On Sep 29, 2011, at 3:20 PM, Russell Leggett wrote:
> On Wed, Sep 28, 2011 at 10:40 PM, Oliver Hunt <[email protected]> wrote:
>
> Given our apparent desire to have a declarative syntax i don't see why
> something akin to:
>
> class Foo {
> var bar; // default value -> undefined
> var wibble = 5; // initialised fields desugar to statements at the head of
> the constructor
> const wiffle; // read barrier on uninitialised
>
> function someMethod(..) {
> this.bar = foo; // could have a short hand for this.property
> }
>
> constructor (bar, wibble) {
> // extra typing due to the removal of horrible punning
> // but "public bar = bar" or whatever that syntax was is longer
> // than this.bar
> this.bar = bar;
> this.wibble = wibble;
> }
> }
>
> function's get shoved on to the prototype chain, and fields go on the
> instance, inheritance follows reasonably sensibly from that. Remove the
> declarative field definitions and you have essentially got python's class
> model, which seems to be well accepted by a wide array of people, otherwise
> the question becomes one of how much you want to lock down the resultant
> object shape.
>
> --Oliver
>
>
> Hi, just a voice from the peanut gallery - of the proposals going on right
> now, I really like this proposal a lot. Perhaps it is just my experience with
> Java, but this feels like an intuitive class syntax that also stays feeling
> like JavaScript. I like that it doesn't introduce a new keyword "public"
> which I especially didn't like because there was no "private" keyword.
This syntax is awfully familiar from original-JS2/ES4 (Waldemar's 1999-2003
effort) and the 2006-2008-era ES4.
There are some on the committee who object to 'var' in particular; others
object to using scoped binding forms to define properties in (default mutable)
objects. We can go around this block again, though.
> In regards to private fields/methods in classes, I did also have a thought
> that perhaps you could use proxies to provide a peephole view of a class
> instance.
Proxies are too heavyweight. We have private name objects:
http://wiki.ecmascript.org/doku.php?id=harmony:private_name_objects
which can be implemented very cheaply, and our current consensus for private in
classes is that you would bind module- or block-scoped consts to private names,
one per class-private instance variable, and then use them via this[priv] =
initialValue, Object.create, Object.defineProperty, etc.
/be
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