On Dec 3, 2012, at 11:53 AM, Jussi Kalliokoski <[email protected]>
wrote:
> I was just reading through the binary data proposal [1] and I have a few
> comments / questions:
>
> First of all, how will this integrate with the Typed Arrays?
Typed Arrays will become a special case of binary data objects. In other words,
the binary data API generalizes typed arrays completely.
> Will a struct have an intrinsic ArrayBuffer?
Yes, but with some exceptions. We will be extending the API to allow fields of
type "object" (basically, pointers to JS objects) or the type "any" (basically,
any JS value whatsoever), but those types will not be allowed to expose their
ArrayBuffer.
> What about an ArrayType instance? If they do, how will it react to typeless
> properties? Are typeless properties allowed in the first place (IIRC there
> was a talk I watched where David Herman or someone else said that this might
> be)? Will you be able to extract structs out of an ArrayBuffer?
Same story: if you have the type "object" or the type "any" you can't get at
the underlying ArrayBuffer.
> What about strings? Looking through the binary data related proposals, there
> seems to be no good way of extracting strings from binary data. Should we
> have, for example StringType(DOMString encoding, uint length, boolean
> isPadded=false) for Structs? Or, should DataView have a method for extracting
> a string from it? What about storing one?
As Ken says, the WhatWG string encoding/decoding spec is the way to do that.
The important thing to recognize is that a string formats are just that --
encoding/decoding formats -- rather than "types." There isn't and won't be a
string type, or a UTF8 type, or anything like that in the API.
> Pointers. Now it's useful if a struct can contain an array of arbitrary size,
> but we don't have pointers. We can't let the struct be of arbitrary size
> either. What are the thoughts on this?
See above.
> Arrays inside structs. Are there plans for this? They're not absolutely
> necessary, but often quite handy anyway, for example:
>
> StructType({
> unique: uint32[4]
> })
That's definitely supported.
> Also, what's the plan with Typed Arrays anyway? Are we going to adopt them as
> a part of JS or leave it as an extension?
Fully adopted.
> Binary stuff is hard in a language like JavaScript, but I think that
> ultimately we'll get something workable, and would love to see more
> discussion around this!
I think binary data will be very nice in ES6, and I'm excited about where it's
headed. We've started implementation in SpiderMonkey and hopefully before too
long people will be able to start experimenting with it in nightly builds of
Firefox.
Thanks for your questions!
Dave
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