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Re: c99 and the lack of warnings when int operations are applied to a bool

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Rui Maciel <rui.maciel@gmail.com> writes:
> James Kuyper wrote:
>>>"I'll grant ..."  (Is there an echo in here?)
>>>
>>>The question that burns in my feeble brain is: "Why?"  What is
>>> the benefit that a "No arithmetic on booleans" rule would bring?
>> 
>> It makes syntax errors out of constructs that are conceptually
>> meaningless, forcing the use of alternative constructs that say more
>> precisely what is actually going on. As such, it makes it easier to
>> detect erroneous constructs.
>> 
>> ...
>>>If you're looking for a language with seat belts, training
>>> wheels, airbags, and padded walls, C shouldn't be your first
>>> choice, and restrictions on arithmetic wouldn't change matters.
>> 
>> A C-like language with few more barriers between conceptually distinct
>> things like numbers, characters, and bools than C has, would make it
>> slightly easier to avoid writing nonsense. Those barriers wouldn't cause
>> the loss of any truly valuable characteristic of C.
>
> I don't believe those barriers are needed for one reason alone: if you do 
> want barriers, you are free to put them up yourself.  Just wrap any 
> primitive data type with a struct and write your code around them as you see 
> fit.
>
> <example>
> rui@Kubuntu:tmp$ cat example.c 
> typedef struct Boolean
> {
>         int value;
> } boolean_t;
>
>
> int main(void)
> {
>         boolean_t b;
>         int number = b*3;
>
>         return 0;
> }
> rui@Kubuntu:tmp$ gcc example.c 
> example.c: In function ‘main’:
> example.c:10:16: error: invalid operands to binary * (have ‘boolean_t’ and 
> ‘int’)
> </example>

The cost of those barriers is massive inconvenience, and the compiler
can enforce restrictions for you only in some cases.

    boolean_t b;
    int number;
    if (b) { ... }       /* error */
    if (b.value) { ... } /* ok */
    if (num) { ... }     /* error not caught by compiler */

    boolean_t x = ...;
    boolean_t y = ...;
    boolean_t x_or_y = (boolean_t){ x.value || y.value };

The C language just doesn't have the ability to define a distinct
boolean type that works the way some of us might like.

(If you don't think having such a type is worthwhile in the first place,
then the disadvantages are irrelevant.)

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
    Will write code for food.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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c99 and the lack of warnings when int operations are applied to a bool mathog <dmathog@gmail.com> - 2012-03-23 08:40 -0700
  Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-03-23 12:07 -0400
  Re: c99 and the lack of warnings when int operations are applied to a bool jacob navia <jacob@spamsink.net> - 2012-03-23 21:45 +0100
    Re: c99 and the lack of warnings when int operations are applied to a bool Robert Wessel <robertwessel2@yahoo.com> - 2012-03-23 17:17 -0500
      Re: c99 and the lack of warnings when int operations are applied to a bool jacob navia <jacob@spamsink.net> - 2012-03-23 23:29 +0100
        Re: c99 and the lack of warnings when int operations are applied   to a bool Ian Collins <ian-news@hotmail.com> - 2012-03-24 11:48 +1300
          Re: c99 and the lack of warnings when int operations are applied   to a bool jacob navia <jacob@spamsink.net> - 2012-03-24 23:47 +0100
            Re: c99 and the lack of warnings when int operations are applied   to a bool Willem <willem@toad.stack.nl> - 2012-03-25 09:05 +0000
              Re: c99 and the lack of warnings when int operations are applied   to a bool "BartC" <bc@freeuk.com> - 2012-03-25 11:30 +0100
                Re: c99 and the lack of warnings when int operations are applied   to a bool Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-25 21:05 +0100
                Re: c99 and the lack of warnings when int operations are applied   to a bool Lowell Gilbert <lgusenet@be-well.ilk.org> - 2012-03-25 16:15 -0400
                Re: c99 and the lack of warnings when int operations are applied   to a bool Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-25 22:14 +0100
                Re: c99 and the lack of warnings when int operations are applied   to a bool James Kuyper <jameskuyper@verizon.net> - 2012-03-25 23:46 -0400
                Re: c99 and the lack of warnings when int operations are applied to a bool Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-26 12:05 +0100
                Re: c99 and the lack of warnings when int operations are applied to a bool Lowell Gilbert <lgusenet@be-well.ilk.org> - 2012-03-26 15:22 -0400
              Re: c99 and the lack of warnings when int operations are applied to a bool Gareth Owen <gwowen@gmail.com> - 2012-03-25 11:44 +0100
                Re: c99 and the lack of warnings when int operations are applied to a bool Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-25 13:06 +0100
            Re: c99 and the lack of warnings when int operations are applied to a bool Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-27 11:12 -0700
        Re: c99 and the lack of warnings when int operations are applied to a bool Robert Wessel <robertwessel2@yahoo.com> - 2012-03-24 01:15 -0500
          Re: c99 and the lack of warnings when int operations are applied to a bool jacob navia <jacob@spamsink.net> - 2012-03-24 23:29 +0100
    Re: c99 and the lack of warnings when int operations are applied to a bool mathog <dmathog@gmail.com> - 2012-03-27 09:53 -0700
      Re: c99 and the lack of warnings when int operations are applied to a bool Keith Thompson <kst-u@mib.org> - 2012-03-27 11:07 -0700
      Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-03-27 14:16 -0400
      Re: c99 and the lack of warnings when int operations are applied to a bool Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-26 07:57 -0400
        Re: c99 and the lack of warnings when int operations are applied to a bool jacob navia <jacob@spamsink.net> - 2012-04-26 14:08 +0200
        Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-26 09:09 -0400
          Re: c99 and the lack of warnings when int operations are applied to a bool Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-26 21:29 -0400
            Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-26 21:58 -0400
              Re: c99 and the lack of warnings when int operations are applied to a bool Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-26 22:32 -0400
                Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-27 06:31 -0400
                Re: c99 and the lack of warnings when int operations are applied to a bool Lanarcam <lanarcam1@yahoo.fr> - 2012-04-27 19:26 +0200
                Re: c99 and the lack of warnings when int operations are applied to a bool Keith Thompson <kst-u@mib.org> - 2012-04-27 11:28 -0700
                Re: c99 and the lack of warnings when int operations are applied to a bool Lanarcam <lanarcam1@yahoo.fr> - 2012-04-27 20:51 +0200
                Re: c99 and the lack of warnings when int operations are applied to a bool ImpalerCore <jadill33@gmail.com> - 2012-04-27 12:17 -0700
                Re: c99 and the lack of warnings when int operations are applied to a bool Jens Gustedt <jens.gustedt@loria.fr> - 2012-04-28 09:17 +0200
                Re: c99 and the lack of warnings when int operations are applied to a bool Keith Thompson <kst-u@mib.org> - 2012-04-28 13:26 -0700
                Re: c99 and the lack of warnings when int operations are applied to a bool Willem <willem@toad.stack.nl> - 2012-04-27 18:11 +0000
                Re: c99 and the lack of warnings when int operations are applied to a bool ImpalerCore <jadill33@gmail.com> - 2012-04-27 12:05 -0700
                Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-27 15:32 -0400
                Re: c99 and the lack of warnings when int operations are applied to a bool Willem <willem@toad.stack.nl> - 2012-04-27 20:16 +0000
                Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-27 16:45 -0400
                Re: c99 and the lack of warnings when int operations are applied to a bool Rui Maciel <rui.maciel@gmail.com> - 2012-04-27 21:26 +0100
                Re: c99 and the lack of warnings when int operations are applied to a bool Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-27 21:18 -0400
                Re: c99 and the lack of warnings when int operations are applied to a bool Rui Maciel <rui.maciel@gmail.com> - 2012-04-27 21:33 +0100
                Re: c99 and the lack of warnings when int operations are applied to a bool Keith Thompson <kst-u@mib.org> - 2012-04-27 15:36 -0700
                Re: c99 and the lack of warnings when int operations are applied to a bool ImpalerCore <jadill33@gmail.com> - 2012-04-27 08:31 -0700

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