> On Sep 4, 2013, at 3:05 AM, Andreas Rossberg <[email protected]> wrote: > >> On 4 September 2013 10:23, Dmitry Lomov <[email protected]> wrote: >> I think we should consider fixed-length ArrayTypes in this discussion. They >> can be parts of structs. >> Consider >> var A = new ArrayType(uint8, 10); >> var S = new Struct({a : A}); >> var a = new A(); >> var s = new S(); >> a[0] = 10; >> a.foo = "foo"; >> s.a = a; >> Assignment to a struct field is a copy, essentially. Of course, s.a[0] is >> now 10. But does s.a.foo exist? In the current semantics, there is no place >> to store it, because a field 'a' of struct 'S' is just a storage designator >> - there is no "place" in struct s to store the expando properties of fields >> and fields of fields and fields of fields of fields.... >> >> Therefore in current semantics fixed-length ArrayTypes, just like >> StructTypes, are either non-expandable, or have to lose their expanded >> properties on assignments - big surprise for the user! >> >> Now of course variable-sized ArrayTypes do not suffer from this issue, but >> one could argue for consistency with fixed-sized ArrayTypes. > > I was about to make the same point. :) > > As part of binary data, typed arrays are implicitly constructed "on > the fly" as views on a backing store. Any notion of identity -- which > is the prerequisite for state -- is not particularly meaningful in > this setting.
Are you proposing changing how == and === work for typed arrays? If not then this whole argument is moot. > Also, it is preferable to make them as lightweight as > possible. See my previous mail. You gain zero space and zero performance from making typed arrays non extensible. > > As for other typed arrays, the difference is subtle, and I'd rather go > for consistency. > > /Andreas > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
