Re: [Boost-users] [mpl::map & mpl::transform] Problems usingmpl::map in mpl::for_each

Dave, Here is a small example which produces errors: #include <iostream> #include <functional> #include #include #include #include #include #include #include #include #include #include using namespace std; using namespace boost; template<class T> struct wrap{}; struct dispatcher { template<class Seq> void dispatch() { int i=0; mpl::for_eachmpl::_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 >(); } 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' 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' 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 ] 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 ] 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 ] c:\program files (x86)\boost\boost_1_33_1\boost\mpl\eval_if.hpp(41) : see reference to class template instantiation 'boost::mpl::transform1' being compiled with [ P1=boost::mpl::map, P2=wrapboost::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' being compiled with [ C=boost::mpl::or_boost::mpl::na,boost::mpl::is_lambda_ex pressionboost::mpl::_1>,boost::mpl::not_boost::mpl::_1>>>, F1=boost::mpl::transform1,wrap,boost::mpl::na>, F2=boost::mpl::transform2,wrap,boost::mpl::na,boost::mpl::na> ] d:\projects\cpp_projects\cpptests\messagewrappertests\main2.cpp(26) : see reference to class template instantiation 'boost::mpl::transform' being compiled with [ Seq1=boost::mpl::map, Seq2OrOperation=wrapboost::mpl::_1 ] d:\projects\cpp_projects\cpptests\messagewrappertests\main2.cpp(81) : see reference to function template instantiation 'void dispatcher::dispatch>(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::result2_>::type ] and [ Sequence=boost::mpl::map ] 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 ] 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 ] 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" 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 >::type

...

(dispatcher_type());

mpl::for_each >(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 >::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