Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > comp.lang.c > #62314

Re: A Note on Readability

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: A Note on Readability
Date 2015-05-19 11:23 -0700
Organization None to speak of
Message-ID <87oalg2zq0.fsf@kst-u.example.com> (permalink)
References (5 earlier) <67b5daac-4378-458c-a6d0-fbf4e20d8340@googlegroups.com> <mjahod$923$1@dont-email.me> <29103fb2-ce27-4c7f-a189-8ff170f5e246@googlegroups.com> <555A2A66.1040201@verizon.net> <70adeda1-3b83-4a96-b57b-59ac062f0bc6@googlegroups.com>

Show all headers | View raw


David Kleinecke <dkleinecke@gmail.com> writes:
> On Monday, May 18, 2015 at 11:07:42 AM UTC-7, James Kuyper wrote:
>> On 05/18/2015 01:38 PM, David Kleinecke wrote:
>> > On Sunday, May 17, 2015 at 10:06:31 AM UTC-7, Richard Heathfield wrote:
>> ...
>> >> You are mistaken. The naming rules /are/ part of the C language. See for 
>> >> example 4.1.2 of C89 or Section 7.1.3 of C99 onwards.
>> ...
>> > In my copy of the C90 standard there is no 4.1.2. and Part 4 - entitled
>> > Compliance - does not discuss naming rules.
>> 
>> C90 differs from C89 almost entirely by the addition of 3 sections at
>> the beginning required by ISO document conventions, with the result that
>> all other section numbers increased by 3. Thus, section 4.1.2 of C89
>> would correspond to 7.1.2 of C90. I don't have a copy of either
>> standard, so I cannot confirm that either section number is correct, but
>> it is section 7.1.3 in later versions of the standard, which I do have
>> copies of, so that puts it in the right general region of the document.
>
> In the C90 standard Part 7 is the Library. 7.1.2 describes Standard
> headers and 7.1.3 is about Reserved Headers does is in fact what you
> wanted. 
>
> Since I was copying GTK+ code and not advancing my own I don't feel very
> apologetic. Personally I never start a name with an underscore. Since
> GTK+ compiles (I assume) either gcc (assumed) does not enforce the rules
> about reserved headers or has a way to turn the enforcement off.

There are no rules to enforce.  The standard says that code outside the
implementation that uses identifiers that are reserved to the
implementation has undefined behavior.  There is no requirement for
compilers to detect or diagnose improper use of reserved identifiers.

If I write (assume this is part of a complete program):

    int n = 42;
    printf("%d\n", n);

it must print "42", or at least try to do so (assuming a conforming
hosted implementation).  If I write:

    int _N = 42;
    printf("%d\n", _N);

the behavior is undefined.  One very likely result is that it will print
"42".  Another possible result is that it will fail to compile because
<stdio.h> or the compiler uses _N for its own purposes.

> I assume it is the standards committee that wants to keep the reserved
> headers to themselves. 

You make it sound like the committee is hoarding identifiers for
some nefarious purpose.  I wouldn't put it that way.  The standards
committee wants to keep a particular set of identifiers reserved
for implementers, guaranteeing that other identifiers are available
for use in user code.  This is primarily for the benefit of C
programmers, who can depend on being able to use non-reserved
identifiers without fear of collisions (though collisions with
library code are still possible).

I asked you a few days ago:

    [...] Do you think that identifiers starting with underscores
    *shouldn't* be reserved to the implementation?  If so, how are
    implementations of the standard library supposed to be written
    without the risk of breaking user code?

I don't recall that you ever replied.

-- 
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"

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread


Thread

A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-06 18:54 -0700
  A Note on Readability asetofsymbols@gmail.com - 2015-05-06 23:08 -0700
    Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-07 07:34 +0100
      Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-07 12:22 -0700
        Re: A Note on Readability raltbos@xs4all.nl (Richard Bos) - 2015-05-17 10:50 +0000
          Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-17 09:40 -0700
            Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-17 18:06 +0100
              Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-18 10:38 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-18 14:07 -0400
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-19 10:07 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-19 11:23 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-20 08:41 -0700
                Re: A Note on Readability asetofsymbols@gmail.com - 2015-05-20 09:03 -0700
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 12:09 -0500
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-21 09:08 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-20 17:15 +0100
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 12:10 -0500
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-21 08:58 -0700
                Re: A Note on Readability glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-21 17:33 +0000
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-22 09:47 -0700
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 12:08 -0500
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-20 13:43 -0400
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-20 10:59 -0700
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 18:05 -0500
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-20 17:36 -0700
                Re: A Note on Readability Les Cargill <lcargill99@comcast.com> - 2015-05-20 22:12 -0500
                Re: A Note on Readability Philip Lantz <prl@canterey.us> - 2015-05-20 20:34 -0700
                Re: A Note on Readability glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-21 04:39 +0000
                Re: A Note on Readability Philip Lantz <prl@canterey.us> - 2015-05-21 17:41 -0700
                Re: A Note on Readability gwowen <gwowen@gmail.com> - 2015-05-21 01:14 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-21 09:26 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-21 10:33 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-22 09:42 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-22 11:53 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-23 10:01 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-23 14:53 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-24 09:18 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-24 13:13 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-25 09:38 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-25 12:40 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 10:56 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-26 12:35 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-27 10:08 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-27 11:07 -0700
                Re: A Note on Readability Robert Wessel <robertwessel2@yahoo.com> - 2015-05-27 20:17 -0500
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-25 09:56 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-25 13:05 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 09:58 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-26 18:16 +0100
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 10:55 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-26 12:11 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-26 12:01 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-27 09:58 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-27 18:11 +0100
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-28 12:11 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-28 12:55 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-29 10:08 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-06-01 18:54 +0100
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-10 11:29 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-11 09:06 -0700
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 13:42 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-12 09:20 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-12 11:24 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-13 08:48 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-13 12:38 -0400
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-13 10:34 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-13 14:43 -0400
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-13 12:18 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-13 15:27 -0400
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-14 08:45 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-14 09:05 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-14 09:41 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-14 10:26 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-15 19:59 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-14 12:25 -0400
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-13 13:46 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-07-14 08:33 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-13 11:17 -0700
                Re: A Note on Readability Richard Damon <Richard@Damon-Family.org> - 2015-07-13 21:06 -0400
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-07-13 22:38 -0400
                Re: A Note on Readability Richard Damon <Richard@Damon-Family.org> - 2015-07-15 08:19 -0400
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-20 09:10 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-07-13 11:00 -0700
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-15 08:11 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-27 10:57 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-24 09:51 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-24 13:36 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-25 10:00 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-25 13:05 -0700
                Re: A Note on Readability Philip Lantz <prl@canterey.us> - 2015-05-24 16:43 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-24 09:57 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-24 13:37 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-25 10:14 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-25 13:11 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 10:26 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-26 18:38 +0100
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-26 12:24 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-27 10:06 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-27 11:05 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-26 10:38 -0700
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-24 07:01 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-24 09:58 -0700
                Re: A Note on Readability Philip Lantz <prl@canterey.us> - 2015-05-25 00:45 -0700
                Re: A Note on Readability Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-10 11:09 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-21 09:04 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-21 10:36 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-22 09:56 -0700
                Re: A Note on Readability Robert Wessel <robertwessel2@yahoo.com> - 2015-05-22 12:16 -0500
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-22 14:14 -0400
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-23 09:49 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-22 11:55 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-22 11:58 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-20 10:26 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-18 11:08 -0700
                Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-19 10:09 -0700
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-18 20:40 +0100
            Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-17 14:34 -0400
              Re: A Note on Readability David Kleinecke <dkleinecke@gmail.com> - 2015-05-18 10:40 -0700
                Re: A Note on Readability Keith Thompson <kst-u@mib.org> - 2015-05-18 11:18 -0700
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-18 14:33 -0400
                Re: A Note on Readability Richard Heathfield <rjh@cpax.org.uk> - 2015-05-18 20:44 +0100
                Re: A Note on Readability James Kuyper <jameskuyper@verizon.net> - 2015-05-18 16:07 -0400

csiph-web