[Boost-users] Template instantiation, function arguments and Boost.Preprocessor

From: Hicham Mouline (hicham_at_[hidden])
Date: 2008-01-28 10:20:00

hi,

i have a template function, the arguments of which i wish to have depend on a non-type int template argument:

template<int n>
double f<n>( double arg0, double arg1, ..., double argn )   // ... is not the variadic notation for var number of args
{
 // for(int i=0; i<n; i++)
 // code
 return sum;
}

int main()
{
 return x = f<3>( 1.0, 2.0, 3.0 );
}

BOOST_PP_REPEAT can't seem to do the job as the template argument n needs to be known
at the preprocessing stage, which happens before the template instantiation stage (
this is part of compilation)

PS: I did some perf tests comparing
   inline f(double a0, double a1, double a2)
calls in an intensive loop, vs 
   inline f(double a[3])  // degenrates to pointer
with intel compiler and max optim, and the top version is faster...

regards,