Re: [boost] [local] Any "active Boost library author" in favor of Boost.Local?

25 Nov 2011

      On Fri, Nov 25, 2011 at 2:42 PM, Thomas Heller
<thom.heller@googlemail.com> wrote:
...
Observe:
First of all, thanks, these examples are helping me a _lot_ :) Look
you can also turn the local function into the Phoenix function:

#include <boost/local/function.hpp>
#include <boost/phoenix/core.hpp>
#include <boost/phoenix/function.hpp>
#include <iostream>

struct x {
    void f() {
        void BOOST_LOCAL_FUNCTION_PARAMS(bind this) {
            this_->publ();
            this_->prot();
            this_->priv();
        } BOOST_LOCAL_FUNCTION_NAME(loc)
        // call it regularly:
        loc();
        // turn it into a phoenix function:
        boost::phoenix::function<decltype(loc)> phoenixf = loc;
        phoenixf()();
   }

public:
   void publ() { std::cout << "public" << std::endl; }
protected:
   void prot() { std::cout << "protected" << std::endl; }
private:
   void priv() { std::cout << "private" << std::endl; }
};

int main ( ) {
   x xx;
   xx.f();
   return 0;
}

In fact you could even trivially write a macro to directly generate
the Phoenix functor from the local scope:

struct x {
    void f() {
        void BOOST_LOCAL_FUNCTION_PARAMS(bind this) {
            this_->publ();
            this_->prot();
            this_->priv();
        } BOOST_LOCAL_FUNCTION_PHOENIX(phoenixloc)
        phoenixf()();
   }

public:
   void publ() { std::cout << "public" << std::endl; }
protected:
   void prot() { std::cout << "protected" << std::endl; }
private:
   void priv() { std::cout << "private" << std::endl; }
};

Where:

#define BOOST_LOCAL_FUNCTION_PHOENIX(name) \
    BOOST_LOCAL_FUNCTION_NAME(BOOST_PP_CAT(boost_local_phoenix, __LINE__)) \
    boost::phoenix::function<decltype(BOOST_PP_CAT(boost_local_phoenix,
__LINE__))> phoenixf = BOOST_PP_CAT(boost_local_phoenix, __LINE__);

Finally, I can trivially provide a BOOST_LOCAL_FUNCTION_TYPEOF(name)
to replace the decltype above (so it doesn't have to use C++11 at
all).

Would this be useful? Is this what you meant when you proposed to try
to use local functions to define Phoenix functions?
...
#include <boost/phoenix/core.hpp>
#include <boost/phoenix/function.hpp>
#include <iostream>
struct x {
   void f() {
       // call it regularly:
       f_impl()(this);
       // turn it into a phoenix function:
       boost::phoenix::function<f_impl> localf = f_impl();
       localf(this)();
   }
public:
   void publ() { std::cout << "public" << std::endl; }
protected:
   void prot() { std::cout << "protected" << std::endl; }
private:
   void priv() { std::cout << "private" << std::endl; }
   struct f_impl
   {
       typedef void result_type;
       template<typename This>
       void operator()(This this_) const
       {
           this_->publ();
           this_->prot(); // error
           this_->priv(); // error
       }
   };
};
int main ( ) {
   x xx;
   xx.f();
   return 0;
}
Thanks the clarifications.
--Lorenzo

Re: [boost] [local] Any "active Boost library author" in favor of Boost.Local?

Lorenzo Caminiti