On Dec 8, 2009, at 12:52 PM, Mike Samuel wrote:
2009/12/8 Brendan Eich <[email protected]>:
On Dec 8, 2009, at 11:51 AM, Erik Corry wrote:
for (let i in arraylike) {
i |= 0;
If this pattern catches on then we could optimize for it without
changing the language.
Yeah, but some day there will be only "new" versions in which i is
numeric
for arraylikes and that becomes pointless. On that fine day
programmers can
stop writing the ugly extra statement. That's worth something too,
even as a
new loop construct "could be nicer".
Do we want nicer with high migration tax and greater total language
complexity (new loop construct), or nicer with lower tax (reformed
for-in
under new opt-in version), or not-so-nice with perpetual type-fixup
kludge
Well, we have "use strict," and then this would give us "use integer,"
so all that leaves would be an excuse to shoehorn "use vmsish" into
the language :)
I remember VMS. Not as good as TOPS-20 :-P.
Seriously, opt-in versioning will not be via too many "use mumble"
pragmas, rather whole-edition selection a la RFC 4329. The "use
strict" idea is good but we don't want endless feature knobs (we =
everyone, TC39, developers, implementors).
More, while in-language version selection may yet happen, I don't see
how it helps with new syntax. You'll get syntax errors from old
browsers without any way to handle them (no fallback or alt content
for <script>).
More controllable (for authors) is something like the sketch here:
http://wiki.ecmascript.org/doku.php?id=proposals:versioning
linked from
http://wiki.ecmascript.org/doku.php?id=strawman:versioning
Your thoughts and edits are welcome on this last page.
/be
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