Dave, Here is a small example which produces errors: #include <iostream> #include <functional> #include <boost/ref.hpp> #include <boost/bind.hpp> #include <boost/array.hpp> #include <boost/utility.hpp> #include <boost/bind/placeholders.hpp> #include <boost/mpl/int.hpp> #include <boost/mpl/map.hpp> #include <boost/mpl/for_each.hpp> #include <boost/mpl/vector.hpp> #include <boost/mpl/transform.hpp> using namespace std; using namespace boost; template<class T> struct wrap{}; struct dispatcher { template<class Seq> void dispatch() { int i=0; mpl::for_each<typename mpl::transform<Seq, wrap<mpl::_1>
::type>(bind<void>(*this, i, _1)); cout << "I did: " << i << " iterations\n"; }
template<class T> void operator()(int& i, wrap<T>)const { cout <<"pos: " << i << ", type: " << typeid(T).name() << '\n'; ++i; } }; #include <string> int main(int argc, char* argv[]) { dispatcher d; d.dispatch<mpl::map<int, long, double> >(); } Sorry for so many headers, some of them are not required... Visual C++ 2005 blames: c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\preprocessed\plain\map10.hpp(88) : error C2825: 'P2': must be a class or namespace when followed by '::' c:\program files (x86)\boost\boost_1_33_1\boost\mpl\aux_\preprocessed\plain\map.hpp(68) : see reference to class template instantiation 'boost::mpl::map3<P0,P1,P2>' being compiled with [ P0=int, P1=long, P2=double ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\aux_\has_tag.hpp(20) : see reference to class template instantiation 'boost::mpl::map<T0,T1,T2>' being compiled with [ T0=int, T1=long, T2=double ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\sequence_tag.hpp(112) : see reference to class template instantiation 'boost::mpl::aux::has_tag<T>' being compiled with [ T=boost::mpl::map<int,long,double> ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\clear.hpp(29) : see reference to class template instantiation 'boost::mpl::sequence_tag<Sequence>' being compiled with [ Sequence=boost::mpl::map<int,long,double> ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\transform.hpp(113) : see reference to class template instantiation 'boost::mpl::clear<Sequence>' being compiled with [ Sequence=boost::mpl::map<int,long,double> ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\eval_if.hpp(41) : see reference to class template instantiation 'boost::mpl::transform1<P1,P2,P3>' being compiled with [ P1=boost::mpl::map<int,long,double>, P2=wrap<boost::mpl::_1>, P3=boost::mpl::na ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\transform.hpp(138) : see reference to class template instantiation 'boost::mpl::eval_if<C,F1,F2>' being compiled with [ C=boost::mpl::or_<boost::mpl::is_na<boost::mpl::na>,boost::mpl::is_lambda_ex pression<wrap<boost::mpl::_1>>,boost::mpl::not_<boost::mpl::is_sequence<wrap <boost::mpl::_1>>>>, F1=boost::mpl::transform1<boost::mpl::map<int,long,double>,wrap<boost::mpl:: _1>,boost::mpl::na>, F2=boost::mpl::transform2<boost::mpl::map<int,long,double>,wrap<boost::mpl:: _1>,boost::mpl::na,boost::mpl::na> ] d:\projects\cpp_projects\cpptests\messagewrappertests\main2.cpp(26) : see reference to class template instantiation 'boost::mpl::transform<Seq1,Seq2OrOperation>' being compiled with [ Seq1=boost::mpl::map<int,long,double>, Seq2OrOperation=wrap<boost::mpl::_1> ] d:\projects\cpp_projects\cpptests\messagewrappertests\main2.cpp(81) : see reference to function template instantiation 'void dispatcher::dispatch<boost::mpl::map<T0,T1,T2>>(void)' being compiled with [ T0=int, T1=long, T2=double ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\preprocessed\plain\map10.hpp(88) : error C2039: 'first' : is not a member of '`global namespace'' c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\preprocessed\plain\map10.hpp(89) : error C2146: syntax error : missing ',' before identifier 'first' c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\preprocessed\plain\map10.hpp(89) : error C2825: 'P2': must be a class or namespace when followed by '::' c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\preprocessed\plain\map10.hpp(89) : error C2039: 'second' : is not a member of '`global namespace'' c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\preprocessed\plain\map10.hpp(90) : error C2146: syntax error : missing ',' before identifier 'second' c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\preprocessed\plain\map10.hpp(91) : error C2977: 'boost::mpl::m_item' : too many template arguments c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\item.hpp(79) : see declaration of 'boost::mpl::m_item' c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\preprocessed\plain\map10.hpp(92) : error C2955: 'boost::mpl::m_item' : use of class template requires template argument list c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\item.hpp(79) : see declaration of 'boost::mpl::m_item' c:\program files (x86)\boost\boost_1_33_1\boost\mpl\map\aux_\preprocessed\plain\map10.hpp(92) : error C2504: 'boost::mpl::m_item' : base class undefined c:\program files (x86)\boost\boost_1_33_1\boost\mpl\clear.hpp(31) : error C2504: 'boost::mpl::clear_impl<Tag>::apply<Sequence>' : base class undefined with [ Tag=boost::mpl::aux::sequence_tag_impl<false,false>::result2_<boost::mpl::ma p<int,long,double>>::type ] and [ Sequence=boost::mpl::map<int,long,double> ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\transform.hpp(113) : error C2039: 'type' : is not a member of 'boost::mpl::clear<Sequence>' with [ Sequence=boost::mpl::map<int,long,double> ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\transform.hpp(113) : error C3203: 'type' : unspecialized class template can't be used as a template argument for template parameter 'Sequence', expected a real type c:\program files (x86)\boost\boost_1_33_1\boost\mpl\transform.hpp(113) : error C2039: 'type' : is not a member of 'boost::mpl::clear<Sequence>' with [ Sequence=boost::mpl::map<int,long,double> ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\transform.hpp(113) : error C3203: 'type' : unspecialized class template can't be used as a template argument for template parameter 'Sequence', expected a real type Many thanks, Ovanes P.S. I am trying to make a map with 150 elements. I posted on this issue 2 posts, can you please take a look? http://lists.boost.org/boost-users/2006/10/23057.php -----Original Message----- From: David Abrahams [mailto:dave@boost-consulting.com] Sent: Thursday, November 02, 2006 10:05 PM To: boost-users@lists.boost.org Subject: Re: [Boost-users] [mpl::map & mpl::transform] Problems usingmpl::map in mpl::for_each "Ovanes Markarian" <om_boost@keywallet.com> writes:
Hello,
I have some slightly different code, which is presented in C++ Template Metaprogramming book to use the mpl::for_each function:
mpl::for_each< mpl::transform<seq, wrap<_1> >::type
(dispatcher_type());
mpl::for_each<seq, wrap<_> >(dispatcher_type()); would be simpler
The deviation from the book is that my seq it not mpl::vector<...>, but mpl::map<...>
In the docs is written, that mpl::transform operates on Forward Sequence. In the doc of forward sequence is stated that mpl::map is a model of it.
The last release of mpl::map had some considerable bugs. Have you tried the latest version from the CVS HEAD (or RC_1_34_0)?
Unfortunately this code does not compile. I could transform the map to vector, but I would not like doing it, since that would cost compile time and slow down the compilation. Is it a known issue or should not I expect map to work with transform?
The code could "not compile" for many other reasons than that "map doesn't work with transform." Have you tried to compile typedef mpl::transform<seq, wrap<_1> >::type x;
I also tried using itertors on seq, but that did not help.
I think we'll need a lot more detail to be able to help you. -- Dave Abrahams Boost Consulting www.boost-consulting.com _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users