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[MPL] transform and unpack_args
by David Greene 28 Dec '04

28 Dec '04

All right, I'm still trying to figure out the MPL lambda stuff. I had expected this to work: template<typename Arg> some func { typedef ... type; }; typedef transform< sequence, some_func<_> >::type result; But I get a compiler error about a missing apply<> in some_func. This works: typedef transform< sequence, quote1<some_func> >::type result; I don't understand why the placeholder doesn't convert some_func to an appropriate metafunction class. Similarly, I tried to use unpack args: template<typename Arg1, typename Arg2> some_func2 { typedef ... type; }; typedef transform< zipped_sequence, unpack_args<some_func2<_,_> >::type result; The compiler complained about a missing apply<> in some_func2. Again, this worked: typedef transform< zipped_sequence, unpack_args<quote2<some_func2> > >::type result; Is it because I'm using _ rather than _1 and _2? The examples in the MPL manual using is_same, etc. work fine for me. Learning lots. Hope to learn more. :) -Dave

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read_write_mutex asserting
by jkharris7＠comcast.net 27 Dec '04

27 Dec '04

Boost 1.32.0 on MSVC71 I have a test where I have one writer and five readers, each attempting the appropriate lock for their function on a read_write_mutex, and none doing it recursively. It keeps asserting on me like this: .....Assertion failed: ++loop_count == 1, file read_write_mutex.cpp, line 173 The above happens (in do_write_lock()) when I select reader_priority. Something similar happens in do_read_lock() when I select writer_priority. while (m_state == -1 || m_num_readers_to_wake == 0) { BOOST_ASSERT(++loop_count == 1); //Check for invalid loop conditions (but will also detect spurious wakeups) ++m_num_waiting_readers; m_waiting_readers.wait(l); --m_num_waiting_readers; } In release mode, it's fine, but what could be causing these "spurious wakeups"?

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Newbie Issues linking Boost Unit Test Framework
by Malloc 27 Dec '04

27 Dec '04

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 hey there... I recently downloaded, built, and installed Boost 1.32. I am attempting to use the Boost Unit Test Framework but am running into difficulties figuring out which lib to link to. I am compiling with MS VC++ 7.1. The headers appear to be discovered as they should be, but the linker is failing to find the correct lib. I have tried many of the libs which were created by the build, but these all create more errors (typically to do with redefinitions of std:: functions). At this point I am only trying to compile the example code supplied on the projects web site. some of the libs I tried: libboost_prg_exec_monitor-vc71-mt-1_32.lib libboost_test_exec_monitor-vc71-mt-1_32.lib libboost_unit_test_framework-vc71-mt-1_32.lib some articles I found online advised turning on mutithreading in the compiler properities, enabling run time type identification, and setting exceptions to /EHa I've done all of this but nothing is working, it really just looks like a linker problem. Thanks for any help Dave - ------------------------- linking errors: Linking... main.obj : error LNK2019: unresolved external symbol "bool __cdecl boost::test_tools::tt_detail::test_and_continue_impl(bool,class boost::basic_wrap_stringstream<char> &,class boost::unit_test::basic_cstring<char const >,unsigned int,bool,enum boost::unit_test::log_level)" (?test_and_continue_impl@tt_detail@test_tools@boost@@YA_N_NAAV?$basic_ wrap_stringstream@D@3@V?$basic_cstring@$$CBD@unit_test@3@I0W4log_level @63@@Z) referenced in function "void __cdecl free_test_function(void)" (?free_test_function@@YAXXZ) main.obj : error LNK2019: unresolved external symbol "public: void __thiscall boost::unit_test::test_suite::add(class boost::unit_test::test_case *,unsigned long,int)" (?add@test_suite@unit_test@boost@@QAEXPAVtest_case@23@KH@Z) referenced in function "class boost::unit_test::test_suite * __cdecl init_unit_test_suite(int,char * * const)" (?init_unit_test_suite@@YAPAVtest_suite@unit_test@boost@@HQAPAD@Z) main.obj : error LNK2019: unresolved external symbol "public: __thiscall boost::unit_test::test_suite::test_suite(class boost::unit_test::basic_cstring<char const >)" (??0test_suite@unit_test@boost@@QAE@V?$basic_cstring@$$CBD@12@@Z) referenced in function "class boost::unit_test::test_suite * __cdecl init_unit_test_suite(int,char * * const)" (?init_unit_test_suite@@YAPAVtest_suite@unit_test@boost@@HQAPAD@Z) main.obj : error LNK2019: unresolved external symbol "class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const & __cdecl boost::unit_test::ut_detail::normalize_test_case_name(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &)" (?normalize_test_case_name@ut_detail@unit_test@boost@@YAABV?$basic_str ing@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@AAV45@@Z) referenced in function "class boost::unit_test::test_case * __cdecl boost::unit_test::create_test_case(void (__cdecl*)(void),class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?create_test_case@unit_test@boost@@YAPAVtest_case@12@P6AXXZV?$basic_s tring@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) main.obj : error LNK2001: unresolved external symbol "public: virtual unsigned long __thiscall boost::unit_test::test_case::size(void)const " (?size@test_case@unit_test@boost@@UBEKXZ) main.obj : error LNK2019: unresolved external symbol "protected: __thiscall boost::unit_test::test_case::test_case(class boost::unit_test::basic_cstring<char const >,bool,unsigned long,bool)" (??0test_case@unit_test@boost@@IAE@V?$basic_cstring@$$CBD@12@_NK1@Z) referenced in function "public: __thiscall boost::unit_test::function_test_case::function_test_case(void (__cdecl*)(void),class boost::unit_test::basic_cstring<char const >)" (??0function_test_case@unit_test@boost@@QAE@P6AXXZV?$basic_cstring@$$C BD@12@@Z) libcpmtd.lib(xdebug.obj) : error LNK2019: unresolved external symbol __malloc_dbg referenced in function "void * __cdecl operator new(unsigned int,struct std::_DebugHeapTag_t const &,char *,int)" (??2@YAPAXIABU_DebugHeapTag_t@std@@PADH@Z) libcpmtd.lib(_tolower.obj) : error LNK2001: unresolved external symbol __malloc_dbg libcpmtd.lib(xdebug.obj) : error LNK2019: unresolved external symbol __free_dbg referenced in function "void __cdecl operator delete(void *,struct std::_DebugHeapTag_t const &,char *,int)" (??3@YAXPAXABU_DebugHeapTag_t@std@@PADH@Z) LIBCMT.lib(crt0.obj) : error LNK2019: unresolved external symbol _main referenced in function _mainCRTStartup Debug/unittests.exe : fatal error LNK1120: 9 unresolved externals Build Time 0:00 Build log was saved at "file://e:\C++Source\unittests\Debug\BuildLog.htm" unittests - 11 error(s), 0 warning(s) - ---------------------- Done ---------------------- Build: 0 succeeded, 1 failed, 0 skipped - ---------------------------------------------------------------------- - ---------- -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.3 for non-commercial use <http://www.pgp.com> iQA/AwUBQc8OX06myMoV5dC/EQL6eACeI7zolVzltRg/K4qyEtKtezJCVnkAmgK6 xSo1f992Mg3vXkIyQ/2Nk1z+ =6lrH -----END PGP SIGNATURE-----

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Problems with lexical_cast
by Georgios Diamantopoulos 27 Dec '04

27 Dec '04

Hello, I am trying to convert from wchar_t to std::string with #include <iostream> #include <sstream> #include <boost/lexical_cast.hpp> int main() { std::cout << boost::lexical_cast<std::string>(L"blah") << std::endl; return 0; } but I get the following error: d:\SDK\boost\include\boost-1_32\boost\lexical_cast.hpp(158) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'std::basic_stringstream<_Elem,_Traits,_Alloc>::_Mystr' (or there is no acceptable conversion) Any ideas? This is with boost 1.3.2 and VC7.1 Best regards, Georgios

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units library
by Chris Goller 26 Dec '04

26 Dec '04

I've been looking around for a unit conversion library. I've seen some on http://groups.yahoo.com/group/boost/files/ but am wondering if any have been put into boost release yet. Thanks, Chris

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function_traits<> help, ASAP please!
by Hossein Haeri 26 Dec '04

26 Dec '04

Dear all, According to the Boost.Type_Traits I guess that function_traits<> is supposed to be of the most docile ones. After all it's got a few lines of comment... Don't know how, and why, but the following plain-jane programme #include <iostream> #include "boost\type_traits\function_traits.hpp" int main() { typedef void (*FType) (); typedef typename boost::function_traits<FType> ::result_type return_type; cin.get(); return 0; } Gives me the following error under GCC 3.3.1 (which I'm sure supports partial template specialisation): Compiler: Default compiler Building Makefile: "C:\Documents and Settings\Hossein\My Documents\My Programmes\Probability I\Distributions\7.2.1\Makefile.win" Executing make... make.exe -f "C:\Documents and Settings\Hossein\My Documents\My Programmes\Probability I\Distributions\7.2.1\Makefile.win" all g++.exe -D__DEBUG__ -c 7_2_1Main.cpp -o 7_2_1Main.o -I"C:/Dev-Cpp/include/c++/3.3.1" -I"C:/Dev-Cpp/include/c++/3.3.1/mingw32" -I"C:/Dev-Cpp/include/c++/3.3.1/backward" -I"C:/Dev-Cpp/lib/gcc-lib/mingw32/3.3.1/include" -I"C:/Dev-Cpp/include" -pg -g3 7_2_1Main.cpp: In instantiation of `boost::function_traits<void (*)()>': 7_2_1Main.cpp:57: instantiated from here 7_2_1Main.cpp:57: error: base class `boost::detail::function_traits_helper<void (**)()>' has incomplete type 7_2_1Main.cpp: In function `int main()': 7_2_1Main.cpp:57: error: no type named `result_type' in `struct boost::function_traits<void (*)()>' 7_2_1Main.cpp:57: error: using `typename' outside of template 7_2_1Main.cpp:57: error: ISO C++ forbids declaration of `return_type' with no type make.exe: *** [7_2_1Main.o] Error 1 Execution terminated Is he right? Is there anything particular I should had done, and I've not? TIA, --Hossein __________________________________ Do you Yahoo!? Read only the mail you want - Yahoo! Mail SpamGuard. http://promotions.yahoo.com/new_mail

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Random, Random Seed
by Hossein Haeri 25 Dec '04

25 Dec '04

Dear all, Using the following (slightly manipulated) sample code of Boost.Random, I'm always gettig the same sequence: boost::mt19937 rng; boost::uniform_int<> six(1,6); boost::variate_generator<boost::mt19937, boost::uniform_int<> > die(rng, six); for(size_t i = 0; i < 10; ++i) cout << die() << " "; I know that this is the consequence of the fact that the generators are deterministic ones, plus another fact that they start using the same seed. This behaviour, however, is not that much desirable, and I'm seaking some sort of good random seed. Any suggestions? TIA and Merry Christmas, --Hossein __________________________________ Do you Yahoo!? Yahoo! Mail - You care about security. So do we. http://promotions.yahoo.com/new_mail

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Looking for lazy if_
by Agoston Bejo 24 Dec '04

24 Dec '04

Hi! I'm looking for some "lazy" version of boost::mpl::if_. I'm not very much into MPL, so I don't really know either if such a function exists in boost or whether it can be easily constructed. Platform: VC++7.1 Thx in advance, Agoston This example shows you how it may cause problems that both "branches" of if_ get evaluated: //------------------------------------------------------------ #include <iostream> #include <vector> #include <boost/mpl/if.hpp> #include <boost/type_traits.hpp> using namespace std; using namespace boost; using namespace mpl; template<typename T> struct t_type { typedef typename if_< is_arithmetic<T>, T, typename T::value_type>::type // ERROR! type; }; int _tmain(int argc, _TCHAR* argv[]) { cout << typeid(t_type<int>::type).name() << endl; // 'int' cout << typeid(t_type<vector<double> >::type).name() << endl; // 'double' return 0; } //------------------------------------------------------------ Error message: error C2825: 'T::value_type': cannot form a qualified name see reference to class template instantiation 't_type<T>' being compiled with [ T=int ]

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Presentation and problem with uBlas.
by Le Farfadet Spatial 24 Dec '04

24 Dec '04

Hello every body out there ! Let me introduce myself : I am Yoann LE BARS and I am a fresh Boost user. I am french too, so please excuse my bad english. I have got a problem with Boost uBlas, I hope it is the good list to post about it. I have made a little exemple which show what is my problem (it compiles but I found the behaviour very strange) : http://cpp.sourceforge.net/pastebin.php?show=2439 Here is a version which works but do not satisfy me : http://cpp.sourceforge.net/pastebin.php?show=2440 Why does it not satisfy me ? Well, because I am fulling a sparse matrix with an identity matrix, the A matrix and the transposed A matrix : it is very redondant and A can be a very big matrix. That is the reason why I have make the LeastSquareMatrix class. I believe I have done something wrong in it, but what ? Best regards. Yoann LE BARS, alias Le Farfadet Spatial

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[MPL] replace_if question
by David Greene 23 Dec '04

23 Dec '04

Well, my mpl adventure continues. I'm trying to place pair members of a sequence with their keys: #include <boost/type_traits.hpp> #include <boost/mpl/pair.hpp> #include <boost/mpl/key_type.hpp> #include <boost/mpl/map.hpp> #include <boost/mpl/vector.hpp> #include <boost/mpl/replace_if.hpp> #include <boost/mpl/int.hpp> #include <iostream> #include <typeinfo> using namespace boost; using namespace boost::mpl; struct pair_base {}; template<typename Key, typename Value> struct pair_type : public pair<Key, Value>, private pair_base {}; template<typename Sequence> struct replaceit { typedef typename replace_if< Sequence, is_base_and_derived<pair_base, _>, key_type<map<>, _> >::type type; }; int main(void) { replaceit< vector< charm pair_type<int, int_<32> >, pair_type<long, int_<64> > double > >::type toprint; std::cout << typeid(toprint).name() << std::endl; return(0); }; I know this is incorrect because the pairs will be replaced by the key_type metafunction itself. If I add ::type to the end of key_type<map<>, _> the compiler complains that no ::first member exists: boost-1_32/boost/mpl/pair.hpp: In instantiation of `boost::mpl::first<mpl_::_>': replace.cc:25: instantiated from `boost::mpl::key_type_impl<boost::mpl::aux::map_tag>::apply<boost::mpl::map<mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, mpl_::_>' replace.cc:25: instantiated from `boost::mpl::key_type<boost::mpl::map<mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, mpl_::_>' replace.cc:25: instantiated from here boost-1_32/boost/mpl/pair.hpp:43: no type named `first' in `struct mpl_::_' What's the right way to do this? Furthermore, is there a better way to identify pairs in replace_if than deriving from a special class? All I can think of is writing a predicate class and specializing it for mpl::pair<U, V>. Seems like there should be an easier way. Thanks! -Dave

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