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Re: Agenda for the 2022-10-12 SG16 telecon​

From: Corentin Jabot <corentinjabot_at_[hidden]>
Date: Sat, 8 Oct 2022 11:38:35 +0200
At the risk of spoiling

E.2.1 and E.5 (https://eel.is/c++draft/uaxid) are a repeat of [lex.name]
Everything else in [uaxid] is a list of things C++ does not conform to,
mostly because none of these things would apply one way or another.

A note (or other form of mention) in [lex.name] stating "C++ conforms to
UAX31 by meeting the requirements R1 'Default Identifiers' and R4
'Equivalent Normalized Identifiers'. Other requirements do not apply."
would carry the same meaning.

Beside the maintenance burden of an annex that is not information dense,
and the fact that the conformance information is more useful to have in [
lex.name], as C++ adds Unicode support (for example unicode regex), having
an annex per UAX/TR does not seem practical or desirable.

Note that I'm not opposed to mentioning the conformance information, quite
the opposite, it's very useful information.
I'm just saying an annex which is by large a list of requirements not met
is less useful than having the information available where it's relevant,
in a more concise form.

On Sat, Oct 8, 2022 at 1:31 AM Steve Downey <sdowney_at_[hidden]> wrote:

> If there are other comments about Annex E we'll have to do work to merge
> them in any case. Unless it's to drop Annex E entirely, which I would be
> against.
> On Fri, Oct 7, 2022 at 7:29 PM Steve Downey <sdowney_at_[hidden]> wrote:
>> US-64 was supposed to have a matching paper, but it looks like it got
>> folded inline. In any case https://isocpp.org/files/papers/P2653R0.pdf
>> UAX #31 describes how languages that use or interpret patterns of
>> characters such as regular expressions or number formatscomputer
>> languages, may describe that syntax with Unicode properties.
>> C++ does not do this as part of the language, deferring to library
>> components for such usage of patterns. This requirement does not apply to
>> C++.
>> C++ does not use the methods or properties in UAX #31 to do this. It
>> instead uses the whitespace and syntax characters defined in [lex] to
>> describe the white space characters and the basic source characters used to
>> define syntactic elements other than identifiers.
>> Wordsmithing more than welcome.
>> On Thu, Oct 6, 2022 at 6:19 PM Corentin Jabot via SG16 <
>> sg16_at_[hidden]> wrote:
>>> I would prefer to wait for all nb comments to be filled in. In
>>> particular, US-38 and US-64 may end up conflicting or overlapping with
>>> other NB comments.
>>> Thanks,
>>> Corentin
>>> On Thu, Oct 6, 2022 at 11:59 PM Tom Honermann via SG16 <
>>> sg16_at_[hidden]> wrote:
>>>> SG16 will hold a telecon on Wednesday, October 12th, at 19:30 UTC (timezone
>>>> conversion
>>>> <https://www.timeanddate.com/worldclock/converter.html?iso=20221012T193000&p1=1440&p2=tz_pdt&p3=tz_mdt&p4=tz_cdt&p5=tz_edt&p6=tz_cest>
>>>> ).
>>>> The agenda is:
>>>> - A presentation by Michael Kuperstein regarding i18n and l10n and
>>>> existing practice in the industry.
>>>> - NB comment processing.
>>>> INCITS has made US NB comments available to its members. I reviewed the
>>>> list and identified the following as ones that I believe SG16 should
>>>> establish a position on. There are other comments that are related to
>>>> papers SG16 has previously discussed, but in those cases, I believe the
>>>> concerns raised do not require SG16 input.
>>>> Due to duplicated comments in the list of US comments, it is possible
>>>> that the comment identifiers below will change.
>>>> US-2: [defns.multibyte] <http://eel.is/c++draft/defns.multibyte>
>>>> The notion of an "execution character set" is no longer given
>>>> prominence in the Draft standard, aside from some notes about its
>>>> relationship to the concept as defined by C, and clarifying that certain
>>>> character encodings are unrelated to this character set. This makes it a
>>>> questionable choice for use in the definition of "multibyte character".
>>>> *Proposed change:*
>>>> Change the definition of "multibyte character" to use a character
>>>> encoding with a more definite specification given by the Standard.
>>>> US-38: [format.string.escaped]
>>>> <https://eel.is/c++draft/format.string.escaped>
>>>> The subject subclause describes how characters or strings are "escaped"
>>>> to be formatted more suitably "for debugging or for logging".
>>>> The actual suitability for debugging or for logging depends on the
>>>> needs of the application, and there is a conflict between formatting for
>>>> human readability of the textual content and formatting for clarity and
>>>> fidelity of encoding nuances. Indeed, for the latter, there can still be
>>>> (for stateful encodings) a conflict between formatting for human visual
>>>> inspection versus formatting for machine consumption of the output sequence
>>>> as a C++ string/character literal.
>>>> The current design introduces extensions to the API and to the format
>>>> string syntax that assume that there is one specific default that should be
>>>> chosen "for debugging or for logging". The reasoning behind the chosen
>>>> default and the extensibility of the current design does not appear to be
>>>> sufficiently explored.
>>>> Note 1:
>>>> An example, for Unicode encodings, of a choice between prioritizing
>>>> between human readability of the textual content and visual clarity of
>>>> encoding nuances is in the treatment of characters having Unicode property
>>>> Grapheme_Extend=Yes. The current design favors visual clarity of encoding
>>>> nuances by outputing such characters as escape sequences.
>>>> Note 2:
>>>> For stateful encodings, the lack of return to the initial shift state
>>>> at the end of the sequence cannot be represented using a C++
>>>> string/character literal unless if a prior shift sequence from the initial
>>>> shift state is rendered via escape sequence(s). It is not clear that
>>>> scanning forward is generally always an option (nor is it clear that doing
>>>> so is desirable).
>>>> *Proposed change:*
>>>> Narrow the purported scope and affirm the design choices of the default
>>>> behavior:
>>>> Modify "logging" to "technical logging" and spell out the priorities in
>>>> order in the description (this has the benefit of clearly communicating
>>>> intention and providing guidance for implementation choices).
>>>> 1. The output is intended to be a C++ string/character literal that
>>>> reproduces the encoded sequence. (This seems to be taken for granted and
>>>> not made explicit in the current draft.)
>>>> 2. Prefer visually distinguishing between different methods of
>>>> encoding "equivalent" textual content.
>>>> Make any adjustments necessary to the API or the format string syntax
>>>> associated with "escaped" strings to allow for future additions for
>>>> alternative escaping.
>>>> US-64: [uaxid.pattern] <https://eel.is/c++draft/uaxid.pattern>
>>>> The Unicode org has clarified that the pattern whitespace and pattern
>>>> syntax rules apply to the lexing and parsing of computer languages.
>>>> *Proposed change:*
>>>> Replace with "UAX#31 describes how formal languages such as computer
>>>> languages should describe and implement their use of whitespace and
>>>> syntactically significant characters during the processes of lexing and
>>>> parsing. C++ does not claim conformance with this requirement."
>>>> Tom.
>>>> --
>>>> SG16 mailing list
>>>> SG16_at_[hidden]
>>>> https://lists.isocpp.org/mailman/listinfo.cgi/sg16
>>> --
>>> SG16 mailing list
>>> SG16_at_[hidden]
>>> https://lists.isocpp.org/mailman/listinfo.cgi/sg16

Received on 2022-10-08 09:38:49