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Groups > comp.lang.c > #120621
| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: const and the C type system |
| Date | 2017-09-30 13:35 -0700 |
| Organization | None to speak of |
| Message-ID | <ln4lrjudq6.fsf@kst-u.example.com> (permalink) |
| References | (1 earlier) <oql21t$mh6$1@dont-email.me> <2c5a4b5b-ec8b-44fe-a77c-e26a0e1c5bb9@googlegroups.com> <NPrzB.979054$gM6.814414@fx03.am4> <oqohtj$f2j$1@dont-email.me> <fKQzB.1787364$DB.699792@fx04.am4> |
bartc <bc@freeuk.com> writes:
> On 30/09/2017 17:48, David Brown wrote:
>> On 29/09/17 15:24, bartc wrote:
>>> I think you're the only person ever to have voiced the same misgivings
>>> about C's failings in this area as I have.
>>
>> Why would you think that?
>
> The topic has been discussed many times, and the attitudes have always
> been the same.
Wrong.
>> The methods available in C for defining constants are not as good as
>> they could be - I have never seem anyone deny that. But they are also
>> not nearly as bad as some people (such as yourself and Thiago) seem to
>> think.
>
> As I said, there is a very simple, lightweight solution to the problem,
> and they have been plenty of opportunities to introduce it, but no one
> is interested in that.
You proposed:
constant const1 1;
That's a new keyword and a new syntax that I've never seen anyone
else propose. You expect the committee to adopt it without ever
having heard of it. Meanwhile, C++ has an existing solution (`const
int n = 42;` making n a constant expression) that could be adopted
by C. As it happens, clang appears to implement it as an extension;
gcc does not.
> They would rather look towards a heavyweight answer like C++'s
> constexpr, which is like C's const variable but even more complicated.
> That's not going to happen anytime time soon, so C's is stuck with what
> it has.
I don't recall anyone mentioning constexpr. But now that you
mention it, a simpler version of C++'s constexpr might be an even
better solution. I don't think I'd suggest supporting constexpr
functions, but constexpr "variables" might be something to consider.
For example, in C++
constexpr int n = 42;
makes `n` a constant expression and requires the initializer to be a
constant expression. (I'm a bit surprised to find that `&n` is legal;
perhaps C needn't permit that.) I find it cleaner than the C++
treatment of
const int n = 42;
because (a) the compiler enforces making the initializer a constant
expression and (b) it doesn't blur the distinction between "constant"
(meaning evaluable at compile time) and "const" (meaning read-only).
[...]
> Meanwhile, suppose you had a task to automatically translate syntax
> which already has that suggested feature, into readable C; how would you
> do that?
Readability of intermediate code is not usually a requirement, but ok.
[...]
> #define is not an option, since the original uses
> identifiers with normal scope rules.
Your translator could generate #undef directives at the end of the scope.
[...]
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-28 19:51 -0700
Re: const and the C type system Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-09-28 21:32 -0600
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-29 05:45 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-09-29 14:05 +0100
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-29 06:17 -0700
Re: const and the C type system asetofsymbols@gmail.com - 2017-10-01 22:35 -0700
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-09-29 10:59 +0200
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-29 06:06 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-09-29 14:24 +0100
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-29 06:52 -0700
Re: const and the C type system jameskuyper@verizon.net - 2017-09-29 09:17 -0700
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-29 10:50 -0700
Re: const and the C type system jameskuyper@verizon.net - 2017-09-29 11:06 -0700
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-29 11:27 -0700
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-30 13:13 -0700
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-30 13:31 -0700
Re: const and the C type system Keith Thompson <kst-u@mib.org> - 2017-09-29 09:10 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-09-29 18:33 +0100
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-29 11:10 -0700
Re: const and the C type system Ian Collins <ian-news@hotmail.com> - 2017-09-30 08:29 +1300
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-09-30 18:48 +0200
Re: const and the C type system bartc <bc@freeuk.com> - 2017-09-30 18:44 +0100
Re: const and the C type system Ian Collins <ian-news@hotmail.com> - 2017-10-01 09:12 +1300
Re: const and the C type system bartc <bc@freeuk.com> - 2017-09-30 21:50 +0100
Re: const and the C type system Ian Collins <ian-news@hotmail.com> - 2017-10-01 10:10 +1300
Re: const and the C type system bartc <bc@freeuk.com> - 2017-09-30 23:17 +0100
Re: const and the C type system Ian Collins <ian-news@hotmail.com> - 2017-10-01 11:38 +1300
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 00:44 +0100
Re: const and the C type system Ian Collins <ian-news@hotmail.com> - 2017-10-01 14:33 +1300
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 10:42 +0100
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-01 19:58 +0200
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 21:30 +0100
Re: const and the C type system Ian Collins <ian-news@hotmail.com> - 2017-10-02 17:48 +1300
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-02 11:14 +0100
Re: const and the C type system Ian Collins <ian-news@hotmail.com> - 2017-10-02 23:22 +1300
Re: const and the C type system Richard Damon <Richard@Damon-Family.org> - 2017-10-01 13:58 -0400
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-01 18:20 +0200
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 18:41 +0100
Re: const and the C type system supercat@casperkitty.com - 2017-10-01 12:03 -0700
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-01 23:05 +0200
Re: const and the C type system supercat@casperkitty.com - 2017-10-01 15:58 -0700
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-02 09:56 +0200
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-02 00:24 +0100
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-02 12:20 +0200
Re: const and the C type system Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2017-10-02 06:03 -0700
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-10-02 06:34 -0700
Re: const and the C type system supercat@casperkitty.com - 2017-10-02 23:38 -0700
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-10-01 13:03 -0700
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-01 23:12 +0200
Re: const and the C type system supercat@casperkitty.com - 2017-10-01 11:12 -0700
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-01 13:48 +0200
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 14:13 +0100
Re: const and the C type system supercat <flatfinger@casperkitty.com> - 2017-10-01 10:32 -0700
Re: const and the C type system supercat@casperkitty.com - 2017-09-30 13:52 -0700
Re: const and the C type system Keith Thompson <kst-u@mib.org> - 2017-09-30 13:35 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-09-30 21:58 +0100
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 12:03 +0100
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-30 14:00 -0700
Re: const and the C type system Keith Thompson <kst-u@mib.org> - 2017-09-30 15:33 -0700
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-10-01 12:45 -0700
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-01 13:13 +0200
Re: const and the C type system Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2017-10-01 05:22 -0700
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-01 20:06 +0200
Re: const and the C type system supercat@casperkitty.com - 2017-10-01 12:16 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 21:01 +0100
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-10-01 13:21 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 21:50 +0100
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-10-02 05:35 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-02 14:01 +0100
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-10-02 06:29 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-02 15:19 +0100
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-01 23:19 +0200
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 22:33 +0100
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-02 00:10 +0200
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 14:13 +0100
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-01 22:46 +0200
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 21:57 +0100
Re: const and the C type system Keith Thompson <kst-u@mib.org> - 2017-10-01 14:09 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-01 23:54 +0100
Re: const and the C type system Keith Thompson <kst-u@mib.org> - 2017-10-01 19:12 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-02 11:36 +0100
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-02 12:45 +0200
Re: const and the C type system Keith Thompson <kst-u@mib.org> - 2017-10-02 09:40 -0700
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-02 19:33 +0100
Re: const and the C type system scott@slp53.sl.home (Scott Lurndal) - 2017-10-02 19:09 +0000
Re: const and the C type system Ian Collins <ian-news@hotmail.com> - 2017-10-03 08:12 +1300
Re: const and the C type system bartc <bc@freeuk.com> - 2017-10-02 20:30 +0100
Re: const and the C type system Keith Thompson <kst-u@mib.org> - 2017-10-02 12:37 -0700
Re: const and the C type system jadill33@gmail.com - 2017-10-02 12:49 -0700
Re: const and the C type system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2017-10-06 20:47 +0000
Re: const and the C type system Keith Thompson <kst-u@mib.org> - 2017-10-06 15:41 -0700
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-10-02 12:42 +0200
Re: const and the C type system Gareth Owen <gwowen@gmail.com> - 2017-10-01 21:18 +0100
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-30 12:22 -0700
Re: const and the C type system David Brown <david.brown@hesbynett.no> - 2017-09-30 18:44 +0200
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-29 07:01 -0700
Re: const and the C type system Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-29 20:18 +0100
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-09-29 12:40 -0700
Re: const and the C type system Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-09-29 21:28 +0100
Re: const and the C type system fir <profesor.fir@gmail.com> - 2017-09-29 08:21 -0700
Re: const and the C type system fir <profesor.fir@gmail.com> - 2017-09-29 08:38 -0700
Re: const and the C type system John Bode <jfbode1029@gmail.com> - 2017-10-02 09:20 -0700
Re: const and the C type system Thiago Adams <thiago.adams@gmail.com> - 2017-10-02 09:53 -0700
Re: const and the C type system Jorgen Grahn <grahn+nntp@snipabacken.se> - 2017-10-09 13:27 +0000
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