[GRASS-dev] [GRASS-SVN] r60703 - in grass/trunk: display/d.vect general/g.gisenv gui/wxpython/animation lib/python/temporal raster/r.colors raster/r.external raster/r.in.bin raster/r.mapcalc raster/r.neighbors raster/r.out.bin raster/r.quant raster/r.resamp.filter raster/r.series raster/r.series.accumulate raster/r.series.interp raster/r.stats.quantile vector/v.colors vector/v.external.out

[Huidae Cho]

Right, G_option_exclusive(void *first, ...) should work.


On Wed, Jun 11, 2014 at 6:43 AM, Glynn Clements <glynn at gclements.plus.com>
wrote:

>
> Huidae Cho wrote:
>
> > Maybe, we can use variadic macros in C99 to remove the first name
> argument.
>
> GRASS doesn't require C99. In general, we try to keep the hard
> dependencies to a bare minimium, particularly in core functionality
> such as libgis.
>
> In any case, the <stdarg.h> requirement for an explicit first argument
> isn't a significant problem. The functions would never be called with
> less than two arguments.
>
> In the worst case, it complicates the implementation slightly, as we
> can't simply iterate over all of the arguments using va_arg(), but
> have to treat the explicit argument separately. That can be handled
> like:
>
>         void G_option_exclusive(void *first, ...)
>         {
>             void *opt = first;
>             va_start(ap, first);
>             for (;;) {
>                 process(opt);   // search for opt in options/flags
>                 opt = va_arg(ap, void*);
>                 if (!opt)       // NULL terminator
>                     break;
>             }
>             va_end(ap);
>         }
>
> --
> Glynn Clements <glynn at gclements.plus.com>
>
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