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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Synthetic 'unless' keyword |
| Date | 2016-08-04 08:52 -0700 |
| Organization | None to speak of |
| Message-ID | <lnlh0c1qh2.fsf@kst-u.example.com> (permalink) |
| References | <e0gh38F2552U1@mid.uni-berlin.de> |
jt@toerring.de (Jens Thoms Toerring) writes:
> everyone uses 'if' probably hundreds of times a day.
> But in some situations I'd feel that being able to use
> 'unless' instead, as in the trivial example
>
> unless (argc > 1) {
> fprintf(stderr, "Missing argument(s)\n");
> return EXIT_FAILURE;
> }
>
> might contribute to the readability of the code. Now,
> 'unless' isn't a C keyword (as it is in some other
> languages, e.g. Perl) but it seems easy to use a
> define like this
>
> #define unless(expr) if (!(expr))
>
> What possibly could go wrong (except that 'unless' may
> be used as a variable name somewhere and that editors
> with syntax highlighting won't recognize it)? Or would
> it be to "alien" to most C programmers?
In my opinion, adding an `unless` keyword to C wouldn't be harmful, but
it wouldn't be useful enough to justify the change. It would also add
new opportunities for the IOCCC:
unless (! (x != y)) ...
Perl has `unless`, and I write a lot of Perl code. I hardly ever use
`unless` -- and when I do always in the postfix form:
do_this() unless <some_condition>;
One drawback of the `if (!expr)` form is that `!` is a single
character that can sometimes be easy to miss. Adding a space:
`if (! expr)` helps a bit. One nice thing about Perl is that you can
write `not` rather than `!`. You can do the same in C with `#include
<iso646.h>`, but that's unfamiliar enough that I don't use it myself.
(I make no claim that I'm entirely consistent.0
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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Synthetic 'unless' keyword jt@toerring.de (Jens Thoms Toerring) - 2016-08-04 09:44 +0000
Re: Synthetic 'unless' keyword David Brown <david.brown@hesbynett.no> - 2016-08-04 12:21 +0200
Re: Synthetic 'unless' keyword Mark Storkamp <mstorkamp@yahoo.com> - 2016-08-04 07:01 -0500
Re: Synthetic 'unless' keyword bert <bert.hutchings@btinternet.com> - 2016-08-04 05:42 -0700
Re: Synthetic 'unless' keyword Keith Thompson <kst-u@mib.org> - 2016-08-04 08:45 -0700
Re: Synthetic 'unless' keyword Philip Lantz <prl@canterey.us> - 2016-08-04 21:55 -0700
Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-05 10:08 +0100
Re: Synthetic 'unless' keyword Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-05 01:17 -0700
Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-05 10:01 +0100
Re: Synthetic 'unless' keyword Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-05 04:34 -0700
Re: Synthetic 'unless' keyword Mark Storkamp <mstorkamp@yahoo.com> - 2016-08-05 09:37 -0500
Re: Synthetic 'unless' keyword Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-08-06 02:28 -0700
Re: Synthetic 'unless' keyword jt@toerring.de (Jens Thoms Toerring) - 2016-08-04 13:38 +0000
Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-04 15:04 +0100
Re: Synthetic 'unless' keyword mark.bluemel@gmail.com - 2016-08-04 07:06 -0700
Re: Synthetic 'unless' keyword Keith Thompson <kst-u@mib.org> - 2016-08-04 08:52 -0700
Re: Synthetic 'unless' keyword supercat@casperkitty.com - 2016-08-04 09:45 -0700
Re: Synthetic 'unless' keyword Keith Thompson <kst-u@mib.org> - 2016-08-04 10:23 -0700
Re: Synthetic 'unless' keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-04 19:39 +0100
Re: Synthetic 'unless' keyword supercat@casperkitty.com - 2016-08-04 12:02 -0700
Re: Synthetic 'unless' keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-04 20:33 +0100
Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-04 20:42 +0100
Re: Synthetic 'unless' keyword David Brown <david.brown@hesbynett.no> - 2016-08-05 13:14 +0200
Re: Synthetic 'unless' keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-05 12:41 +0100
Re: Synthetic 'unless' keyword mark.bluemel@gmail.com - 2016-08-05 00:53 -0700
Re: Synthetic 'unless' keyword Jerry Stuckle <jstucklex@attglobal.net> - 2016-08-04 16:43 -0400
Re: Synthetic 'unless' keyword David Brown <david.brown@hesbynett.no> - 2016-08-05 13:16 +0200
Re: Synthetic 'unless' keyword jt@toerring.de (Jens Thoms Toerring) - 2016-08-04 23:16 +0000
Re: Synthetic 'unless' keyword Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-05 00:35 +0100
Re: Synthetic 'unless' keyword Tim Rentsch <txr@alumni.caltech.edu> - 2016-08-04 20:13 -0700
Re: Synthetic 'unless' keyword Tim Rentsch <txr@alumni.caltech.edu> - 2016-08-05 04:57 -0700
Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-05 13:15 +0100
Re: Synthetic 'unless' keyword Tim Rentsch <txr@alumni.caltech.edu> - 2016-08-18 08:11 -0700
Re: Synthetic 'unless' keyword BartC <bc@freeuk.com> - 2016-08-18 16:36 +0100
Re: Synthetic 'unless' keyword supercat@casperkitty.com - 2016-08-18 10:20 -0700
Re: Synthetic 'unless' keyword Paul N <gw7rib@aol.com> - 2016-08-07 12:56 -0700
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