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Groups > comp.std.c > #6217

Re: Add @ to basic character set?

From Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups comp.std.c
Subject Re: Add @ to basic character set?
Date 2021-03-11 15:40 -0800
Organization None to speak of
Message-ID <8735x1i7ir.fsf@nosuchdomain.example.com> (permalink)
References <rqfeip$lrr$1@solani.org> <s2e3av$429$1@solani.org>

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Philipp Klaus Krause <pkk@spth.de> writes:
> Am 05.12.20 um 08:58 schrieb Philipp Klaus Krause:
>> I wonder if it would make sense to add @ to the basic character set.
>> Virtually everyone is using it in comments and strings already anyway
>> (for email addresses), and I don't see anything preventing
>> implementations from supporting it, as it is available in both ASCII and
>> common EBCDIC code pages:
>> 
>> http://www.colecovision.eu/stuff/proposal-basic-@.html
>
> After some discussion and thought, IMO, the way forward is to add @ to
> the source and execution character sets, but not the basic source
> character set:
>
> http://www.colecovision.eu/stuff/proposal-@.html
>
> Do you think this proposal makes sense as is? If yes, do you have a
> preference for adding them as single bytes vs. not specifying if they
> are single bytes? If yes, why?

It's not *necesary*, but I wouldn't object to it.

If this change is going to be made, I'd advocate also adding $
(mentioned in the proposal) and ` (not mentioned).  None of @,
$, and ` are required for any C tokens, but many implementations
allow $ in identifiers.  @, $, and ` are the only ASCII characters
that are not part of the C basic character sets.  All are commonly
used in character constants and string literals.  (`, backtick,
is used in Markdown and some other languages.)

The *basic* characters are those that are required for all
implementations.  The set of *extended* characters is
implementation-defined, and may be empty.  The @, $, and ` characters
are extended characters in most or all current implementations. If @, $,
and ` are going to be required, I think they should be in the basic
character set.  That's the point of the distinction between basic and
extended characters.

Both ASCII and the EBCDIC code pages that support them represent
all these characters in one byte.  Their representations should be
required to fit in a byte, since that already applies to all the
other basic characters; allowing them to be multi-byte wouldn't
help portability and would add complexity.

The vast majority of implementations already conform to this proposal,
except perhaps for a minor documentation update.

The only reasons I can think of *not* to make this change are (a) *any*
change to the standard needs to justify the work needed to make the
change and this one isn't really necessary, and (b) apparently some
EBCDIC codepages don't support all these characters.  If the latter
affects any actual implementations, the could pick some other printable
characters to stand in (similar things have been done in the past for
old ASCII variants).

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips Healthcare
void Void(void) { Void(); } /* The recursive call of the void */

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Thread

Add @ to basic character set? Philipp Klaus Krause <pkk@spth.de> - 2020-12-05 08:58 +0100
  Re: Add @ to basic character set? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-12-05 10:53 -0500
    Re: Add @ to basic character set? David Brown <david.brown@hesbynett.no> - 2020-12-05 17:15 +0100
      Re: Add @ to basic character set? Philipp Klaus Krause <pkk@spth.de> - 2020-12-05 20:55 +0100
    Re: Add @ to basic character set? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-05 14:17 -0800
      Re: Add @ to basic character set? Francis Glassborow <francis.glassborow@btinternet.com> - 2020-12-06 12:25 +0000
        Re: Add @ to basic character set? David Brown <david.brown@hesbynett.no> - 2020-12-06 13:47 +0100
          Re: Add @ to basic character set? Richard Damon <Richard@Damon-Family.org> - 2020-12-06 08:42 -0500
            Re: Add @ to basic character set? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-06 14:07 -0800
              Re: Add @ to basic character set? Richard Damon <Richard@Damon-Family.org> - 2020-12-06 17:44 -0500
                Re: Add @ to basic character set? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-06 15:49 -0800
                Re: Add @ to basic character set? Philipp Klaus Krause <pkk@spth.de> - 2020-12-07 09:31 +0100
                Re: Add @ to basic character set? Richard Damon <Richard@Damon-Family.org> - 2020-12-07 07:24 -0500
                Re: Add @ to basic character set? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-07 12:16 -0800
                Re: Add @ to basic character set? Richard Damon <Richard@Damon-Family.org> - 2020-12-07 15:51 -0500
                Re: Add @ to basic character set? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-07 13:10 -0800
                Re: Add @ to basic character set? Andreas Schwab <schwab@linux-m68k.org> - 2020-12-07 23:52 +0100
                Re: Add @ to basic character set? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-07 15:27 -0800
                Re: Add @ to basic character set? Richard Damon <Richard@Damon-Family.org> - 2020-12-07 18:54 -0500
                Re: Add @ to basic character set? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-07 16:10 -0800
                Re: Add @ to basic character set? Richard Damon <Richard@Damon-Family.org> - 2020-12-07 18:31 -0500
                Re: Add @ to basic character set? Andreas Schwab <schwab@linux-m68k.org> - 2020-12-07 23:08 +0100
              Re: Add @ to basic character set? Philipp Klaus Krause <pkk@spth.de> - 2020-12-07 09:30 +0100
      Re: Add @ to basic character set? Philipp Klaus Krause <pkk@spth.de> - 2020-12-07 09:17 +0100
  Re: Add @ to basic character set? Thomas David Rivers <rivers@dignus.com> - 2020-12-06 16:11 -0500
    Re: Add @ to basic character set? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-12-07 12:19 -0800
      Re: Add @ to basic character set? Thomas David Rivers <rivers@dignus.com> - 2020-12-07 17:02 -0500
  Re: Add @ to basic character set? Philipp Klaus Krause <pkk@spth.de> - 2021-03-11 22:50 +0100
    Re: Add @ to basic character set? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-03-11 15:40 -0800
      Re: Add @ to basic character set? Philipp Klaus Krause <pkk@spth.de> - 2021-03-12 15:25 +0100
    Re: Add @ to basic character set? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-07-10 08:46 -0700

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