On Tue, Jun 14, 2016 at 01:45:10PM +0930, Paul 'Rusty' Russell wrote: > Dan Good <d...@dancancode.com> writes: > > Hi David, > > > > I'm back home in front of a real keyboard, and want to follow up with you > > about your patches. I must admit that my usual practice is to use NULL, > > and not 0. Around the time I wrote altstack I had recently read Jen > > Gustedt's book, Modern C. In it, he makes the point that NULL hides more > > than it clarifies (see section 11.7). > > (I don't really care: your code, your style). But... > > He is so horrifically wrong, it's amazing. > > Section 7.17 is loosened from ANSI C which said NULL was 0, presumably > to *allow* compilers to avoid the varargs issue. A compiler *could* do > insane shit to make that problem even worse, but you would never use > such a compiler. There are other legal-but-insane things a compiler can > do, too, and the answer is the same; real code won't work, nobody else > cares. > > OTOH, using 0 in place of NULL makes for much more potential type order > confusion. Not to mention confusing every damn C programmer on the > planet.
Yeah. I can kind of see the hint of a good idea in those articles,
but on balance they're really not convincing. Basically, as Rusty
says, matching the conventions of the huge bulk of existing C code
outweighs the value of working with a compiler/library that has gone
out of its way to implement this stupidly.
> Note, I also assume NULL is all zero-bits,
I try to avoid that one, although I can't be sure I always have - I'm
not sure, but I think one of the s390 variants might break this.
> that size_t can hold a
> ptrdiff_t,
Dunno if I've assumed that much.
> and that a pointer to a function which takes a type *
> argument can be cast and called as a function which takes a void *.
Yeah, I've used that.
> If someone ports CCAN to a platform where those are not true, I'd be
> fascinated...
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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