the Turtle module in the standard library from Tkinter to PyObjC (and simultaneously port my Kutia turtle program from Tkinter to PyObjC). I actually got pretty far with it, but probably need to post some questions on the PyObjC mailing list to get it finished.

The morning started with a status report on PyPy from Samuele Pedroni, one of the furthest travellers to the conference, coming in from Italy. I’m fascinated by the progress PyPy has made, going from thousands of times slower than CPython to only a couple of times slower. PyPy is Python implemented in Python, specifically implemented in a subset of Python which can be efficiently compiled to C, called RPython. This is similar to how Squeak Smalltalk is implemented (a small, compilable subset of Python is used to implement the rest). The advantage of PyPy is that because the language definition itself is relatively high level, they can quickly implement all kinds of interesting things, like Stackless Python, compiling python to dotNet or Java, even experimenting with compiling Python to Javascript. It’s a very interesting project and a lot of fun to watch. I’m rooting for them.

Next was Wilson Fowlie’s presentation on PyParsing. I had lunch with Wilson and he’s a great guy. He shouldn’t be so self-deprecating in his presentation because he had great information and it was an interesting topic. Parsing libraries are an area where Python has an excess of riches, and it can be difficult to decide what to use. Wilson made his choice and is happy with it, and makes a pretty convincing case for choosing PyParsing. It would be interesting to see projects such as reStructured Text, PyMarkdown, and PyTextile all built on top of the same basic parsing engine. Next time I have a file type to parse I will give PyParsing a try, based on this Wilson’s presentation.

After lunch, James Thiele gave a talk on embedding domain specific languages in Python, mainly revolving around the hooks Python gives you for importing libraries. By using the import hooks you can import code as Python objects which is not Python code. This is pretty cool, especially when coupled with the previous talk on Parsing.

There was a panel discusson on Little Languages, which both Wilson and James were on, but by now fatigue and distraction were taking their toll and I wasn’t a very good audience.

After lunch there was a presentation by Leonardo Almeida on Python and Zope in Brazil, which was basically that they are both widely used, in both business and government, but companies that use them don’t want to talk about it because they regard Python as their secret weapon.

David Ostrowski gave a talk on teaching with Python in graduate computer science classes, but I didn’t really enjoy the presentation. I was too tired and his points about Python were too familiar. I didn’t hear anything new, but it all appeared to be new to him. More power to him, I guess.

There were some good lightning talks at the end of the conference, including Brian Quinlan showing a hack he’d whipped up after the earlier talk on importing domain specific languages. He showed how to use the import hooks and the csv module to load comma separated value files as native python datatypes.

To close the conference, Ian Caven gave a great show about how he and a partner built up a successful business using Python (and OS X). They restore movies for DVD release and they use hundreds of Macs running in parallel, with all the processing managed by Python. It’s a great story and Ian is a great presenter, so that was a high note to end the conference on.

Looking forward to next time, for sure. Thanks to all the organizers!

[Update: Thanks to Blake Winton for pointing out that the project page link to the Pastels download was broken, fixed now. Also added a link to the project page.]

Pastels is an example project for creating an OS X screensaver in Python using PyObjC. By extension it could be used as an example for building nearly any plugin or bundle for OS X. It started when I had an idea for drawing a simple squiggle, over and over, while cycling the colours and moving the squiggle around. I was very pleased with how it turned out.

Project page: http://livingcode.org/project/pastels/

It’s also my first attempt at hosting an open-source project at Google with their new hosting program. If it works out well I will add more of my projects there, which will save me trying to set up and configure Subversion on Dreamhost for public access (probably not difficult, but one more thing I don’t have to do means more time for writing example code and tutorials).

I’m working on the tutorial text to go along with this project, so ask any questions you have and I’ll try to get to them in the tutorial.

If you are seeing this on my site (as opposed to the Atom feed), there are some changes I’m making to the site that I’d like to point out. I’ve added pages for projects and mini-projects which use the same stylesheet and includes as the rest of the site. I know the stylesheet is uglyless than completely attractive right now–the first thing was to get everything factored and consistent, then to make it pretty. The projects page only has one item on it (Pastels), but that should be changing now that I have the infrastructure set up the way I want it. Nearly all the projects I mentioned in my presentation at the Vancouver Python Workshop will get their own pages soon. More about that in my next post.

My latest article for David Mertz’s column XML Matters is up at IBM developerWorks: Lighter than microformats: Picoformats Ajax without X, Microformats without angle brackets went live a couple of days ago. It isn’t so much about XML as how to avoid XML. My feelings towards XML are that it is useful and good, but overused and not a panacea. By providing some alternatives, maybe some of the backlash against the “XML everywhere for everything” meme can be averted.

I’ve been meaning to post about the article, but I keep getting caught up preparing my presentation for the Vancouver Python Workshop on Saturday (the workshop starts Friday August 3rd and goes through Sunday August 5th). My talk this year is on using [PyObjC] to create applications and plugins for OS X using Python. I’ll get the slides up after, as soon as I can. I’m also planning on doing a shorter version of this talk at Bar Camp Vancouver which is 6 pm Friday, August 25 to 6 pm Saturday, August 26.

And I should have mentioned the Google talk at the Vancouver High Performance Computing User Group before it happened on July 27th. Narayanan ‘Shiva’ Shivakumar came up from their Seattle office to present mostly old information from their published papers such as The Google File System, MapReduce, and BigTable (video). The talk over beers after was fun, and it was good to see my friend Mark and find out he has a blog, even if it’s over my head much of the time.

Well, that’s my update dump. More stuff on actually using PyObjC coming Real Soon Now.

I noticed that jwz is trying to take a screenshot in Cocoa and having trouble. I’m happy to see that he’s porting his awesome collection of screensavers to OS X, that’s great news. As for taking screen shots, I’m amazed it is as hard as it seems to be–heck even the new Nokia Series 60 give you the ability to take screeenshots from Python now. In any case, here is a method that works for me under PyObjC. It assumes it is part of a Cocoa object and that you’ve done a from AppKit import * already. Since I can’t comment on jwz’s blog (whether it’s because I don’t use LiveJournal or because I do use Safari, I don’t know), I’ll post it here instead.

def screenShot(self):
    rect = NSScreen.mainScreen().frame()
    image = NSImage.alloc().initWithSize_((rect.size.width, rect.size.height))
    window = NSWindow.alloc().initWithContentRect_styleMask_backing_defer_(
        rect,
        NSBorderlessWindowMask,
        NSBackingStoreNonretained,
        False)
    view = NSView.alloc().initWithFrame_(rect)
    window.setLevel_(NSScreenSaverWindowLevel + 100)
    window.setHasShadow_(False)
    window.setAlphaValue_(0.0)
    window.setContentView_(view)
    window.orderFront_(self)
    view.lockFocus()
    screenRep= NSBitmapImageRep.alloc().initWithFocusedViewRect_(rect)
    image.addRepresentation_(screenRep)
    view.unlockFocus()
    window.orderOut_(self)
    window.close()
    return image

I cribbed this several months ago from some example Cocoa code, but forgot to make a note of where I got it. If anyone recognizes this pattern, please let me know so I can attribute it.

[Update 2006-03-10]

Nils Soffer pointed out:

A simpler solution:

try:

    screenshot = 'screenshort.pdf'

    os.system('screencapture -i %s' % screenshot)

    image = NSImage.alloc().initWithContentsOfFile_(screenshot)

finally:

    os.remove(screenshot)

:-)

Which reminds me, you can also use the command-line screencapture -c to go to the clipboard instead of a file.  This might be faster, but I haven’t tested it yet.  I still think there should be a Cocoa method to grab the underlying framebuffer of the screen. Besides the -c flag to send the image to the clipboard there is also a -C flag to capture the cursor as well.

[Update 2008-01-22]

Digging through old mail as I move this entry from my custom blog setup to Wordpress, I found where I got this code from originally. It’s from the Irate Scotsman’s Screen Sharing code.  Thanks, Matt!

Yes, I’ve been quiet for awhile. No, I’m not going to apologize, and I wish more bloggers would stop apologizing when they take time off. One of the great things about Atom/RSS feeds is that I can keep up with blogs that are posted to infrequently, which includes some of my favorites. Don’t feel like you need to post all the time–we’ve all got plenty of other things to read!

My quiet time is going to continue for a bit longer, but while I won’t apologize, I will at least explain. Here’s what I’m doing instead with the couple of hours I have between putting the kids to bed and going to bed myself.

• Writing the OS X version of the file uploader for The Conversation Network. At some point this will be made public, and the idea is to open source it. I’ll be sure to point that out when it happens. It’s been really great to have this opportunity to work with Doug Kaye and the rest of the gang from ITConversations, after being an admirer (and consumer) of their work for some time.
• Attended the Northern Voice and Moose Camp conference, where I was fortunate enough to co-moderate a session on community and blogs with Nancy White
• Writing my own weblog software. Blogger has a better interface than manilasites, but that’s not saying much. I’m also trying to port my old content from manilasites, plus my pre-blog-era work, plus my paper journal. All of this will be hosted at livingcode.org in the near future.
• Writing more articles for IBM developerWorks, I hope to have more to say about that Real Soon Now
• Generally organizing the livingcode site better, getting projects their own pages, putting code into SVN. Trying to use Sourceforge was a huge failure, their interface is just too crufty and they still don’t support Subversion. But Dreamhost (where livingcode.org is hosted) does support Subversion now, so I’m going to be moving all my public code over there.
• I wrote a screensaver using PyObjC which I’m hoping to get included in their distribution as an example, but I need to do some refactoring first (in the time leftover from other projects). I want to write that up too, it was pretty interesting to work on.
• I periodically take a stab at porting VPython to the Aqua environment. I have some ideas for this (some of them probably heretical to the VPython folks), but need time to work on them. Notice a pattern emerging?
• Porting Apple’s Sketch demo application from ObjectiveC to PyObjC.
• Several of these things are just precursors to DrawingBoard, my animation program for kids. I really, really want to be working on that, but need to get some of the smaller projects finished and out of my head so I can concentrate.
• Exploring programming environments for my kids. My nine-year-old daughter and I will try competing in the PyWeek game challenge later this month.
• I’m sure I’ve forgotten several significant things.

More news as it happens.