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| From | James Kuyper <jameskuyper@verizon.net> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Untyped Variables |
| Date | 2015-08-10 11:01 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <mqaea6$3qq$1@dont-email.me> (permalink) |
| References | (1 earlier) <55C61BBF.8090302@verizon.net> <ln37ztfte6.fsf@kst-u.example.com> <8eb33dc8-5c47-4b7b-a20e-584166a50d58@googlegroups.com> <55C69FFA.7050309@verizon.net> <ba0351fd-385d-4bc1-b947-380e83defb2b@googlegroups.com> |
On 08/09/2015 09:02 PM, David Kleinecke wrote:
> On Saturday, August 8, 2015 at 5:34:12 PM UTC-7, James Kuyper wrote:
>> On 08/08/2015 07:06 PM, David Kleinecke wrote:
>> ...
>>> I haven't been thinking of constraints as part of syntax. ...
>>
>> It would be more accurate to say that some constraints constrain the
>> syntax. For example (6.4.3p1):
>>
>>
>>> 1 universal-character-name:
>>> \u hex-quad
>>> \U hex-quad hex-quad
>>> hex-quad:
>>> hexadecimal-digit hexadecimal-digit
>>> hexadecimal-digit hexadecimal-digit
>>>
>>> Constraints
>>> 2 A universal character name shall not specify a character whose short identifier is less than
>>> 00A0 other than 0024 ($), 0040 (@), or 0060 ('), nor one in the range D800 through
>>> DFFF inclusive.73)
>>
>> In general, the constrained syntax could alternatively have been
>> described using only syntax rules. If a constraint was used, it's
>> generally because expressing the same idea with syntax rules would have
>> made it much more complex. For example:
...
> I, as always am only talking C90.
I gave the first example I could find of a semantic constraint. I was
only intending it as a proof of principle.
If you want to restrict your attention to constraints that were present
in C90, look for the C90 equivalent of the following C2011 constraint:
"At most, one storage-class specifier may be given in the declaration
specifiers in a declaration ..." (6.7.1p2). Something like that should
be present in C90, possibly with slightly different wording or a
different section number.
That is a purely syntactic constraint, but because the standard allows
storage-class-specifiers to be mixed freely with the other kinds of
declaration-specifiers (6.7p1), I don't see any way to impose that same
requirement using only syntax rules of the form used by the standard -
possibly I'm being insufficiently clever.
> But I don't see why the syntax you
> quote can't pass the details to semantics.
Possibly - but that's not relevant to my point - which is that this is
is, as currently written, a purely syntactic constraint.
--
James Kuyper
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Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-07 18:19 -0700
Re: Untyped Variables Lőrinczy Zsigmond <nospam@for.me> - 2015-08-08 06:53 +0200
Re: Untyped Variables James Kuyper <jameskuyper@verizon.net> - 2015-08-08 11:09 -0400
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-08 12:09 -0700
Re: Untyped Variables James Kuyper <jameskuyper@verizon.net> - 2015-08-08 14:24 -0400
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-08 12:54 -0700
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-08 16:06 -0700
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-08 17:29 -0700
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-09 17:52 -0700
Re: Untyped Variables Ian Collins <ian-news@hotmail.com> - 2015-08-10 12:57 +1200
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-10 08:41 -0700
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-10 17:06 -0700
Re: Untyped Variables Richard Damon <Richard@Damon-Family.org> - 2015-08-08 19:44 -0400
Re: Untyped Variables James Kuyper <jameskuyper@verizon.net> - 2015-08-08 20:34 -0400
Re: Untyped Variables glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-09 02:03 +0000
Re: Untyped Variables Richard Damon <Richard@Damon-Family.org> - 2015-08-08 22:52 -0400
Re: Untyped Variables glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-09 04:57 +0000
Re: Untyped Variables Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-08-09 09:58 -0600
Re: Untyped Variables Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-08-10 03:54 -0700
Re: Untyped Variables Richard Damon <Richard@Damon-Family.org> - 2015-08-09 16:59 -0400
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-09 18:02 -0700
Re: Untyped Variables James Kuyper <jameskuyper@verizon.net> - 2015-08-10 11:01 -0400
Re: Untyped Variables James Kuyper <jameskuyper@verizon.net> - 2015-08-10 13:20 -0400
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-10 16:54 -0700
Re: Untyped Variables James Kuyper <jameskuyper@verizon.net> - 2015-08-11 00:20 -0400
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-10 08:11 -0700
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-10 17:15 -0700
Re: Untyped Variables James Kuyper <jameskuyper@verizon.net> - 2015-08-11 00:30 -0400
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-11 16:50 -0700
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-11 17:24 -0700
Re: Untyped Variables Richard Heathfield <rjh@cpax.org.uk> - 2015-08-12 01:37 +0100
Re: Untyped Variables glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-12 04:46 +0000
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-12 18:12 -0700
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-13 12:08 -0700
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-13 16:25 -0700
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-14 10:36 -0700
Re: Untyped Variables Bartc <bc@freeuk.com> - 2015-08-14 19:13 +0100
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-11 07:58 -0700
Re: Untyped Variables richard@cogsci.ed.ac.uk (Richard Tobin) - 2015-08-10 13:53 +0000
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-10 08:29 -0700
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-10 17:01 -0700
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-10 17:42 -0700
Re: Untyped Variables glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-08-11 02:56 +0000
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-10 16:50 -0700
Re: Untyped Variables Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-11 01:39 +0100
Re: Untyped Variables Keith Thompson <kst-u@mib.org> - 2015-08-10 19:03 -0700
Re: Untyped Variables Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-11 11:21 +0100
Re: Untyped Variables David Kleinecke <dkleinecke@gmail.com> - 2015-08-11 16:37 -0700
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