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Re: [Public WebGL] WebGL, typed arrays, Web IDL, ECMAScript



Kenneth Russell:
> Strictly speaking, the Typed Array specification would only need
> unsigned byte introduced since octet is already in the spec, but it
> would be convenient if byte could be introduced as well for symmetry.
> We found that all of the other concepts, like omittable getters and
> setters, were already present in Web IDL.

Yeah, perhaps I’ll rename octet to unsigned byte.

> For WebGL in general, one of the recent sticking points has been the
> different handling of wrong numbers of arguments to function calls
> between Web IDL and ECMAScript. In pure ECMAScript, if too few
> arguments are passed to a function, "undefined" is passed for the
> remaining arguments. In some browsers' scripting engines an exception
> is thrown when a function on a host object is called with too few
> arguments; in some, the ECMAScript behavior is taken. I think the Web
> IDL spec is a little ambiguous on this topic, in particular for
> non-overloaded functions; correct me if I'm wrong.

I think for non-overloaded functions (as well as overloaded ones with
too few arguments) it is defined to throw a TypeError, rather than
assume undefined.  The overload resolution algorithm
http://dev.w3.org/2006/webapi/WebIDL/#dfn-overload-resolution-algorithm
will start off with the single operation with a certain argument type
list length, and then step 2 will result in the set becoming empty if
the number of arguments passed wasn’t exactly that number.

It’s still an open issue whether that, or assuming undefined, is the
behaviour we want to end up with.

Overloading in Web IDL is well defined, but kind of a mess at the
moment, and subject to change.

> Note also that we are thinking of adding support for read-only Typed
> Array views to better handle the use case of XMLHttpRequest, which
> will involve some refactoring of the type hierarchy but not change it
> substantially. We have also been thinking about adding a couple of
> methods and postMessage() semantics to help send data to web workers
> and back.

OK, so in your view typed arrays are the way forward for array types in
Web APIs in general?

-- 
Cameron McCormack ≝ http://mcc.id.au/
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