On Wed, 20 Apr 2016, Conrad Meyer wrote:
On Wed, Apr 20, 2016 at 7:33 AM, Pedro Giffuni <p...@freebsd.org> wrote:
One of the things I dislike is that most of the macros are in
lowercase. Lowercase would make sense if these were inline functions
but inline functions have disadvantages for these use cases.
OTOH, if they were uppercase, they would not be very easy on the eyes,
which is the current advantage.
Lower case is correct if nitems is a safe macro. I think it is safe,
because its parameter must be an array and an expression with side
effects can't be an array.
You bring up a good point. Obviously nitems() can't be an inline
function, but roundup2() and friends could. Is there any reason not
to change them over to inline functions?
1. Namespace pollution. Adding nitems() to sys/param.h already broke
anything using that name.
2. roundup2() and friends can't be inline functions without unportable
complications to make them type-generic. No one ever did this for
the more important imin() family of inline functions. 4.4BSD removed
the MAX() and MIN() macros in the kernel to enforce use of the imin()
family, but this gave type errors and was routed around by restoring
the macros, first in scattered places and then back in sys/param.h.
2-arg type-generic functions are especially difficult since they have
N^2 combinations where N is approximately the number of types in
inttypes.h. There are 8 basic types just for 8/16/32/64 bits signed
and unsigned. For compaibility, the result type must be the same as
what the macro gives.
Bruce
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