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Re: calling argumentless function with argument

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: calling argumentless function with argument
Date 2019-01-05 14:58 +0000
Organization A noiseless patient Spider
Message-ID <87ef9rtakz.fsf@bsb.me.uk> (permalink)
References <g99egeFi15cU1@mid.uni-berlin.de> <g9bp36F2osvU1@mid.uni-berlin.de> <q0qfp7$vnu$1@dont-email.me>

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David Brown <david.brown@hesbynett.no> writes:

> On 05/01/2019 14:17, Jens Thoms Toerring wrote:
<snip>
>> Unfortunately, for historical reasons some of these func-
>> tions accept a pointer, while others accept no argument.
>> To minimize the amount of work to implement this and lower
>> the bar to adopting the new system, it would be helpful if
>> the existing functions could be used without modifications.
>> For that being able to call a function that does not accept
>> arguments with an argument could be quite nice. As it stands
>> we have to change all these functions to accept an argument
>> that's ignored anyway, and to hunt down all other calls of
>> the functions and add a basically useless argument to all
>> of them.
>>
>> Of course, this isn't just about energy meters, there
>> are quite a number of other subsystems where it would be
>> better if "events" could be raised and then dealt with
>> by a central instance, distributing the information
>> to all subsystems that have registered their interest.
>
> It sounds like you need to get an abstraction layer in here somewhere
> so that you can make all these different modules look the same to the
> higher level.  Then your events or callbacks all have the same types
> and parameters, and it is the abstraction part for each module that
> translates to the module's individual requirements.  With care, such
> abstractions can have little or no overhead.
>
> A common part of this is to use a pointer to a struct for passing data
> around.  That avoids having different sets of parameters for the
> functions.

Or, quite often, just a void *.  This works well when called function
knows what sort of thing will be passed to it, and that is very often
the case.  This avoids having to find some common struct that suits all
interfaces both those known now and in those that my be needed in the
future.

<snip>
-- 
Ben.

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Thread

calling argumentless function with argument jt@toerring.de (Jens Thoms Toerring) - 2019-01-04 16:04 +0000
  Re: calling argumentless function with argument David Brown <david.brown@hesbynett.no> - 2019-01-04 17:34 +0100
    Re: calling argumentless function with argument Bart <bc@freeuk.com> - 2019-01-04 17:30 +0000
      Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-04 09:50 -0800
        Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-05 05:58 -0800
          Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-05 07:56 -0800
            Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-05 10:56 -0800
              Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-05 14:55 -0800
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 01:29 +0100
                Re: calling argumentless function with argument Bart <bc@freeuk.com> - 2019-01-06 02:20 +0000
                Re: calling argumentless function with argument Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-06 02:51 +0000
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 12:12 +0100
                Re: calling argumentless function with argument Bart <bc@freeuk.com> - 2019-01-06 11:53 +0000
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 12:58 +0100
                Re: calling argumentless function with argument Bart <bc@freeuk.com> - 2019-01-06 11:45 +0000
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 12:58 +0100
                Re: calling argumentless function with argument Bart <bc@freeuk.com> - 2019-01-06 12:24 +0000
                Re: calling argumentless function with argument Keith Thompson <kst-u@mib.org> - 2019-01-06 04:34 -0800
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 13:41 +0100
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 04:10 -0800
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 13:51 +0100
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 13:56 +0100
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 05:20 -0800
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 16:08 +0100
                Re: calling argumentless function with argument Keith Thompson <kst-u@mib.org> - 2019-01-06 15:59 -0800
                Re: calling argumentless function with argument Bart <bc@freeuk.com> - 2019-01-06 13:42 +0000
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 06:22 -0800
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 16:19 +0100
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 07:42 -0800
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 08:05 -0800
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 08:30 -0800
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 17:44 +0100
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 08:54 -0800
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-07 08:02 -0800
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-07 08:07 -0800
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-07 09:16 -0800
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-07 09:40 -0800
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-07 09:57 -0800
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-09 02:23 -0800
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 16:17 +0100
                Re: calling argumentless function with argument Bart <bc@freeuk.com> - 2019-01-06 16:56 +0000
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 09:12 -0800
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 12:39 -0800
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 18:26 +0100
                Re: calling argumentless function with argument Bart <bc@freeuk.com> - 2019-01-06 18:52 +0000
                Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-06 02:32 -0800
                Re: calling argumentless function with argument Keith Thompson <kst-u@mib.org> - 2019-01-06 04:38 -0800
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 13:42 +0100
                Re: calling argumentless function with argument Robert Wessel <robertwessel2@yahoo.com> - 2019-01-06 10:27 -0600
                Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-06 17:47 +0100
      Re: calling argumentless function with argument David Brown <david.brown@hesbynett.no> - 2019-01-04 19:30 +0100
      Re: calling argumentless function with argument Keith Thompson <kst-u@mib.org> - 2019-01-04 10:55 -0800
      Re: calling argumentless function with argument Robert Wessel <robertwessel2@yahoo.com> - 2019-01-05 00:16 -0600
    Re: calling argumentless function with argument queequeg@trust.no1 (Queequeg) - 2019-01-07 10:43 +0000
      Re: calling argumentless function with argument Robert Wessel <robertwessel2@yahoo.com> - 2019-01-07 16:25 -0600
  Re: calling argumentless function with argument Barry Schwarz <schwarzb@dqel.com> - 2019-01-04 09:54 -0800
  Re: calling argumentless function with argument Thiago Adams <thiago.adams@gmail.com> - 2019-01-04 10:26 -0800
    Re: calling argumentless function with argument Keith Thompson <kst-u@mib.org> - 2019-01-04 12:07 -0800
  Re: calling argumentless function with argument James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-04 15:03 -0500
    Re: calling argumentless function with argument Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-05 00:04 +0000
      Re: calling argumentless function with argument James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-05 22:36 -0500
  Re: calling argumentless function with argument jt@toerring.de (Jens Thoms Toerring) - 2019-01-05 13:17 +0000
    Re: calling argumentless function with argument fir <profesor.fir@gmail.com> - 2019-01-05 06:06 -0800
    Re: calling argumentless function with argument David Brown <david.brown@hesbynett.no> - 2019-01-05 15:42 +0100
      Re: calling argumentless function with argument Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-05 14:58 +0000
    Re: calling argumentless function with argument "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-05 16:11 +0100
    Re: calling argumentless function with argument Richard Damon <Richard@Damon-Family.org> - 2019-01-05 11:23 -0500
      Re: calling argumentless function with argument Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-05 16:53 +0000
        Re: calling argumentless function with argument Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-06 00:46 +0000

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