On Wed, 20 Apr 2016, John Baldwin wrote:
On Wednesday, April 20, 2016 01:06:38 PM Bruce Evans wrote:
On Wed, 20 Apr 2016, Marcelo Araujo wrote:
2016-04-20 0:16 GMT+08:00 John Baldwin <j...@freebsd.org>:
On Tuesday, April 19, 2016 04:46:13 AM Marcelo Araujo wrote:
Author: araujo
Date: Tue Apr 19 04:46:13 2016
New Revision: 298247
URL: https://svnweb.freebsd.org/changeset/base/298247
Log:
Remove redundant parenthesis.
Submitted by: pfg
MFC after: 2 weeks.
I don't realling like churnging to the nonstandard nitems(). Use
of the nonstandard <sys/param.h> is bad enough.
I think it's not that bad from a readability standpoint. Other languages
have fairly concise syntax for 'for-each' loops and this provides a
closer variant of that for statically sized arrays. TAILQ_FOREACH() is
still nicer of course. One could imagine doing some sort of
ARRAY_FOREACH() that was:
Ugh, I really realling (sic) don't like the FOREACH macros. The FOREACH
macros add syntactic salt. The queue macros were bad enough before they
had FOREACH. Arrays don't start with such nastiness.
#define ARRAY_FOREACH(p, array) \
for (size_t __i = 0, (p) = &(array)[0]; __i < nitems((array)); __i++,
(p)++)
This only works in the not very usual case of a simple loop from the start
to the end. Even the name EACH becomes wrong if the range is anything else.
For full nastiness, add a few hundred FORFOO macros to handle multi-
dimensional arrays with different access methods, array slices, sentinels
and other terminating conditions, etc.
Perhaps better is this:
#define ARRAY_FOREACH(p, array) \
for ((p) = &(array)[0]; (p) < &(array)[nitems((array))]; (p)++)
(No need for __i)
But hiding the indexes forces the old C programming idiom of using
pointers for everything. A mere few hundred FORFOO macros won't do.
For just 1-dimensional FOREACH, you need 3 versions to expose p, i or
both p and i.
Churnging too much (also remove excessive parentheses and braces) gives:
size_t i; /* XXX: I don't like unsigned types, but... */
for (i = 0; i < nitems(part_types); i++)
if (part_types[i].type == type & 0x7f)
return (part_types[i].name);
return ("unknown");
This would work for me (unless folks actually like the ARRAY_FOREACH()
idea).
Once a loop is simple enough, it is easy to see that it really is simple
without an ARRAY_FOREACH() macros that hides its details. Actually, it
is not so simple since it has a special terminating condition. It only
handles EACH (every) element in unusual cases.
Bruce
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