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Groups > comp.lang.c > #143592
| From | Tim Rentsch <tr.17687@z991.linuxsc.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: qsort() standard functions |
| Date | 2019-05-04 07:35 -0700 |
| Organization | A noiseless patient Spider |
| Message-ID | <86zho2i8yt.fsf@mailhub.linuxsc.com> (permalink) |
| References | (8 earlier) <20190427145541.4f9f1d28cc434e9136029307@gmail.com> <878svvsg52.fsf@bsb.me.uk> <c919ce5osb9vloiag3ugnusnjf40191gr2@4ax.com> <86h8acg5y5.fsf@mailhub.linuxsc.com> <20190502203521.9f93e01e3aa66851ce1ebfd3@gmail.com> |
Anton Shepelev <anton.txt@gmail.com> writes:
> Tim Rentsch:
>
>> My reaction is very much the opposite. The point of
>> providing the 'extra' parameter is for the convenience of
>> the client, and so should accommodate as wide a range of
>> use cases as it reasonably can. We do not know that a
>> client data area will be used only with calls to the sort
>> function - it might be used in conjunction with several
>> different callback functions, for all sorts (no pun
>> intended) of purposes.
>
> You mean the data to which a pointer is passed to the sort
> routing as the `extra' parameter can also be used elsewhere
> in the program outside the sort routine?
Yes, and in particular with other callback functions.
> If so, the `const'
> modifier in the sort routine does not in any away affect
> these other usages, does it?
My point is that one bears on the other and so, yes, it
can affect other code that needs the same callback data.
>> Furthermore the combination of a function pointer and a
>> void * pointer is a common idiom in C to provide the
>> functionality of a closure. Surely the idiom expects that
>> data in the "closure" might be modified, and so a 'void *'
>> type rather than a 'const void *' type is more usual, and
>> more appropriate. Since the 'extra' parameter (almost
>> always) needs to be converted by the callback function,
>> that function can choose a 'const Foo *' type if const-
>> ness is important there. Forcing client code to put in an
>> unnecessary cast says in effect the sort routine knows
>> better than its callers. Service routines such as sort
>> should accommodate their callers, not the other way
>> around.
>
> I understand your appeal to generality but miss your point
> about the unnecessary cast. The cast is always there,
> whether to `Foo *' or to `const Foo *'. I should say it is
> unavoidable rather than unnecessary.
When the parameter is const void * (but the use is not):
int
some_callback_1( const void *vdata /*, other parameters */ ){
Foo *data = (void *)vdata;
/* ... rest of function ... */
return 0;
}
When the parameter is just void *, with no const (but the use is
const):
int
some_callback_2( void *vdata /*, other parameters */ ){
const Foo *data = vdata;
/* ... rest of function ... */
return 0;
}
The first case needs a cast. The second case doesn't need one,
and doesn't have one (and still wouldn't if the declaration were
'Foo *data = ...' without the 'const').
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qsort() standard functions rick.c.hodgin@gmail.com - 2019-04-24 09:08 -0700
Re: qsort() standard functions gazelle@shell.xmission.com (Kenny McCormack) - 2019-04-24 16:12 +0000
Re: qsort() standard functions rick.c.hodgin@gmail.com - 2019-04-24 09:18 -0700
Re: qsort() standard functions Chad <cdalten@gmail.com> - 2019-05-02 12:02 -0700
Re: qsort() standard functions Real Troll <real.troll@trolls.com> - 2019-04-24 22:30 -0400
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 19:32 -0700
Re: qsort() standard functions Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-04-25 10:19 +0000
Re: qsort() standard functions rick.c.hodgin@gmail.com - 2019-04-25 04:09 -0700
Re: qsort() standard functions Richard Damon <Richard@Damon-Family.org> - 2019-04-25 08:13 -0400
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-25 06:39 -0700
Re: qsort() standard functions already5chosen@yahoo.com - 2019-04-25 07:23 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-25 00:39 -0700
Re: qsort() standard functions Real Troll <Real.Troll@Trolls.com> - 2019-04-25 23:27 +0100
Re: qsort() standard functions John Bode <jfbode1029@gmail.com> - 2019-04-24 09:34 -0700
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 09:47 -0700
Re: qsort() standard functions John Bode <jfbode1029@gmail.com> - 2019-04-24 09:47 -0700
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 12:54 -0400
Re: qsort() standard functions John Bode <jfbode1029@gmail.com> - 2019-04-24 11:33 -0700
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 14:41 -0400
Re: qsort() standard functions John Bode <jfbode1029@gmail.com> - 2019-04-24 11:52 -0700
Re: qsort() standard functions gazelle@shell.xmission.com (Kenny McCormack) - 2019-04-24 19:12 +0000
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 16:05 -0400
Re: qsort() standard functions queequeg@trust.no1 (Queequeg) - 2019-04-24 20:39 +0000
Re: qsort() standard functions James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-04-24 16:33 -0700
Re: qsort() standard functions gazelle@shell.xmission.com (Kenny McCormack) - 2019-04-24 19:18 +0000
Re: qsort() standard functions Bart <bc@freeuk.com> - 2019-04-24 20:28 +0100
Re: qsort() standard functions gazelle@shell.xmission.com (Kenny McCormack) - 2019-04-24 21:27 +0000
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 12:31 -0700
Re: qsort() standard functions John Bode <jfbode1029@gmail.com> - 2019-04-24 13:02 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 13:41 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 14:00 -0700
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-04-25 00:22 +0300
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 15:04 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 15:20 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 15:40 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 15:57 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 16:06 -0700
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-04-25 23:49 +0300
Re: qsort() standard functions Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-04-25 22:45 +0100
Re: qsort() standard functions Bart <bc@freeuk.com> - 2019-04-25 23:00 +0100
Re: qsort() standard functions Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-04-25 23:24 +0100
Re: qsort() standard functions Real Troll <Real.Troll@Trolls.com> - 2019-04-25 23:20 +0100
Re: qsort() standard functions Anton Shepelev <anton.txt@g{oogle}mail.com> - 2019-04-26 13:06 +0300
Re: qsort() standard functions Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-04-26 13:38 +0100
Re: qsort() standard functions Anton Shepelev <anton.txt@g{oogle}mail.com> - 2019-04-26 16:43 +0300
Re: qsort() standard functions Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-04-26 17:46 +0100
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-04-27 14:55 +0300
Re: qsort() standard functions Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-04-27 14:59 +0100
Re: qsort() standard functions Robert Wessel <robertwessel2@yahoo.com> - 2019-04-27 11:41 -0500
Re: qsort() standard functions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-05-02 09:46 -0700
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-05-02 20:35 +0300
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-05-02 15:35 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-05-05 04:39 -0700
Re: qsort() standard functions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-05-04 07:35 -0700
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-05-05 00:01 +0300
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-05-02 15:11 +0300
Re: qsort() standard functions Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-05-02 16:36 +0100
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-04-27 14:47 +0300
Re: qsort() standard functions Robert Wessel <robertwessel2@yahoo.com> - 2019-04-27 08:30 -0500
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-05-02 14:52 +0300
Re: qsort() standard functions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-05-04 07:13 -0700
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-05-05 22:57 +0300
Re: qsort() standard functions David Brown <david.brown@hesbynett.no> - 2019-05-06 10:09 +0200
Re: qsort() standard functions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-06-01 05:22 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-25 17:09 -0700
Re: qsort() standard functions Bart <bc@freeuk.com> - 2019-04-26 10:58 +0100
Re: qsort() standard functions mark.bluemel@gmail.com - 2019-04-26 03:59 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-26 06:34 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-26 07:16 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-26 07:45 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-26 08:29 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-26 12:06 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-26 13:09 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-26 13:37 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-26 14:05 -0700
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-04-27 14:59 +0300
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-27 06:19 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-27 06:32 -0700
Re: qsort() standard functions Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-04-24 10:54 -0600
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 10:10 -0700
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-04-25 00:06 +0300
Re: qsort() standard functions scott@slp53.sl.home (Scott Lurndal) - 2019-04-24 17:37 +0000
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 10:56 -0700
Re: qsort() standard functions Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-04-24 12:12 -0600
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 14:27 -0400
Re: qsort() standard functions John Bode <jfbode1029@gmail.com> - 2019-04-24 11:44 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 11:57 -0700
Re: qsort() standard functions fir <profesor.fir@gmail.com> - 2019-04-24 12:04 -0700
Re: qsort() standard functions nobody@example.org (Scott) - 2019-04-25 01:16 +0000
Re: qsort() standard functions James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-04-24 21:38 -0400
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 14:42 -0400
Re: qsort() standard functions David Brown <david.brown@hesbynett.no> - 2019-04-24 22:13 +0200
Re: qsort() standard functions queequeg@trust.no1 (Queequeg) - 2019-04-24 20:46 +0000
Re: qsort() standard functions jadill33@gmail.com - 2019-04-24 14:01 -0700
Re: qsort() standard functions "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2019-04-24 15:41 -0700
Re: qsort() standard functions "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-04-26 22:24 +0800
Re: qsort() standard functions Anton Shepelev <anton.txt@gmail.com> - 2019-05-02 15:05 +0300
Re: qsort() standard functions "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-05-03 17:02 +0800
Re: qsort() standard functions Chad <cdalten@gmail.com> - 2019-05-03 10:10 -0700
Re: qsort() standard functions "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-05-04 01:22 +0800
Re: qsort() standard functions Chad <cdalten@gmail.com> - 2019-05-03 15:14 -0700
[OT]Eternal.... programmer? "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2019-05-04 06:20 +0800
Re: [OT]Eternal.... programmer? Chad <cdalten@gmail.com> - 2019-05-04 05:53 -0700
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