On Sun, May 8, 2011 at 1:06 PM, Lorenzo Caminiti <lorcaminiti@gmail.com> wrote:
On Sun, May 8, 2011 at 11:22 AM, Mathias Gaunard
The type erasure appear unnecessary, and this implementation has big forwarding problems.
What about
Yes, makes sense. Using your suggestion:
Hi all, the following code compiles and runs just fine on GCC but it given the error below on MSVC. The error seems to be about a conversion to boost::function_base inside Boost.Function... #include <boost/local/function.hpp> #include <boost/function.hpp> #include <vector> #include <algorithm> #include <iostream> #include <string> namespace boost { namespace local { namespace function { template<typename F0, typename F1, typename F2 = void, typename F3 = void> struct overload {}; // Specialization for 2 functions. template<typename F0, typename F1> struct overload<F0, F1>: F0, F1 { overload(F0 const& f0, F1 const& f1): F0(f0), F1(f1) {} using F0::operator(); using F1::operator(); }; }}} // namespace boost::local::function // More specializations to overload also with F2, F3, etc. int main() { char sep = '\n'; void BOOST_LOCAL_FUNCTION_PARAMS(const double& item, const bind& sep) { std::cout << item << sep; } BOOST_LOCAL_FUNCTION_NAME(print_double) void BOOST_LOCAL_FUNCTION_PARAMS(const std::string& item, const bind& sep) { std::cout << item << sep; } BOOST_LOCAL_FUNCTION_NAME(print_string) boost::function< void (const double&) > pd(print_double); boost::function< void (const std::string&) > ps(print_string); boost::local::function::overload< boost::function< void (const double&) > , boost::function< void (const std::string&) > > print(pd, ps); std::vector<double> d(2); d[0] = 1.2; d[1] = 3.4; std::for_each(d.begin(), d.end(), print); std::vector<std::string> s(3); s[0] = "ab"; s[1] = "cd"; s[2] = "ef"; std::for_each(s.begin(), s.end(), ps); return 0; } E:\sandbox\boost-sandbox-local\libs\local\example>bjam -q overload_va ...patience... ...found 714 targets... ...updating 3 targets... compile-c-c++ bin\msvc-8.0\debug\threading-multi\overload_va.obj overload_va.cpp e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(601) : error C2594: 'argument' : ambiguous conversions from 'boost::local::function::overloa d<F0,F1> *' to 'const boost::function_base *' with [ F0=boost::function<void (const double &)>, F1=boost::function<void (const std::string &)> ] e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(492) : see reference to function template instantiation 'bool boost::detail::functio n::basic_vtable1<R,T0>::assign_to<F>(FunctionObj,boost::detail::function::functi on_buffer &,boost::detail::function::function_obj_tag)' being compiled with [ R=void, T0=const double &, F=boost::local::function::overload<boost::function<void (const doubl e &)>,boost::function<void (const std::string &)>>, FunctionObj=boost::local::function::overload<boost::function<void (c onst double &)>,boost::function<void (const std::string &)>> ] e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(909) : see reference to function template instantiation 'bool boost::detail::functio n::basic_vtable1<R,T0>::assign_to<Functor>(F,boost::detail::function::function_b uffer &)' being compiled with [ R=void, T0=const double &, Functor=boost::local::function::overload<boost::function<void (const double &)>,boost::function<void (const std::string &)>>, F=boost::local::function::overload<boost::function<void (const doubl e &)>,boost::function<void (const std::string &)>> ] e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(722) : see reference to function template instantiation 'void boost::function1<R,T0> ::assign_to<Functor>(Functor)' being compiled with [ R=void, T0=const double &, Functor=boost::local::function::overload<boost::function<void (const double &)>,boost::function<void (const std::string &)>> ] e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(1043 ) : see reference to function template instantiation 'boost::function1<R,T0>::fu nction1<Functor>(Functor,int)' being compiled with [ R=void, T0=const double &, Functor=boost::local::function::overload<boost::function<void (const double &)>,boost::function<void (const std::string &)>> ] overload_va.cpp(57) : see reference to function template instantiation ' boost::function<Signature>::function<boost::local::function::overload<F0,F1>>(Fu nctor,int)' being compiled with [ Signature=void (const double &), F0=boost::function<void (const double &)>, F1=boost::function<void (const std::string &)>, Functor=boost::local::function::overload<boost::function<void (const double &)>,boost::function<void (const std::string &)>> ] e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(601) : error C2594: 'argument' : ambiguous conversions from 'boost::local::function::overloa d<F0,F1> *' to 'const boost::function_base *' with [ F0=boost::function<void (const double &)>, F1=boost::function<void (const std::string &)> ] e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(492) : see reference to function template instantiation 'bool boost::detail::functio n::basic_vtable1<R,T0>::assign_to<F>(FunctionObj,boost::detail::function::functi on_buffer &,boost::detail::function::function_obj_tag)' being compiled with [ R=void, T0=const std::basic_string<char,std::char_traits<char>,std::allocato r<char>> &, F=boost::local::function::overload<boost::function<void (const doubl e &)>,boost::function<void (const std::string &)>>, FunctionObj=boost::local::function::overload<boost::function<void (c onst double &)>,boost::function<void (const std::string &)>> ] e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(909) : see reference to function template instantiation 'bool boost::detail::functio n::basic_vtable1<R,T0>::assign_to<Functor>(F,boost::detail::function::function_b uffer &)' being compiled with [ R=void, T0=const std::basic_string<char,std::char_traits<char>,std::allocato r<char>> &, Functor=boost::local::function::overload<boost::function<void (const double &)>,boost::function<void (const std::string &)>>, F=boost::local::function::overload<boost::function<void (const doubl e &)>,boost::function<void (const std::string &)>> ] e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(722) : see reference to function template instantiation 'void boost::function1<R,T0> ::assign_to<Functor>(Functor)' being compiled with [ R=void, T0=const std::basic_string<char,std::char_traits<char>,std::allocato r<char>> &, Functor=boost::local::function::overload<boost::function<void (const double &)>,boost::function<void (const std::string &)>> ] e:\sandbox\boost-trunk.windows\boost/function/function_template.hpp(1043 ) : see reference to function template instantiation 'boost::function1<R,T0>::fu nction1<Functor>(Functor,int)' being compiled with [ R=void, T0=const std::basic_string<char,std::char_traits<char>,std::allocato r<char>> &, Functor=boost::local::function::overload<boost::function<void (const double &)>,boost::function<void (const std::string &)>> ] overload_va.cpp(57) : see reference to function template instantiation ' boost::function<Signature>::function<boost::local::function::overload<F0,F1>>(Fu nctor,int)' being compiled with [ Signature=void (const std::string &), F0=boost::function<void (const double &)>, F1=boost::function<void (const std::string &)>, Functor=boost::local::function::overload<boost::function<void (const double &)>,boost::function<void (const std::string &)>> ] call "C:\Program Files\Microsoft Visual Studio 8\VC\vcvarsall.bat" x86 >nul cl /Zm800 -nologo @"bin\msvc-8.0\debug\threading-multi\overload_va.obj.rsp" ...failed compile-c-c++ bin\msvc-8.0\debug\threading-multi\overload_va.obj... ...failed updating 1 target... Thanks a lot! -- Lorenzo