Re: (0 == foo), rather than (foo == 0)
From: Peter Williams
Date: Thu Mar 11 2004 - 02:38:37 EST
Willy Tarreau wrote:
Hi,
On Wed, Mar 10, 2004 at 06:36:22PM -0800, Linus Torvalds wrote:
And while "0 == foo" may be logically the same thing as "foo == 0", the
fact is, the latter is what people are used to seeing. And by being used
to seeing it, they have an easier time thinking about it.
As a result, using the former just tends to increase peoples confusion by
making code harder to read, which in turn tends to increase the chance of
bugs.
I have a friend who constantly uses it, and his code is unreadable, because
sometimes, a "0 == xxx" becomes "0 <= xxx" or "0 >= xxx" which is difficult
to understand. Thinking that xxx is negative because it's written on the
right side of a >= is complicated. And the worst he does is when he uses
functions :
if (0 < strcmp(a, "xxx")) ...
if (sizeof(t) > read(fd, t, sizeof(t)) ...
I have already helped him track bugs in his programs, and some of them were
just related to this usage, because nobody's brain can understand these
constructions immediately without thinking a bit. So I'm all against this
sort of thing.
One final note. I agree with all the statements of how awkward and
unnatural the back to front boolean expressions look but I had adopted
this technique (for myself) as a means of overcoming design shortcomings
in the C language. I intend to keep doing it in my private code (as
it's saved my bacon a number of times) but will conform to Linus's
standards for any contributions/patches I submit for kernel code (just
as I would conform for any other person's standards if I were to
contribute to their work). In the long run, consistency in a body of
code greatly enhances its readability.
Peace?
Peter
--
Dr Peter Williams, Chief Scientist peterw@xxxxxxxxxx
Aurema Pty Limited Tel:+61 2 9698 2322
PO Box 305, Strawberry Hills NSW 2012, Australia Fax:+61 2 9699 9174
79 Myrtle Street, Chippendale NSW 2008, Australia http://www.aurema.com
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