Kevin Reid's blog

I'm not making progress as fast as I would like; mostly due to assorted distractions rather than Doing The Work.

That said, I've gotten both ends of serialization implemented, at least for non-circular cases: the deJSONTreeKit and deSubgraphKit have both builder and recognizer implementations. (For a terminology introduction, see the serialization paper.)

Next up is the surgeon (high-level serialization interface), and designing uncallers suitable for JavaScript. I definitely need to increase my rate of progress to get this done on schedule.

I have begun the work on my GSoC project, Caja-CapTP.

I am currently working on improving E-on-JavaScript in order to be able to use its Updoc facility as the test framework for the Caja-CapTP code.

(If you don't know, Updoc is a test system which works by rerunning a recorded or made-up interactive session and confirming that the output is the same as before. The advantage of this system is that you can write test cases very simply as sequential code without gobs of assertFoo() for every particular attribute you think of testing.)

You can see my commits to EoJS at CIA.vc.

I am also learning more about exactly how Cajita works in areas such as library loading; the documentation in this area needs improvement, which I am going to work on myself and/or ask the Caja developers to clarify.

So. In JavaScript, an “object” is a set of “properties”: associations from strings to values. A method is just a property whose value is a function. Functions are called like “foo()”, properties are accessed like “bar.foo”, and methods are called like “bar.foo()”. Looks straightforward enough, right?

Now, how does a method access the state of its object? Without inheritance, you could just have the method functions of a given object all close over some variables; but JavaScript does have prototype inheritance, so the necessary access is provided by binding the variable “this”, in the method body, to the object the method was invoked on.

And when does this happen? When you use the method call syntax. bar.foo() is not the same as

var m = bar.foo;
m();

(It is the same as m.call(bar) — call is a method on function objects which invokes them with this bound — but that's beside the point.)

So, the syntax is non-compositional.

Not only that, but it is enthusiastically so: bar.foo() is the same as (bar.foo)() — the parentheses do not break up the method call construct!