"Joel de Guzman" <joel@boost-consulting.com> wrote in message news:edu4v2$beb$1@sea.gmane.org...
Andy Little wrote:
BTW. By using a tuple rather than an array, then you can use representing zero and one. IOW zero<T> one<T> .
hence:
template <typename TL, typename TR> zero<typeof(TL() * TR() )> operator *( Tl , zero<TR>) { return zero<typeof(TL() * TR() )>(); } It should be relatively simple for the compiler to optimise such calcs away. Very useful for matrix calcs. (originally suggested by Geoffrey Irving).
Indeed. Also, with Fusion, you have the option to use purely constant sequences such as mpl::vector_c together with plain sequences, or even user defined sequences and adapted/converted structs/classes.
Right. I started looking into this scheme for math ops. I opted for a zero and a one, but then I figured that one + one should go to two etc. In the end I opted for a static_value<StaticValue,RunTimeType> StaticValue could then be any of mpl::int_ etc, though for mpl int_ division is ( can be) lossy so at that point the division should turn the result into the RunTimeType. other possibilities for StaticValue are a compile time rational, maybe with a long long value_type. At any point where the compile time value will run out of steam then the type will be automatically converted to the RunTimeType. All in all... how to take a simple idea and make it very very complicated :-) regards Andy Little