Re: [boost] [local] Help for the Alternatives section

27 Mar 2011

      On Sat, Mar 26, 2011 at 6:19 PM, Lorenzo Caminiti <lorcaminiti@gmail.com> wrote:
...
How can I program the following code (its local function and `factor`
constant binding) using Boost.Phoenix, Boost.Lambda, and C++0x lambda
***Thanks for the examples but is there a way to make `factor` const
in the closure?***

Local functions can do that by `const bind factor` (const value) or
`const bind& factor` (const reference). How about Boost.Lambda,
Boost.Phoenix, and C++0x lambda?

For example, why C++0x doesn't allow the use of const in the closure?
Was this proposed to the standard committee?

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    double sum = 0.0;
    int factor = 10;

    std::vector<double> v(3);
    v[0] = 1.0; v[1] = 2.0; v[2] = 3.0;

    // NOTE `const&` for factor (but not supported by C++0x).
    std::for_each(v.begin(), v.end(), [&sum, const &factor](double num) {
        sum += factor * num;
        std::cout << "Summed: " << sum << std::endl;
    });

    std::cout << sum << std::endl;
    return 0;
}
...
functions? If you know, can you please reply with the actual code?
#include <boost/local/function.hpp>
#include <iostream>
#include <vector>
#include <algorithm>
int main() {
   double sum = 0.0;
   int factor = 10;
   void BOOST_LOCAL_FUNCTION_PARAMS(double num,
           // Variable `factor` bound as constant.
           bind& sum, const bind& factor) {
       sum += factor * num;
       std::cout << "Summed: " << sum << std::endl;
   } BOOST_LOCAL_FUNCTION_NAME(add)
   std::vector<double> v(3);
   v[0] = 1.0; v[1] = 2.0; v[2] = 3.0;
   // Local function `add` passed as template parameter.
   std::for_each(v.begin(), v.end(), add);
   return 0;
}
Thanks.

--
Lorenzo