svn commit: r368714 - head/lib/libc/string

[Ian Lepore]

On Thu, 2020-12-17 at 18:22 +0200, Konstantin Belousov wrote:
> On Thu, Dec 17, 2020 at 01:01:01PM +0000, Jessica Clarke wrote:
> > On 17 Dec 2020, at 12:53, Konstantin Belousov <kostikbel at gmail.com>
> > wrote:
> > > 
> > > On Thu, Dec 17, 2020 at 12:41:47PM +0000, Mateusz Piotrowski
> > > wrote:
> > > > Author: 0mp (doc,ports committer)
> > > > Date: Thu Dec 17 12:41:47 2020
> > > > New Revision: 368714
> > > > URL: https://svnweb.freebsd.org/changeset/base/368714
> > > > 
> > > > Log:
> > > >  strerror.3: Add an example for perror()
> > > > 
> > > >  This is a nice and quick reference.
> > > > 
> > > >  Reviewed by:	jilles, yuripv
> > > >  MFC after:	2 weeks
> > > >  Differential Revision:	https://reviews.freebsd.org/D27623
> > > > 
> > > > Modified:
> > > >  head/lib/libc/string/strerror.3
> > > > 
> > > > Modified: head/lib/libc/string/strerror.3
> > > > ===============================================================
> > > > ===============
> > > > --- head/lib/libc/string/strerror.3	Thu Dec 17 03:42:54
> > > > 2020	(r368713)
> > > > +++ head/lib/libc/string/strerror.3	Thu Dec 17 12:41:47
> > > > 2020	(r368714)
> > > > @@ -32,7 +32,7 @@
> > > > .\"     @(#)strerror.3	8.1 (Berkeley) 6/9/93
> > > > .\" $FreeBSD$
> > > > .\"
> > > > -.Dd December 7, 2020
> > > > +.Dd December 17, 2020
> > > > .Dt STRERROR 3
> > > > .Os
> > > > .Sh NAME
> > > > @@ -170,6 +170,31 @@ The use of these variables is deprecated;
> > > > or
> > > > .Fn strerror_r
> > > > should be used instead.
> > > > +.Sh EXAMPLES
> > > > +The following example shows how to use
> > > > +.Fn perror
> > > > +to report an error.
> > > > +.Bd -literal -offset 2n
> > > > +#include <fcntl.h>
> > > > +#include <stdio.h>
> > > > +#include <stdlib.h>
> > > > +
> > > > +int
> > > > +main(void)
> > > > +{
> > > > +	int fd;
> > > > +
> > > > +	if ((fd = open("/nonexistent", O_RDONLY)) == -1) {
> > > > +		perror("open()");
> > > > +		exit(1);
> > > > +	}
> > > > +        printf("File descriptor: %d\en", fd);
> > > 
> > > This lines is indented with spaces, while other lines have tabs.
> > > 
> > > > +	return (0);
> > > 
> > > return (0) is redundand.
> > 
> > It's not required as per the standard, but omitting it is needlessly
> > obfuscating it and bad practice. C lets you do a whole load of things
> > that are a bad idea, and whilst this one is harmless, it is nonetheless
> > confusing to anyone who is not intimately acquainted quirks like this
> > special case in the standard.
> 
> Why it is bad practice ?
> 
> C is a small language, and while knowing some quirks (like this one)
> seems to be optional, others are not. And worse, that other quirks are
> essential for writing correct code at all. Consequence is that ignoring
> details indicates insufficient knowledge of the fundamentals and lowers
> the trust in the provided suggestion.

I completely disagree.  Writing example code where you fail to return a
value and just fall out the bottom of some function that declares it
returns an int is just Bad Code.  Using some obscure quirk of the
language as justification for that bad code doesn't help the situation
at all.

How obscure is this quirk?  I've been writing C code since 1983,
including having released a freeware compiler (pre-gcc days) and
working on a commercial C compiler.  I used to moderate the c_language
conference on BIX (back when that was a thing).  I make my living
writing C and C++ code every day.  And yet, I had completely forgotten
about this quirk.

Example code shouldn't be used to establish how much more clever you
are than the reader, it should be as easy to understand as possible.

-- Ian