I posted a new stawman that describes what I think should is that most minimal
support that we must provide for "full unicode" in ES.next:
http://wiki.ecmascript.org/doku.php?id=strawman:full_unicode_source_code
I'm not suggesting that we must stop at this level of support, but I think not
doing at least what is describe in this proposal would would be mistake.
Thoughts?
Allen
On Feb 28, 2012, at 3:49 AM, Brendan Eich wrote:
> Wes Garland wrote:
>> If four-byte escapes are statically rejected in BRS-on, we have a problem --
>> we should be able to use old code that runs in either mode unchanged when
>> said code only uses characters in the BMP.
>
> We've been over this and I conceded to Allen that "four-byte escapes" (I'll
> use \uXXXX to be clear from now on) must work as today with BRS-on. Otherwise
> we make it hard to impossible to migrate code that knows what it is doing
> with 16-bit code units that round-trip properly.
>
>> Accepting both 4 and 6 byte escapes is a problem, though -- what is
>> "\u123456".length? 1 or 3?
>
> This is not a problem. We want .length to distribute across concatenation, so
> 3 is the only answer and in particular ("\u1234" + "\u5678").length === 2
> irrespective of BRS.
>
>> If we accept "\u1234" in BRS-on as a string with length 5 -- as we do today
>> in ES5 with "\u123".length===4 -- we give developers a way to feature-test
>> and conditionally execute code, allowing libraries to run with BRS-on and
>> BRS-off.
>
> Feature-testing should be done using a more explicit test. API TBD, but I
> don't think breaking "\uXXXX" with BRS on is a good idea.
>
> I agree with you that Roozbeh is hardly used, so it can take the hit of
> having to feature-test the BRS. The much more common case today is JS code
> that blithely ignores non-BMP characters that make it into strings as pairs,
> treating them blindly as two "characters" (ugh; must purge that "c-word"
> abusage from the spec).
>
> /be
>
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