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Groups > comp.lang.c > #149883
| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Coding style for small if statements |
| Date | 2020-02-09 15:35 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <87zhdrlqns.fsf@bsb.me.uk> (permalink) |
| References | (5 earlier) <r1je7h$5fl$1@dont-email.me> <87k14ym0lg.fsf@bsb.me.uk> <r1mn3m$dtk$1@dont-email.me> <875zggms21.fsf@bsb.me.uk> <r1osb3$4a5$1@dont-email.me> |
David Brown <david.brown@hesbynett.no> writes:
> On 09/02/2020 03:07, Ben Bacarisse wrote:
>> This exchange is, I feel, not very productive. You seem to be
>> attributing to me views I don't have and arguing against those.
>>
>> In particular, you seem to think I don't value "clarity" in code and,
>> secondarily, that I think code is for computers not humans. I don't
>> know how you got that from what I wrote. Maybe I was not clear.
>>
>> Anyway, I'm going to reply to only a couple of very specific points
>> because I am not against writing clear code.
>
> I don't think you gave the impression of being against writing clear
> code, and I am sorry if it looked as though I thought that.
>
> I think merely that we have different opinions as to what comprises
> clear code, and perhaps different emphasis on the benefits of
> particular details of code formatting choices.
>
> And while we both prefer to write clear code (for different measures
>of "clear"), we may also have different levels of dislike of unclear
>code.
>
>
>>
>> David Brown <david.brown@hesbynett.no> writes:
>>
>>> On 08/02/2020 00:36, Ben Bacarisse wrote:
>>>> David Brown <david.brown@hesbynett.no> writes:
>>>>
>>>>> On 07/02/2020 02:26, Ben Bacarisse wrote:
>>>>>> John Bode <jfbode1029@gmail.com> writes:
>>>>>>
>>>>>>> On Wednesday, February 5, 2020 at 5:36:14 PM UTC-6, Ben Bacarisse wrote:
>>>>>>>> John Bode <jfbode1029@gmail.com> writes:
>>>>>>>>
> <snip>
>>>>
>>>
>>> I know which "if" the "else" belonged to. But I don't think the
>>> format of the code matches the semantics of the code, and I think that
>>> is bad style - it risks confusion.
>>
>> What is the confusion that is risked? Do you mean thata there are at
>> least two meanings that could be considered for the original code? If
>> so, what are those? If not, what is the risk you see?
>
> Looking back at the original code (this thread has got a bit too
> long), I don't think I would have trouble understanding the meaning.
> But it requires more mental effort than it should do in order to read
> the code. And the point of the original post is that some people might
> well see two possible meanings of it. Not all people reading C code
> are as experienced as you or I.
This is where it gets so frustrating. Who are these people who can give
that code more than one totally obvious meaning, and why are they even
reading C much less possibly maintaining it? Have you ever met such a
person? Why were they reading C code? If you have come across such a
programmer, what is the other interpretation that they might consider?
I really want to understand other people's perspectives on this because
my imagination fails me here. I think I have a syntax-oriented brain.
Syntax errors (or formatting oddities like the one you show below) just
SCREAM AT ME and I react in an almost visceral way to them.
> Some of the later examples in the thread have had more scope for
> confusion, where it is unclear whether the programmer meant one thing
> and wrote semantically incorrect code, or meant to write what the C
> code says, but did so with unclear formatting.
I'll just note that I am much less interested in the intent of the
author than others seem to be. Of course the code should be clear, and
the formatting and layout should reflect the syntax (it can't really
reflect the intent unless the code is also correct) but I don't read
what I think the author meant, I read what the author wrote.
>> <cut>
>>>>>> What's more, you are suggesting that code errors of this sort frequently
>>>>>> survive long enough for someone like you to see them. Whilst C programs
>>>>>> can have subtle errors that go uncaught for some time, your people
>>>>>> should have a testing regime in place so that basic errors of logic get
>>>>>> caught immediately.
>>>>>
>>>>> Of course it is important to have good test regimes in place - noting
>>>>> again that everyone involved is human and tests are never perfect. In
>>>>> particular, testing can never prove the absence of bugs, but only prove
>>>>> their presence.
>>>>
>>>> But in the case in point there is a bug! People do write silly things
>>>> like putting code next to branch of an if whilst forgetting to add the
>>>> {}s. But the result is code with a bug that will be found in the very
>>>> first test run. This is either a non-issue (as I hope it would be in
>>>> most production environments), or it signals that something else is
>>>> seriously wrong.
>>>
>>> How many programs are written with /complete/ test coverage? I expect
>>> that if you round to the nearest tenth of a percent, the answer is 0%.
>>
>> No wonder the profession is in crisis. So much time posting about {}s
>> and so little about untested code. (I have to take your numbers at face
>> value -- I have no data at all.)
>
> I can't claim any references for the numbers either. I just know
> there is a great deal of code gets released and used without complete
> test coverage. Most of it gets tested reasonably, I expect. But how
> many people who check the result of "malloc" for a null pointer return
> can honestly say they always use fault injection to test the code path
> followed on allocation error? (That is, of course, just one example.)
Yes, and IO errors can be particularly hard. By the way, when I mean
tested I don't necessarily mean automatically tested with a test suite,
but I think programmers should test as much as possible even if that
involves using a debugger to force an error return from a library
function.
Anyway, as I said, I accept your depressing numbers. What is odd, in
the light of them, is how little talk there is here about testing code
compared to the relatively frequent debates about ()s and {}s.
>>> This kind of thing has caused bugs that escaped into the wild - in
>>> code that was reviewed, heavily tested, and used massively in large
>>> numbers of systems.
>>
>> This kind of assertion is unhelpful without details. There's no way to
>> determine what really went wrong and what process or procedure would
>> have prevented it.
>>
>
> A famous example would be the "Apple goto fail" in their SSL/TLS
> code. I assume (perhaps inappropriately) that Apple tested this code,
> and it was certainly commonly used code.
>
> The relevant section of the code was
>
> if ((err = SSLHashSHA1.update(&hashCtx, &serverRandom)) != 0)
> goto fail;
> if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0)
> goto fail;
> goto fail;
> if ((err = SSLHashSHA1.final(&hashCtx, &hashOut)) != 0)
> goto fail;
>
> With a code formatting style that required braces on "if" statements,
> that mistake would have stood out like a sore thumb.
Seriously? That mistake does not stand out like a sore thumb? I mean
that almost literally. Just a glance for a fraction of second and I am
almost in physical pain.
Anyway, if this is an example of what you meant, this code must have
been "heavily tested". Was it? A whole chunk of code has no test
coverage (the function continues, of course) even with no test harness
to simulate errors.
This is a classic example of why goto is considered harmful. The bug
comes from the fact that the fail label (presumably) just returns err.
Every place where you have
label:
<code>;
in a C function you must check (and test) every place from which you can
get here. That's why I hate gotos so much and why I am cautious about
breaks. The pre-conditions for "<code>" are hard to determine.
Of course, no one determines pre- and post-conditions these days and I
accept that that is now a lost art, but in my very limited experience,
I've found more bugs from simple and informal reasoning about code than
I ever found through testing.
--
Ben.
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Coding style for small if statements Anton Shepelev <anton.txt@gmail.com> - 2020-01-31 23:46 +0300
Re: Coding style for small if statements Anton Shepelev <anton.txt@gmail.com> - 2020-01-31 23:54 +0300
Re: Coding style for small if statements Les Cargill <lcargill99@comcast.com> - 2020-01-31 19:13 -0600
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 07:52 -0800
Re: Coding style for small if statements Anton Shepelev <anton.txt@gmail.com> - 2020-02-01 00:06 +0300
Re: Coding style for small if statements mathog <dmathog@gmail.com> - 2020-02-28 10:20 -0800
Re: Coding style for small if statements Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2020-01-31 16:28 -0500
Re: Coding style for small if statements donalhambra@gmail.com - 2020-02-01 04:55 -0800
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-01 17:16 +0000
Re: Coding style for small if statements luser droog <luser.droog@gmail.com> - 2020-02-02 11:03 -0800
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-03 02:20 +0000
Re: Coding style for small if statements Bonita Montero <Bonita.Montero@gmail.com> - 2020-02-03 05:17 +0100
Re: Coding style for small if statements chad <cdalten@gmail.com> - 2020-02-03 04:07 -0800
Re: Coding style for small if statements luser droog <luser.droog@gmail.com> - 2020-02-03 12:59 -0800
Re: Coding style for small if statements chad <cdalten@gmail.com> - 2020-02-03 20:54 -0800
Re: Coding style for small if statements nobody@example.org (Scott) - 2020-02-01 16:44 +0000
Re: Coding style for small if statements already5chosen@yahoo.com - 2020-02-02 04:40 -0800
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-02 15:47 +0100
Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-03 23:56 +0000
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 05:34 -0800
Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-16 16:17 +0000
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 08:28 -0800
Re: Coding style for small if statements skybuck2000@hotmail.com - 2020-02-03 21:52 -0800
Re: Coding style for small if statements skybuck2000@hotmail.com - 2020-02-03 22:07 -0800
Re: Coding style for small if statements skybuck2000@hotmail.com - 2020-02-03 22:22 -0800
Re: Coding style for small if statements skybuck2000@hotmail.com - 2020-02-03 22:25 -0800
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-05 02:35 +0000
Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-04 20:20 -0800
Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-05 01:04 -0500
Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-05 01:05 -0500
Re: Coding style for small if statements John Bode <jfbode1029@gmail.com> - 2020-02-05 12:50 -0800
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-05 23:36 +0000
Re: Coding style for small if statements John Bode <jfbode1029@gmail.com> - 2020-02-06 15:01 -0800
Re: Coding style for small if statements Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-02-06 15:43 -0800
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-07 11:02 +0100
Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-07 15:24 +0000
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-07 23:03 +0000
Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-07 23:59 +0000
Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-08 00:16 +0000
Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-08 02:26 +0000
Re: Coding style for small if statements Les Cargill <lcargill99@comcast.com> - 2020-02-08 17:07 -0600
Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-08 23:17 +0000
Re: Coding style for small if statements Les Cargill <lcargill99@comcast.com> - 2020-02-08 18:32 -0600
Re: Coding style for small if statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-02-09 09:32 -0800
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 07:10 -0800
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-07 01:26 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-07 11:30 +0100
Re: Coding style for small if statements chad <cdalten@gmail.com> - 2020-02-07 05:36 -0800
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-07 23:36 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-08 17:20 +0100
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 02:07 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-09 13:01 +0100
Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-09 13:26 +0000
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 15:53 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-09 17:03 +0100
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 15:35 +0000
Re: Coding style for small if statements Manfred <noname@add.invalid> - 2020-02-09 18:07 +0100
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 21:17 +0000
Pre- and post- conditions (was Re: Coding style for small if statements) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-11 07:19 +0000
Re: Pre- and post- conditions (was Re: Coding style for small if statements) Öö Tiib <ootiib@hot.ee> - 2020-02-10 23:40 -0800
Re: Pre- and post- conditions (was Re: Coding style for small if statements) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-12 12:24 +0000
Re: Pre- and post- conditions (was Re: Coding style for small if statements) Bart <bc@freeuk.com> - 2020-02-11 11:30 +0000
Re: Pre- and post- conditions (was Re: Coding style for small if statements) Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2020-02-11 09:41 -0700
Re: Pre- and post- conditions (was Re: Coding style for small if statements) James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-12 08:12 -0500
Re: Pre- and post- conditions (was Re: Coding style for small if statements) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-14 21:18 +0000
Re: Pre- and post- conditions (was Re: Coding style for small if statements) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 00:01 -0800
Re: Pre- and post- conditions (was Re: Coding style for small if statements) James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-22 05:22 -0800
Re: Pre- and post- conditions (was Re: Coding style for small if statements) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 07:57 -0700
Re: Pre- and post- conditions (was Re: Coding style for small if statements) James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-02 08:28 -0700
Re: Pre- and post- conditions (was Re: Coding style for small if statements) jadill33@gmail.com - 2020-02-12 07:56 -0800
Re: Pre- and post- conditions (was Re: Coding style for small if statements) chad <cdalten@gmail.com> - 2020-02-12 08:57 -0800
Re: Pre- and post- conditions (was Re: Coding style for small if statements) Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-14 21:31 +0000
Re: Pre- and post- conditions (was Re: Coding style for small if statements) jadill33@gmail.com - 2020-02-14 14:10 -0800
Re: Pre- and post- conditions (was Re: Coding style for small if statements) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-15 03:06 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-09 19:45 +0100
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 21:50 +0000
Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-09 22:51 +0000
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 01:39 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-10 09:55 +0100
Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-10 11:07 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-10 12:48 +0100
Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-10 13:13 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-10 15:15 +0100
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 15:46 +0000
Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-09 18:18 -0800
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-10 09:12 +0100
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 14:51 +0000
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 16:19 +0000
Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-09 21:00 +0000
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 21:29 +0000
Re: Coding style for small if statements luser droog <luser.droog@gmail.com> - 2020-02-09 17:14 -0800
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-09 21:15 +0000
Re: Coding style for small if statements James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-02-09 18:43 -0500
Re: Coding style for small if statements Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-02-10 01:25 +0000
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 01:19 -0800
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 05:43 -0800
Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-16 14:01 +0000
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-22 08:34 -0800
Re: Coding style for small if statements Guillaume <message@bottle.org> - 2020-02-07 15:25 +0100
Re: Coding style for small if statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-02-07 07:22 -0800
Re: Coding style for small if statements Anton Shepelev <anton.txt@g{oogle}mail.com> - 2020-02-14 15:21 +0300
Re: Coding style for small if statements Bart <bc@freeuk.com> - 2020-02-14 13:35 +0000
Re: Coding style for small if statements Guillaume <message@bottle.org> - 2020-02-14 14:43 +0100
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-15 12:08 +0100
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-20 10:10 -0800
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-20 19:58 +0100
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 05:55 -0800
Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-07 15:26 +0000
Re: Coding style for small if statements luser droog <luser.droog@gmail.com> - 2020-02-07 17:47 -0800
Re: Coding style for small if statements jadill33@gmail.com - 2020-02-10 07:09 -0800
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-16 06:30 -0800
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-16 16:14 +0100
Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-16 16:40 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-16 17:48 +0100
Re: Coding style for small if statements Robert Wessel <robertwessel2@yahoo.com> - 2020-02-16 17:14 -0600
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-03-30 00:27 -0700
Re: Coding style for small if statements Ike Naar <ike@sdf.lonestar.org> - 2020-02-16 18:39 +0000
Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-16 20:37 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-02-17 09:09 +0100
Re: Coding style for small if statements Öö Tiib <ootiib@hot.ee> - 2020-02-17 05:32 -0800
Re: Coding style for small if statements scott@slp53.sl.home (Scott Lurndal) - 2020-02-17 18:07 +0000
Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-02-17 23:48 +0000
Re: Coding style for small if statements Richard Damon <Richard@Damon-Family.org> - 2020-02-17 20:40 -0500
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-23 10:14 -0800
Re: Coding style for small if statements Ike Naar <ike@iceland.freeshell.org> - 2020-02-23 20:16 +0000
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-03-29 18:56 -0700
Re: Coding style for small if statements Ike Naar <ike@sdf.lonestar.org> - 2020-03-30 06:07 +0000
Re: Coding style for small if statements Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-03-30 06:45 +0000
Re: Coding style for small if statements David Brown <david.brown@hesbynett.no> - 2020-03-30 10:50 +0200
Re: Coding style for small if statements gazelle@shell.xmission.com (Kenny McCormack) - 2020-03-30 13:04 +0000
Re: Coding style for small if statements Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-03-30 06:17 -0700
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-04 14:09 -0700
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-18 02:09 -0800
Re: Coding style for small if statements Jens Stuckelberger <Jens_Stuckelberger@nowhere.net> - 2020-02-10 01:47 +0000
Re: Coding style for small if statements Bonita Montero <Bonita.Montero@gmail.com> - 2020-02-12 17:54 +0100
Re: Coding style for small if statements Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-02-20 07:18 -0800
Re: Coding style for small if statements fir <profesor.fir@gmail.com> - 2020-02-29 03:30 -0800
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