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On 7/29/2010 8:34 PM, Shao Miller wrote:
> #define MAXARGS 10
> typedef unsigned int zlink_args[MAXARGS];
>
> int zlink(int(int, ...), int, unsigned int *);
> int zlink(int bar(int, ...), int flags, unsigned int *list) {
> return 12;
> }
>
> unsigned int *buildlist(zlink_args list, ...) {
> /* ... */
> return list;
> }
>
> int foo(int bar, ...) {
> return 5;
> }
>
> #define LINKX(routine,flags,list, ...) \
> (zlink((routine),(flags),buildlist((list), __VA_ARGS__)))
>
> int main(void) {
> zlink_args mylist;
> int w, x, y, z;
>
> w = x = y = z = 10;
> return LINKX(foo, (1<< 3)& (1<< 4), mylist, w, x, y, z);
> }

I'll probably do something like this, although I want to hide the
zlink_args stuff in the macro. Thanks.

On Jul 30, 11:39*am, Ann O'Nymous <nob...@nowhere.com> wrote:
> I'll probably do something like this, although I want to hide the
> zlink_args stuff in the macro. *Thanks.
Could you at all be interested in sharing a bit more about your
requirement for building the arguments into an array that's all inside
the macro?

For example, why use a macro at all? You could use a function that
allocates the array, populates it from arguments, then calls 'zlink'
and returns that call's result.

Also, consider a loop where we don't pass 'mylist':

enum { lim = 50 };
int i, rc, w, x, y, z;

w = x = y = z = 0;
for (i = 0; i < lim; i++) {
rc = LINKX(foo, (1 << 3) & (1 << 4), w, x, y, z);
if (rc) {
/* ... */
}
}

If you use Ben's suggestion of C99 compound literals within your
'LINKX' macro, you get nameless objects with automatic storage
duration. When does their lifetime end? If it's the 'for' {} body,
then what's to prevent allocating 50 of them above, as per 'lim'?
That might get expensive.

Are you trying to make minimal changes to someone else's code? Are
you using 'setjmp()' and friends and have concerns about allocating
something like 'mylist' in a function's body? Or maybe you don't wish
to add such an allocation to every function using the 'LINKX' macro?