Sweet! Thanks for the info.
Kevin N.
Nicolas Cannasse wrote:
Here are some things I've been wondering about Actionscript 3.0s
compiler and runtime engines:
I'm assuming AS 3.0 compiles to a bytecode. What kind of bytecode
does it compile to? Is it more like Java/.NET CLR, or more like
Mozilla's Spidermonkey compiler?
I don't know about SpiderMonkey, but AS3 bytecode is similar to Java
one. It's actually more complicated since there is several way to
access the properties (using prototype, traits or "slots").
Does the compiled code get recompiled during runtime to machine code
(like a JIT compiler) or does it get interpreted?
Some Adobe presentation on the subjet was saying that all the code get
JIT'ed, except the $iinit and $cinit functions which are the one
defining the classes and initializing their static variables.
Also, how does the compiler deal with typing? Statically typed,
compiled languages usually have the type set in stone at compile time
whereas dynamically typed, interpreted languages like javascript and
php can do type coercion at runtime on the fly. Which one does the
Actionscript 3.0 runtime do? Does it do both depending on whether the
type is static or dynamic?
The complete class structure with type is stored into the Flash9 SWF.
Then local (per-function) type-inference is performed to check the
types coherency. There is some bytecode options that perform
type-casting. For instance everytime a value is stored into an untyped
variable, the opcode 0x82 is "forgetting" about the original value type.
This makes things actually pretty difficult for other languages with
different type system to be compiled to Flash9 bytecode, but I could
succeed in doing it for haXe (http://haxe.org).
I started documenting the Flash9 file format on
http://osflash.org/flash9, you can start reading there, but only the
haXe swf library sources are containing the complete specification :
http://cvs.motion-twin.com/horde/chora/browse.php?rt=ocaml&f=swflib
Nicolas
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