Pure Danger TechAlex Miller’s technical blog

1. Ricky Clarkson Jun 30 2008 / 1am

   When you do work up the nerve, I hope Sun has fixed the broken links that are the “Watch” and “MP3″ buttons. The PDF version works fine though.
2. Casper Bang Jun 30 2008 / 6am

   Everything worked fine for me, both the watch functionality and the MP3’s. Great talk!

   Your talk did make me wonder again why everyone screams DI and “singletons are bad”, when there’s a perfectly balanced middle ground of simply writing your singleton to an SPI. It basically achieves DI through the class path and works fine in a typical Ant/Maven based run/test scenario.

   Many developers (my colleagues and I anyway;) are favoring “back-to-basics” and are not particular keen on adding more frameworks to the already complex stacks and configurations we juggle every day.
3. Alex Jun 30 2008 / 7am

   @Ricky: Links worked fine for me last night and this morning as well.

   @Casper: Not sure what you mean by writing to an SPI? Do you mean the singleton is still obtained through static calls but there is a setter that can be used to install a well-defined singleton implementation? Or something else?
4. Casper Bang Jun 30 2008 / 8am

   @Alex: No I mean writing to an SPI (service provider pattern) rather than an API by using java.util.ServiceLoader (javax.imageio.spi.ServiceRegistry if on JRE1.4.2).

   It’s basically just another manifestation of “program to an interface”, the difference being that you can place the contract in one JAR and implementations in other and have Java discover/plug-in the implementation at run-time.

   I use it a lot to decouple dependencies between subsystems in a double-dispatch fashion as well as for singleton mock purposes. I am surprised this approach is not used more often, though I believe NetBeans/OpenIDE uses it (or variations of it) pervasively.
5. Alex Jun 30 2008 / 8am

   @Casper: Ah, gotcha. ServiceLoader fills the same “discovery” gap that OSGi does - the ability to know what classes implement an interface in your available classes. I don’t think ServiceLoader is well known or used yet.
6. David Karnok Jun 30 2008 / 10am

   A dozes slides between page 23-35 in the watch section have missing audio. How far is this region in the MP3?
7. Alex Jun 30 2008 / 11am

   If you’re referring to the section on Proxy in slides 28-35, then you won’t find audio because I skipped that section during the talk. I wasn’t sure how fast I was going to be speaking but suspected that the 8 minutes or so of that section might need to be skipped to pare it down and indeed that was necessary to hit the 50 minute time box. That’s why the No Fluff conference sessions are so much nicer at 90 minutes - you can really get into significantly more depth in a single session.
8. Stefan Schulz Jun 30 2008 / 1pm

   Thanks for that talk. Enjoyed it a lot.

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