On May 27, 2010, at 11:38 AM, Sam Ruby wrote:
Well-supported arrays of structs (as schemas) might be a satisfactory
compromise. Consensus emerging around that solution.
Structs in ECMA-334 are value types, and consist of members that
also are value types. Would structs in future revisions of ECMA-262
share these characteristics?
Is it fair to assume that there would end up being a more richer set
of primitives to select from when composing a struct than simply
"object", "boolean", "number", "string" and the like? Again,
ECMA-334 defines the following:
http://en.csharp-online.net/ECMA-334:_11.1.5_Integral_types
Would something similar be envisioned for ECMA-262?
No, we did not envision adding more primitive types, type annotations,
conversion rules, and first-class struct declarations.
Something more like
const TA =
Array.newTypedArray(fixed_length,
Object.newStructType({x:"u32", y:"u32",
z:"u32",
r:"u8", g:"u8", b:"u8",
a:"u8"}));
let a = new TA(...);
... a[i].x ...
Khronos would like to continue developing their API as WebGL host
objects in the meantime. This may lead to forking of APIs in the
developers' minds. The possible danger is failure to reuse common
abstractions.
Need a champion. Waldemar offered to work with Khronos to drive a
proposal.
Dave, Vlad, and Andreas (Vlad is on the WebGL working group and has
implemented WebGL typed arrays in TraceMonkey) are interested in
collaborating too.
If structs are anything like value types, then I am interested in
participating. I'm particularly interested in working through the
details of how arithmetic of integer like quantities would work.
The struct-array idea for WebGL avoids the typed array aliasing
design, and consequent byte-order leakage. But we are not envisioning
new operator overloading or literal syntax. At most a[i].x would be
optimized to a very fast, packed member read or write, after scaling i
and adding the offset of x. Any read would use ES's number type, I
believe.
There's an issue with float32 -- IIRC it does not project into float64
(AKA double). All the other types (uint32, what I schematically named
"u32" above, etc.) do.
/be
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