Groups > comp.lang.c > #162042

Re: How to disambiguate macro?

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.lang.c
Subject	Re: How to disambiguate macro?
Date	2021-07-22 18:15 +0200
Organization	A noiseless patient Spider
Message-ID	<sdc5i6$4l2$1@dont-email.me> (permalink)
References	(11 earlier) <sd9ib5$qh1$1@dont-email.me> <sd9mhe$q8b$1@dont-email.me> <sd9tkt$edf$1@dont-email.me> <sdb4an$56m$1@dont-email.me> <sdbvrb$2s7$1@z-news.wcss.wroc.pl>

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On 22/07/2021 16:37, antispam@math.uni.wroc.pl wrote:
> David Brown <david.brown@hesbynett.no> wrote:
>>
>> The way expressions are interpreted and evaluated is, in most languages,
>> independent of what you do with the results.  (The number of programming
>> languages is so vast that there are bound to be exceptions to almost any
>> rule or generalisation.)
>>
>> If you write :
>>
>>         int x = 4 / 3;
>>         float y = 4 / 3;
>>
>> in most languages, you would not expect the first division to be done as
>> integers and the second to be done as floating point.  You would expect
>> consistency.  It might be consistently integer division, or consistently
>> floating point (and then converted to integer x and floating point y).
>> But you want consistency.
> 
> There are languages that do overloading resolution based on result
> type.  In language that I frequently use both are wrong: division
> on integers produces rational number and can not give back an integer.
> Similarely, division for floats needs floats as arguments while
> 3 and 4 are not floats.  But there are valid expressions in similar
> spirit: they will do different things depending on result type.
> 

Overloading on the operand types is normal :

	float y = (float) 4 / 3;

There are some languages that overload on result type too, but they are
less common.

> Probably the most prominent example of language that has overloading
> on result type is Ada.  However, IIUC in C++ it is possible to
> have eqivalent effect.  Of course, C++ keeps built-in stuff
> reasonably compatible with C, so your examples work as in C.
> But there are interesting examples using user-defiend types.

You can certainly do odd things with C++ to get a related effect, for
your own types.  You can have a type "num" with a division operator that
returns a "deferred_division" type encapsulating the numerator and
denominator, with conversions to float, integer (and rational if you
like) which do the actual division.  There is a name for that pattern,
which I have completely forgotten, and it can be useful in some types of
coding.

> 
> AFAIK the main criterion for "weird" is familiarity: C is widely
> used and several languages ape some aspects of C.  But for
> uninitiated many things in C look weird (including your
> division example).
>

Thread

How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-20 11:15 +0000
  Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-20 13:49 +0100
    Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-20 12:56 +0000
      Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-20 15:36 +0100
        Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-21 01:48 +0000
          Re: How to disambiguate macro? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-20 19:18 -0700
          Re: How to disambiguate macro? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-20 20:27 -0700
            Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-21 04:15 +0000
              Re: How to disambiguate macro? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-21 02:00 -0700
              Re: How to disambiguate macro? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-21 06:02 -0400
          Re: How to disambiguate macro? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-21 06:00 -0400
            Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-21 10:10 +0000
              Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-21 11:30 +0100
              Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-21 13:31 +0200
              Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-21 13:02 +0100
                Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-21 14:20 +0100
                Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-21 15:15 +0100
                Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-21 16:28 +0200
                Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-21 16:20 +0100
                Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-21 17:34 +0100
                Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-21 19:46 +0200
                Re: How to disambiguate macro? Manfred <noname@add.invalid> - 2021-07-21 20:42 +0200
                Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-22 08:37 +0200
                Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-21 20:47 +0100
                Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-22 08:47 +0200
                Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-22 11:31 +0100
                Re: How to disambiguate macro? antispam@math.uni.wroc.pl - 2021-07-22 14:37 +0000
                Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-22 18:15 +0200
                Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-21 21:19 +0100
                Re: How to disambiguate macro? Manfred <noname@add.invalid> - 2021-07-21 15:42 +0200
                Re: How to disambiguate macro? scott@slp53.sl.home (Scott Lurndal) - 2021-07-21 15:39 +0000
              Re: How to disambiguate macro? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-21 09:22 -0700
              Re: How to disambiguate macro? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-21 17:24 -0400
                Re: How to disambiguate macro? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-07-21 16:42 -0700
                Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-22 05:49 +0000
                Re: How to disambiguate macro? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-07-22 19:11 -0400
                Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-22 05:30 +0000
                Re: How to disambiguate macro? scott@slp53.sl.home (Scott Lurndal) - 2021-07-22 14:14 +0000
                Re: How to disambiguate macro? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-22 17:06 +0100
                OT: possessive adjectives (Was: How to disambiguate macro?) Manfred <noname@add.invalid> - 2021-07-22 15:04 +0200
                Re: OT: possessive adjectives Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 13:37 -0700
          Re: How to disambiguate macro? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 13:58 -0700
  Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-20 14:50 +0200
    Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-20 13:19 +0000
      Re: How to disambiguate macro? Bart <bc@freeuk.com> - 2021-07-20 14:40 +0100
        Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-20 21:02 +0200
      Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-20 21:00 +0200
      Re: How to disambiguate macro? David Brown <david.brown@hesbynett.no> - 2021-07-21 08:15 +0200
      Re: How to disambiguate macro? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 23:17 -0700
  Re: How to disambiguate macro? John Forkosh <forkosh@panix.com> - 2021-07-20 12:51 +0000
  Re: How to disambiguate macro? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-07-20 08:47 -0700

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