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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: A Note on Readability |
| Date | 2015-05-21 10:33 -0700 |
| Organization | None to speak of |
| Message-ID | <87h9r5u97m.fsf@kst-u.example.com> (permalink) |
| References | (10 earlier) <87oalg2zq0.fsf@kst-u.example.com> <792ce9c8-075c-4b19-8a2f-ac75dab1a178@googlegroups.com> <mjiel8$f7c$1@dont-email.me> <87y4kj1667.fsf@kst-u.example.com> <d265f45e-8de1-4c52-9d08-b9c760e3d3e3@googlegroups.com> |
David Kleinecke <dkleinecke@gmail.com> writes:
> On Wednesday, May 20, 2015 at 10:59:36 AM UTC-7, Keith Thompson wrote:
>> Les Cargill <lcargill99@comcast.com> writes:
>> [...]
>> > You *CAN* reuse reserved identifiers by:
>> > - macro substitution.
>> > - the use of the "static" keyword
>>
>> You cannot safely reuse identifiers starting with two underscores,
>> or with an underscore and an uppercase letter. They may be defined
>> by the standard library as macros, and a call to a standard library
>> function might use a macro that depends on such an identifier.
>>
>> Perhaps you can be safe if you don't call any standard library
>> functions, or if you call them in a way that bypasses any macro
>> definition. Conceivably an implementation might even forbid or
>> ignore a #define that renames a reserved identifier, though I'm
>> not certain of the legality of doing so.
>>
>> But since I can, with zero cost, simply avoid defining reserved
>> identifiers, I don't have to worry about it.
>
> I never personally advocated using leading underscores and I personally
> never do (with a few carefully designed exceptions). I just quoted
> somebody else's code that broke the underscore rules and remarked
> that I didn't mind them doing that.
Ok, nobody is requiring you to mind it, so I see no problem so far.
> The specific example I offered was an version of statements like
> typedef struct _GeditTab GeditTab;
> in GTK+. But note where that "_G..." indentifier is.
>
> In the C90 standard document this restriction on identifiers is part of
> the Standard Library not the C language.
It's part of the C standard. Section 7 of the C standard is no less
relevant than section 6, at least for hosted implementations.
> Perhaps the standard(s) need to explicitly allow free use of underscores
> in identifiers which are struct/union tags and - for that matter struct
> members as well. Even local variables appear to have no reason to be
> restricted.
There's a very good reason. Implementations may define such identifiers
*as macros*, either by defining them in a standard header file or by
predefining them in the compiler.
If an implementation predefines _GeditTab as the constant 42,
then the declaration
typedef struct _GeditTab GeditTab;
will fail to compile. GTK+ gets away with it because, apparently,
no implementations under which it's compiled happen to predefine
_GeditTab.
> I don't care enough to mention this to the standard committee.
--
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
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
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