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| Newsgroups | comp.lang.c |
|---|---|
| From | Greg Martin <greg.at.softsprocket@dot.com> |
| Subject | Re: New directions in C: Default arguments |
| References | (7 earlier) <3f5b38ce-dd98-4ba6-b7a7-0ab9e8b89d44@googlegroups.com> <14f98f84-8033-4b26-ada1-305d89491e7e@googlegroups.com> <me51nf$2ha$1@dont-email.me> <87mw3d0xcl.fsf@kst-u.example.com> <me70mb$h53$1@dont-email.me> |
| Organization | SoftSprocket |
| Message-ID | <_4ENw.20099$7U.13751@fx31.iad> (permalink) |
| Date | 2015-03-16 17:07 +0000 |
On 2015-03-16, Martin Shobe <martin.shobe@yahoo.com> wrote:
> On 3/16/2015 10:35 AM, Keith Thompson wrote:
>> Bartc <bc@freeuk.com> writes:
>>> On 15/03/2015 22:03, fir wrote:
>>>> besides that remarks (that ere heavily partial) one there could
>>>> consider a bot more general form (mentioned) with any interface to
>>>> called functions (rest is default)
>>>>
>>>> //foo has 17 args
>>>>
>>>> foo(x=10, y=30); // 15 other args are default
>>>>
>>>> foo(txt="aaa", y=30, z=12);// etc
>>>>
>>>> can be done and could be considered usefull but seems probably wastefull
>>>> (not c style , though may be some uglier api style like microsoft etc)
>>>
>>> Presumably the C style is to have to put in all 17 parameters, usually
>>> without annotation, which means studying the function docs while
>>> writing it (and still having to count along to see which argument is
>>> which), and again when someone else is trying to read it.
>>>
>>> Defaults arguments and keyword parameters are fairly straightforward
>>> enhancements, they are easy to implement (I've done it), and easy for
>>> users to grasp. In other words, a no-brainer.
>>>
>>> However, I believe the proposal in this thread is to only have default
>>> arguments, and to only allow trailing arguments to be omitted. Still
>>> useful, but keyword parameters thrown in would have been good too.
>>
>> One problem with keyword parameters is that C doesn't require consistent
>> parameter names in all declarations. Parameter names are not part of
>> the "signature" of a function (because in current C they're irrelevant
>> to the caller).
>>
>> For example, given a definition like:
>>
>> void func(int x, int y) { /* ... */ }
>>
>> any of these declarations would be compatible:
>>
>> void func(int, int);
>> void func(int x, int y);
>> void func(int y, int x);
>>
>> Probably the simplest rule (that would not break existing code) would be
>> to make named parameters consistent with the most recent visible
>> declaration.
>
> Another simple rule would be to require that keyword parameters are
> identified explicitly in the prototype and require that those be named
> consistently.
>
> For example (using . to identify keywords as seen else thread) the
> following would all be compatible.
>
> void func(int w, int x, int .y, int .z);
> void func(int x, int w, int .y, int .z);
> void func(int, int, int .y, int .z);
>
> However, the following would not be compatible with the above and would
> require a diagnostic if they both appeared in the same scope.
>
> void func(int w, int x, int .z, int .y);
>
> Martin Shobe
>
What would this buy you, over using a structure to pass the arguments?
I'm not sure it would be worth the effort.
A structure as an argument allows some defaulting of arguments as well
as implicit named parameters. Admittedly the default arguments are
limited.
--
http://www.softsprocket.com
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New directions in C: Default arguments jacob navia <jacob@spamsink.net> - 2015-03-14 23:11 +0100
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-14 18:17 -0700
Re: New directions in C: Default arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-03-15 11:25 +0000
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-15 07:18 -0700
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-15 14:32 +0000
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-15 08:30 -0700
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-15 09:05 -0700
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-15 10:15 -0700
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-15 15:03 -0700
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-15 22:40 +0000
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-15 16:04 -0700
Re: New directions in C: Default arguments Keith Thompson <kst-u@mib.org> - 2015-03-16 08:35 -0700
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-16 16:45 +0100
Re: New directions in C: Default arguments Keith Thompson <kst-u@mib.org> - 2015-03-16 11:36 -0700
Re: New directions in C: Default arguments Philip Lantz <prl@canterey.us> - 2015-03-17 02:09 -0700
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-17 12:44 +0000
Re: New directions in C: Default arguments Philip Lantz <prl@canterey.us> - 2015-03-17 11:07 -0700
Re: New directions in C: Default arguments Martin Shobe <martin.shobe@yahoo.com> - 2015-03-16 11:35 -0500
Re: New directions in C: Default arguments Greg Martin <greg.at.softsprocket@dot.com> - 2015-03-16 17:07 +0000
Re: New directions in C: Default arguments Martin Shobe <martin.shobe@yahoo.com> - 2015-03-16 12:40 -0500
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-16 18:12 +0000
Re: New directions in C: Default arguments Greg Martin <greg.at.softsprocket@dot.com> - 2015-03-16 18:30 +0000
Re: New directions in C: Default arguments Martin Shobe <martin.shobe@yahoo.com> - 2015-03-16 13:52 -0500
Re: New directions in C: Default arguments Greg Martin <greg.at.softsprocket@dot.com> - 2015-03-16 19:35 +0000
Re: New directions in C: Default arguments Martin Shobe <martin.shobe@yahoo.com> - 2015-03-16 14:52 -0500
Re: New directions in C: Default arguments Greg Martin <greg.at.softsprocket@dot.com> - 2015-03-16 20:27 +0000
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-16 19:44 +0000
Re: New directions in C: Default arguments Greg Martin <greg.at.softsprocket@dot.com> - 2015-03-16 19:55 +0000
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-16 20:23 +0000
Re: New directions in C: Default arguments Greg Martin <greg.at.softsprocket@dot.com> - 2015-03-16 20:53 +0000
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-16 14:33 -0700
Re: New directions in C: Default arguments Keith Thompson <kst-u@mib.org> - 2015-03-16 11:44 -0700
Re: New directions in C: Default arguments Martin Shobe <martin.shobe@yahoo.com> - 2015-03-16 13:59 -0500
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-15 01:33 +0000
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-15 00:59 -0700
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-15 23:45 +0100
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-15 16:21 -0700
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-16 11:41 +0100
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-16 11:13 +0000
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-16 13:19 +0100
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-16 12:38 +0000
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-16 13:51 +0100
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-16 13:21 +0000
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-16 15:12 +0100
Re: New directions in C: Default arguments Richard Heathfield <rjh@cpax.org.uk> - 2015-03-16 14:24 +0000
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-16 16:09 +0100
Re: New directions in C: Default arguments Richard Heathfield <rjh@cpax.org.uk> - 2015-03-16 18:11 +0000
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-17 13:23 +0100
Re: New directions in C: Default arguments Richard Heathfield <rjh@cpax.org.uk> - 2015-03-17 12:28 +0000
Re: New directions in C: Default arguments jacob navia <jacob@spamsink.net> - 2015-03-17 13:33 +0100
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-17 08:20 -0700
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-17 15:16 -0700
Re: New directions in C: Default arguments jacob navia <jacob@spamsink.net> - 2015-03-16 11:38 +0100
Re: New directions in C: Default arguments Bartc <bc@freeuk.com> - 2015-03-16 10:51 +0000
Re: New directions in C: Default arguments raltbos@xs4all.nl (Richard Bos) - 2015-03-16 13:47 +0000
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-16 13:20 +0100
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-16 10:43 -0700
Re: New directions in C: Default arguments David Brown <david.brown@hesbynett.no> - 2015-03-17 13:18 +0100
Re: New directions in C: Default arguments bert <bert.hutchings@btinternet.com> - 2015-03-15 08:25 -0700
Re: New directions in C: Default arguments jacob navia <jacob@spamsink.net> - 2015-03-15 18:16 +0100
Re: New directions in C: Default arguments Michael Angelo Ravera <maravera@prodigy.net> - 2015-03-16 00:38 -0700
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-16 01:03 -0700
Re: New directions in C: Default arguments Robert Wessel <robertwessel2@yahoo.com> - 2015-03-16 09:04 -0500
Re: New directions in C: Default arguments Michael Angelo Ravera <maravera@prodigy.net> - 2015-03-17 00:22 -0700
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-17 01:08 -0700
Re: New directions in C: Default arguments fir <profesor.fir@gmail.com> - 2015-03-19 01:37 -0700
Re: New directions in C: Default arguments asetofsymbols@gmail.com - 2015-03-20 00:45 -0700
Re: New directions in C: Default arguments Robert Wessel <robertwessel2@yahoo.com> - 2015-03-17 22:17 -0500
Re: New directions in C: Default arguments Michael Angelo Ravera <maravera@prodigy.net> - 2015-03-18 15:55 -0700
Re: New directions in C: Default arguments gwowen <gwowen@gmail.com> - 2015-03-16 01:07 -0700
Re: New directions in C: Default arguments Keith Thompson <kst-u@mib.org> - 2015-03-16 08:18 -0700
Re: New directions in C: Default arguments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-03-16 17:35 +0000
Definitions vs. Prototypes (Was: New directions in C: Default arguments) gazelle@shell.xmission.com (Kenny McCormack) - 2015-03-16 17:55 +0000
Re: New directions in C: Default arguments Kaz Kylheku <kaz@kylheku.com> - 2015-03-16 20:21 +0000
Re: New directions in C: Default arguments jacob navia <jacob@spamsink.net> - 2015-03-16 22:44 +0100
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