Re: (0 == foo), rather than (foo == 0)

[Peter Williams <peterw@aurema.com>]

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@aurema.com
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