Date: Fri, 1 Jun 2012 13:16:58 -0400 From: John Baldwin <jhb@freebsd.org> To: Eitan Adler <eadler@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Bruce Evans <brde@optusnet.com.au> Subject: Re: svn commit: r236377 - head/sys/dev/vxge/vxgehal Message-ID: <201206011316.58330.jhb@freebsd.org> In-Reply-To: <CAF6rxgnTFVBNOewiPXNvHyt3YamWsa6YZDPFtM4-uumUD6Eqdg@mail.gmail.com> References: <201206010423.q514NKtf083043@svn.freebsd.org> <201206011024.49122.jhb@freebsd.org> <CAF6rxgnTFVBNOewiPXNvHyt3YamWsa6YZDPFtM4-uumUD6Eqdg@mail.gmail.com>
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On Friday, June 01, 2012 12:39:48 pm Eitan Adler wrote:
> On 1 June 2012 07:24, John Baldwin <jhb@freebsd.org> wrote:
> > This is why I personally loathe assignment side effects in boolean expressions
> > for control flow. I tend to write this sort of thing instead as:
> >
> > channel->dtr_arr[dtr_index].dtr = dtrh;
> > if (dtrh != NULL) {
>
> Same here. I was told to use the assignment is style(9) by multiple
> people though. If it really is, I wish it would change.
style(9) doesn't make a clear statement either way, but it has contradicting
examples.
First:
while ((ch = getopt(argc, argv, "abNn:")) != -1)
(and this one I use all the time myself as that is the common idiom for
getopt())
Second:
error = function(a1, a2);
if (error != 0)
exit(error);
Also, style(9) tends to frown on assignments that are side-effects in other
places, for example:
Be careful to not obfuscate the code by initializing variables in the
declarations. Use this feature only thoughtfully. DO NOT use function
calls in initializers.
struct foo one, *two;
double three;
int *four, five;
char *six, seven, eight, nine, ten, eleven, twelve;
four = myfunction();
Some newer changes added at the end do use assignment side-effects while
demonstrating other rules (the !p example and err(3) and warn(3) examples,
this last I find particularly obfuscated and painful to read).
Note that I do not consider this to be an assignment side effect:
if (ioctl(...) < 0)
err(1, "ioctl");
That is, I don't write that out as:
i = ioctl(...);
if (i < 0)
However, I do split it out if the return value is used for more than error
checking, e.g.:
fd = open(...);
if (fd < 0)
err(1, "open");
--
John Baldwin
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