Re: Libraries using longjmp for error handling

From	Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups	comp.lang.c
Subject	Re: Libraries using longjmp for error handling
Date	2023-09-28 17:35 -0700
Organization	None to speak of
Message-ID	<87edihstna.fsf@nosuchdomain.example.com> (permalink)
References	(2 earlier) <pan$6f4ce$6edf891e$2b5c40c1$f8f989c1@invalid.invalid> <AE3RM.402236$kCld.195109@fx08.ams4> <871qejf62x.fsf@bsb.me.uk> <pan$b83bb$766eb4cb$b79b4acf$fdd8021c@invalid.invalid> <PanRM.9358$Sn81.8479@fx08.iad>

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scott@slp53.sl.home (Scott Lurndal) writes:
> Blue-Maned_Hawk <bluemanedhawk@invalid.invalid> writes:
>>Ben Bacarisse wrote:
>>> Haskell does not always get it right (particularly some of the older
>>> APIs) but the trend is to provide return type rich enough to include
>>> either a correct result or an explanation of the fault.
>>
>>Things like that are pretty much what i was referring to earlier when i
>>referred to making the return type more complex to handle more complex
>>situations.  Obviously, it would have to be done differently in C, since C 
>>doesn't support tagged unions (at least not natively—i know of a couple 
>>libraries that use macro magic to implement them).
>
> In C++, a std::pair<bool, return-type> is used in that context.   If the sizeof
> the return type is 64-bits or less, most modern ABI's will return it in a pair
> of registers.

<OT>
A std::pair<bool, return-type> gives you either a true value and a value
of the return type or a false value and a value of the return type.
There's no indication in the type itself that the second member is
meaningless if the first is false.

std::optional<return-type> is a better fit -- but it isn't available if
you have to deal with pre-C++17 compilers.
</OT>

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */

Thread

Libraries using longjmp for error handling (was: Re: More on NNTP testing) Blue-Maned_Hawk <bluemanedhawk@invalid.invalid> - 2023-09-27 22:52 +0000
  Re: Libraries using longjmp for error handling (was: Re: More on NNTP testing) Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2023-09-28 08:19 +0800
    Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-28 02:18 +0100
      Re: Libraries using longjmp for error handling Blue-Maned_Hawk <bluemanedhawk@invalid.invalid> - 2023-09-28 22:30 +0000
        Re: Libraries using longjmp for error handling scott@slp53.sl.home (Scott Lurndal) - 2023-09-28 22:33 +0000
          Re: Libraries using longjmp for error handling Anton Shepelev <anton.txt@gmail.moc> - 2023-09-29 01:41 +0300
            Re: Libraries using longjmp for error handling scott@slp53.sl.home (Scott Lurndal) - 2023-09-28 23:45 +0000
          Re: Libraries using longjmp for error handling Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-09-28 17:35 -0700
            Re: Libraries using longjmp for error handling David Brown <david.brown@hesbynett.no> - 2023-09-29 16:49 +0200
      Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-28 18:24 -0700
        Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-29 03:19 +0100
          Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-29 07:46 -0700
            Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-29 21:02 +0100
              Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-29 21:56 -0700
                Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-10-01 00:06 +0100
                Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-30 20:35 -0700
                Re: Libraries using longjmp for error handling Anton Shepelev <anton.txt@gmail.moc> - 2023-10-01 14:44 +0300
                Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-10-01 15:45 +0100
                Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-10-01 09:28 -0700
                Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-10-01 20:49 +0100
                Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-10-02 02:31 -0700
                Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-10-02 23:55 +0100
                Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-10-03 05:01 -0700
            Re: Libraries using longjmp for error handling Anton Shepelev <anton.txt@gmail.moc> - 2023-09-29 23:58 +0300
              Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-10-01 02:52 -0700
                Re: Libraries using longjmp for error handling Anton Shepelev <anton.txt@gmail.moc> - 2023-10-01 14:33 +0300
  Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-28 01:48 +0100
  Re: Libraries using longjmp for error handling (was: Re: More on NNTP testing) Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-28 05:11 +0000
    Re: Libraries using longjmp for error handling (was: Re: More on NNTP testing) Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-28 06:26 +0000
  Re: Libraries using longjmp for error handling (was: Re: More on NNTP testing) Anton Shepelev <anton.txt@gmail.moc> - 2023-09-28 16:02 +0300
    Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-28 14:44 +0100
      Re: Libraries using longjmp for error handling Anton Shepelev <anton.txt@gmail.moc> - 2023-09-28 18:31 +0300
        Re: Libraries using longjmp for error handling Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-28 16:43 +0000
          Re: Libraries using longjmp for error handling scott@slp53.sl.home (Scott Lurndal) - 2023-09-28 17:00 +0000
            Re: Libraries using longjmp for error handling Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-28 17:16 +0000
            Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-28 19:38 +0100
          Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-28 16:05 -0700
            Re: Libraries using longjmp for error handling Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-29 00:26 +0000
              Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-28 23:20 -0700
            Re: Libraries using longjmp for error handling Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-09-28 18:31 -0700
              Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-29 03:24 +0100
                Re: Libraries using longjmp for error handling Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-29 03:12 +0000
              Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-28 22:45 -0700
                Re: Libraries using longjmp for error handling Spiros Bousbouras <spibou@gmail.com> - 2023-09-29 12:02 +0000
                Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-29 08:10 -0700
                Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-29 17:03 +0100
                Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-29 10:15 -0700
                Re: Libraries using longjmp for error handling gazelle@shell.xmission.com (Kenny McCormack) - 2023-09-29 17:17 +0000
                Re: Libraries using longjmp for error handling Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-29 18:53 +0000
                Re: Libraries using longjmp for error handling Anton Shepelev <anton.txt@gmail.moc> - 2023-09-29 18:11 +0300
                Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-29 10:20 -0700
                Re: Libraries using longjmp for error handling Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2023-09-29 11:30 -0700
                Re: Libraries using longjmp for error handling Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-29 18:31 +0000
        Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-28 19:27 +0100
          Re: Libraries using longjmp for error handling Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-28 20:24 +0000
            Re: Libraries using longjmp for error handling Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-09-28 22:23 +0100
              Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-28 15:43 -0700
              Re: Libraries using longjmp for error handling Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-28 23:11 +0000
                Re: Libraries using longjmp for error handling Anton Shepelev <anton.txt@gmail.moc> - 2023-09-29 17:23 +0300
                Re: Libraries using longjmp for error handling Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-29 08:19 -0700
        Re: Libraries using longjmp for error handling David Brown <david.brown@hesbynett.no> - 2023-09-28 21:57 +0200
  Re: Libraries using longjmp for error handling Richard Kettlewell <invalid@invalid.invalid> - 2023-09-30 09:37 +0100

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