On Thu, Oct 14, 2010 at 11:41 PM, alfC <alfredo.correa@gmail.com> wrote:
On Oct 14, 10:30 pm, OvermindDL1 <overmind...@gmail.com> wrote:
On Thu, Oct 14, 2010 at 11:09 PM, alfC <alfredo.cor...@gmail.com> wrote:
Hi,
I am using Boost.Fusion lately. Sometimes one has a function with several parameters,
int f(double d , int i , std::string s){ ...bla bla ... }
the logic of the program says that sometimes that same funcion will be called by generic code and in such case it is better if "f" where defined as taking a fusion::vector as argument.
int f(fusion::vector<double, int, std::string>) // another function, could be an overload even
since there is only one why to define this adaptor function, e.g. int f(fusion::vector<double, int, std::string> x){ return f(at_c<0>(x), at_c<1>(x), at_c<2>(x));\ }
and it is pretty mechanical. I was wondering if it would be a good idea to have, with consistency with the BOOST_FUSION_ADAPT_STRUCT, something called BOOST_FUSION_ADAPT_FUNCTION
BOOST_FUSION_ADAPT_FUNCTION( int, f, double, int, std::string ) (or something like that) that defines the second / fusion-compatible version of f.
It could be even a
BOOST_FUSION_DEFINE_FUNCTION( int, f, (double, d), (int, i), (std::string, s), ( ... code using variables d, i, s or at_key<d_>, at_key<i_>, at_key<s_> ... ) )
that defines simultaneously the raw-C function, f(double, int, string) *and* the fusion friendly version f(vector<...>). I could probably program these macro for specific cases but not a general one since I don't know enough macro syntax to make it work.
Do you think it is a good idea or it is already doable with existing Fusion features?
It should already be doable, given example: // include fusion here
int f(double d , int i , std::string s){ ...bla bla ... }
int main(void) { boost::fusion::vector<double,int,std::string myVec(3.14, 42, "Hello World!"); return boost::fusion::invoke(&f, myVec); }
cool. one question: does it work for member functions as well?
It works for any thing that fulfills the Boost.Fusion callable concept as outlined here: http://www.boost.org/doc/libs/1_44_0/libs/fusion/doc/html/fusion/functional/... So yes, it works for member functions (where the class instance it is called from is the first entry in the fusion vector/list/whatever).