From: Markus Werle (numerical.simulation_at_[hidden])
Date: 2008-03-10 12:38:07
Steven Watanabe <watanabesj <at> gmail.com> writes:
>
> AMDG
>
> Markus Werle wrote:
> > Sorry if I do not get that one.
> >
>
> The definition of expr is something like:
>
> template<class Tag, class Args, int Arity = Args::arity>
> struct expr;
>
> template<class Tag, class Args>
> struct expr<Tag, Args, 0> {
> typename Args::arg0 arg0;
> };
> template<class Tag, class Args>
> struct expr<Tag, Args, 1> {
> typename Args::arg0 arg0;
> };
> template<class Tag, class Args>
> struct expr<Tag, Args, 2> {
> typename Args::arg0 arg0;
> typename Args::arg1 arg1;
> };
>
OK, and what is the advantage of the 3rd template argument Arity then?
AFAICS this is needed for the BOOST_PP_ITERATION magic, but strictly speaking
it is not necessary for the data _representation_, right?
Also I feel very uncomfortable about those typedefs above ...
can't we get along accessing by index when in need for it?
Markus