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March 31, 2008
Code Coverage in AS3, ECMAScript 4, and More
Here's a grab-bag of links, with the first one being the most well-known on the Flex blogs. I still wanted to link to Joe Berkovitz's post on code coverage in AS3, because I'm excited to see this getting done (and someone making some interesting changes to the compiler). But I don't have much to add to the discussion. Go read Joe's blog for all the good details.
A new draft of ECMAScript 4 is out, and the mailing list is getting filled with interesting posts on the final proposals. Check out Insurrection, a thread which contains a thoughtful critique of ECMAScript 4.
I don't see anything interesting happening yet in the commit logs for Flex, but they're fun to watch again.
Nearly as much fun as the commit logs is seeing random new developments in all corners of the Flex world. I don't keep up with a good fraction of the blog posts on Flex anymore, so I'm sure I'm missing a lot of things like an Emacs mode for Flex.
The Boston Flex User Group
The Boston Flex User Group starts a week from Tuesday at the Adobe office in Newton. Find out more at the it's-just-missing-drop-shadows homepage.
There's already a lot of other groups that touch on Flex already- Boston Flash Platform User Group, Boston Design Patterns Group, Adobe Boston User Group, Flex App Incubator Group, and Boston ColdFusion Group. Until I typed them out, I had forgotten how many groups there are. But it'll be excellent to have one that's just focused on Flex, and I know there'll be a better chance for a lot of people to talk with the Flex team, given the location.
March 14, 2008
Good-bye Mr. Gobbles
I'll miss seeing you peck at the car tires in Kendall Square.
(Sure, I could be writing something about the Flex compiler, or the recent YouTube changes, or other useful things. But it's just Mr. Gobbles today.)
Posted by Brian at 12:42 PMMarch 10, 2008
Decompiling AS3 and Random Compiler Thoughts
When the Flex compiler was open sourced, I wanted to get my hands dirty and make a change or two myself. In the first week I dug into the source and looked to make a change to decompile (or rather disassemble) AS3. Of course, after I'd dug into things I realized that Adobe has already done this. And someone created an AIR app. And a commercial decompiler. This is what I get when I don't keep up with my blog reading.
While I didn't end up making any changes, I'm going to give a partial explanation of this code.
The entry-point for the AS3 disassembler is flash.swf.tools.SwfxPrinter. If you take a look at this class, you'll see a method for each tag that needs to be handled, with each method taking in a Tag class. These correspond to the different tags in the SWF format. The one that is of interest for AS3 decompiling is DoABC. (To be pedantic, we actually use the DoABC2 version of this tag, which is a bit confusing, but the original DoABC tag was never released.) This is the tag which contains ABC, the compiled AS3 that the Flash Player runs. Going back to SwfxPrinter, you'll see the DoABC method takes this bytecode and through the magic of AbcPrinter prints out all the operations.
I assumed that the SwfxPrinter would work by parsing Nodes and not directly work from the ABC. As explained above, the ABC is what's actually in the SWF, and it's contained within a DoABC tag. The Nodes are an abstraction of the bytecode that the AS3 compiler uses. It's what is generated within the compiler when you first compile an application, but there's also a way to get Nodes from a finished compilation. You can see this in action within the SwfxPrinter.doABC() tag. Within the showActions code, you can see how the ABC is turned into the top-level Node, a ProgramNode, which then can be printed out via the PrettyPrinter. I tried enabling this code myself, and it doesn't work very well. There's a lot of missing pieces to the output, so apparently everyone should keep using the existing path of parsing the ABC bytecode for printing.
That's a little more insight into the class used for AS3 disassembling, but it doesn't even touch the real work in decoding the ABC format, TagHandlers, etc. There's always plenty more to learn in the compiler, and hopefully I'll be able to blog more in the future about the parts that I know.
We were talking about the compiler and ideas for improvements at the last Boston Flash Design Patterns Group, where we stopped talking about design patterns for a week and instead talked about the Flex compiler and the need for more comments. People wanted to know the easiest places to make some changes, and I couldn't come up with much. There's some jumping-off points in flex2.tools.Compiler or flex2.tools.Compc. Changing a Transcoder could be interesting, or adding one to the list in flex2.tools.API.getTranscoders(). If you'd like to try something for fun, you could always alter Grammar.jj to change the core of MXML. Daniel Rinehart is looking at making a change to the compiler, and it's going to be interesting to see all the changes coming in from around the community.
Update: See Random Compiler Thoughts, Part II for more info on the compiler.
March 9, 2008
Nevermind This Post
I've been looking again at Ted's post on Extending Adobe Flash Player and Adobe AIR with C and C++ via ActionScript 3 as well as the video on Quake on the Flash player. I had a long post written, giving my guesses on what's happening. And then I did one last search and realized I missed a great interview by Ryan Stewart, where most of my postulations have real answers. So nevermind.
March 3, 2008
The Brightcove Office Invasion
It doesn't have the Golden Girls like the Flex behind the scenes videos, but Boston.com came by the Brightcove office a few weeks ago for a video about development hell and Paris Hilton.
In other Brightcove news, check out a new use of Aftermix, with pages to create and view mashups on snow.com. It's the first off-site use of the application.
I haven't been working on Aftermix lately, but there's a lot of other interesting Flex work going on here... just nothing I can blog about yet.
Posted by Brian at 8:05 AM
