July 2010 - Boost-users - lists.boost.org

Memory management of boost::mutex
by Markus Henschel 13 Jul '10

13 Jul '10

Hi, we have a custom memory manager that overrides global new/delete. It is currently not thread safe. Because we require thread safety now I wanted to ad a mutex and some locks around the critical parts. Unfortunately boost::mutex allocates memory itself. So while the memory manager is created it tries to create it's mutex which causes global new to be called which calls the memory manager which is not created yet. I solved this for several data structures inside the memory manager by using custom allocators and by overriding the memory managers new operator to directly call malloc and free for its needs. But I don't see a way to customize memory management in boost mutex. Can it be achieved somehow? Thanks Markus Henschel Lead Programmer YAGER Development GmbH Pfuelstraße 5 10997 Berlin Germany www.yager.de Sitz der Gesellschaft: Berlin | Geschäftsführer: Timo Ullmann, Uwe Beneke Amtsgericht Berlin-Charlottenburg | HRB 78261 | USt-ID-Nr. DE 212404124

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Boost 1.42.0: DateTime ISO Timestamp Parsing Fix
by Peter Klotz 13 Jul '10

13 Jul '10

Boost.DateTime 1.42.0 falsely converts "20100713" into "20100713T201007.300000" using from_iso_string(). Example Code: const boost::posix_time::ptime time=boost::posix_time::from_iso_string("20100713"); std::cout << boost::posix_time::to_iso_string(time) << std::endl; Current Result: 20100713T201007.300000 The error is caused by boost::date_time::split(). The attached patch corrects split() so that an exception is thrown later in parse_delimited_time_duration(). We assume this behaviour to be better than creating a ptime that contains wrong values. Regards, Peter.

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ptr_vector documentation
by Paul Harris 12 Jul '10

12 Jul '10

Hi, Why is it that ptr_vector's documentation has everything EXCEPT the header that I need to include? http://www.boost.org/doc/libs/1_43_0/libs/ptr_container/doc/ptr_vector.html no mention of what headers are required... very frustrating, so either I have to look through all the other documentation and hope I find it, or look for the file on the harddisk, or trial-by-error... this problem seems to be common in boost documentation, is there a good reason why, or is this something that can be improved? thanks Paul

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[ProgramOptions] Hex argument values
by Robert Jones 12 Jul '10

12 Jul '10

Hi All Bit of a newbie to Boost.ProgramOptions... Is there a 'proper' way to specify that an argument has a hex value? I could take it as string and then check, but I'd prefer to let ProgramOptions do it for me. Thanks, Rob.

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[Memory] Problems when calling virtual class function
by Janez Urevc 12 Jul '10

12 Jul '10

Hello, I am doing a research about Monte Carlo Tree Search efficiency on KBNK chess ending. I use framework and algorithm implementation in C++. Since I had some memory leaks, that I couldn't manage to identify, I decided to try Boost's shared_ptr. I reorganized the whole thing to use it, but I encountered a problem, which I cannot solve. The problem occurs, when I try to call class member function, which was declared "virtual" in super class. If I try to call functions, that are not redefined, everything works as expected. Ex.: class Base{ public: int val = 0; virtual void fun(){ /* do something */} }; class Derived : public Base{ public: void fun(){ /*redefined*/} void fun1(){ /*not redefined*/} }; /* ... */ boost::shared_ptr<Base> object(new Derived); object->val = 1; //this works ok object->fun1(); //also works ok object->fun(); //does not work, I get segfault and "<symbol is not available>" error in stack trace I get the same problem if I use boost::shared_ptr<Derived> instead of boost::shared_ptr<Base>. If I change fun() in Base class to non-virtual thing works (then I cannot use polymorphism of course). I use Boost 1.4 on Ubuntu 10.04. Hope someone could help me. JAnez --- Janez Urevc Pod anteno 3a 6320 Portorož Slovenija GSM: +386 (0)40 731 632 email: janez(a)janezek.org blog: http://www.janezek.org skype: slashrsm gtalk: janez(a)janezek.org twitter: slashrsm

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Is there any Template [Meta] Programming Technique available to achieve this?
by A L 12 Jul '10

12 Jul '10

Hi, I am working on a UI system. I have created a prototype factory using the regular pattern. The abstract "product" class (each product class takes only the "name" of the product as the parameter) which is the parent of all the product classes that the proto-factory creates, contains a lonnnnnng enumeration - each product class uses some of the enumerators contained inside the enumeration. Having developed the factory, I have realized that there are various other "thing" that I can "manufacture" using the same approach. So, I want to re-use the proto-factory. For that I need to templatize the product classes and the factory class and need to "manufacture" the proto-factory itself from a proto-factory generator class (another factory, that is). The problem is, the different enumerators/constants required by each product class don't allow me genericize the design. For example, I have an Align class which uses the following enumeration: enum text_align_type { text_align_not_set = -1, text_align_left = align_left_key, text_align_center = align_center_key, text_align_right = align_right_key, text_align_justified = align_just_key }; Now the Align class takes the string "Align" as its constructor parameter and sets one of its values to text_align_not_set using the initialization list. It makes use of all of the above enumeration constants in its validation and so on. Since the proto-factory is creating the products by cloning using the copy constructors of the registered objects, I think a solution would be to pass all these enumeration constants in the constructor of each product class (besides the productName argument which is already being passed to each product class constructor). This way, I will need to create/registered these products only once in the proto-factory registry and subsequent products will then be generated/manufactured (i.e. copy-constructed) from the registered products. PROBLEM ======== Passing enumeration constants in constructors for the sole purpose of validation, etc. seems to be a bit inefficient to me. Yet I also want to re-use the design. I wonder if I could use Boost and its template/meta-programming magic to somehow pass these enumeration constants to each product class without having to pass them in product class constructors. Any ideas? -Asif

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How to replace the std::string to myown string in boost::filesystem
by SONGFY 12 Jul '10

12 Jul '10

For the changing of the std::string allocator, I retypedef the std::string to my string, just like this: namespace MyNamespace { template<typename Elem, typename Traits> class basic_string : public std::basic_string<Elem, Traits, STLAllocator<Elem> > { // reimplement the typedefs and constructors. }; typedef basic_string<char, std::char_traits<char> > string; typedef basic_string<wchar_t, std::char_traits<wchar_t> > wstring; } So I want the boost::filesystem use my own string type, but I met some problem: The code like this: namespace MyNamespace { struct path_traits; typedef boost::filesystem::basic_path<string, path_traits> path; typedef boost::filesystem::basic_path<wstring, path_traits> wpath; struct path_traits { typedef string internal_string_type; typedef string external_string_type; static external_string_type to_external( const path &, const internal_string_type & src ) { return src; } static internal_string_type to_internal( const external_string_type & src ) { return src; } }; typedef boost::filesystem::basic_recursive_directory_iterator<path> recursive_directory_iterator; typedef boost::filesystem::basic_recursive_directory_iterator<wpath> wrecursive_directory_iterator; } namespace boost { namespace filesystem { template<> struct is_basic_path<MyNamespace::path> { BOOST_STATIC_CONSTANT( bool, value = true ); }; template<> struct is_basic_path<MyNamespace::wpath> { BOOST_STATIC_CONSTANT( bool, value = true ); }; } } namespace MyNamespace { inline bool is_directory( const path & ph ) { return boost::filesystem::is_directory<path>( ph ); } inline bool is_directory( const wpath & ph ) { return boost::filesystem::is_directory<wpath>( ph ); } } For replace all the function is a huge work, and in this way I can not replace it for I met this function: BOOST_FILESYSTEM_DECL file_status status_api( const std::string & ph, system::error_code & ec ); Maybe this way is too bother, I think there must be an easy way to replace the string. Is there any way to resolve this? Thank you.

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[Users][Property Tree] Problem with compiling basic_tree<std::string, ...>
by Jani Plesnicar 11 Jul '10

11 Jul '10

Hy i have problem with #include "windows.h" #include <boost/bind.hpp> #include <boost/function.hpp> #include <iostream> #include <map> #include <boost/property_tree/ptree.hpp> #include <boost/property_tree/json_parser.hpp> #include <boost/property_tree/info_parser.hpp> #include <boost/property_tree/xml_parser.hpp> #include <boost/property_tree/exceptions.hpp> #include <boost/property_tree/ptree_fwd.hpp> #include <boost/property_tree/string_path.hpp> #include <boost/property_tree/stream_translator.hpp> #include <boost/property_tree/exceptions.hpp> #include <boost/property_tree/detail/ptree_utils.hpp> namespace property_tree = boost::property_tree; namespace json_parser = boost::property_tree::json_parser; namespace info_parser = boost::property_tree::info_parser; namespace xml_parser = boost::property_tree::xml_parser; class DataHold { public: const DataHold& DataHold::operator=(const DataHold& oth) { return oth; } DataHold::DataHold(void) : _dht(DHT_NULL) {/**/} DataHold::DataHold(int* d) : _d_pint(d), _dht(DHT_PINT) {/**/} DataHold::DataHold(char* d) : _d_pchar(d), _dht(DHT_PCHAR) {/**/} DataHold::DataHold(float* d) : _d_pfloat(d), _dht(DHT_PFLOAT) {/**/} DataHold::DataHold(double* d) : _d_pdouble(d), _dht(DHT_PDOUBLE) {/**/} DataHold::DataHold(bool* d) : _d_pbool(d), _dht(DHT_PBOOL) {/**/} DataHold::DataHold(std::string* d) : _d_pstdstr(d), _dht(DHT_PSTDSTRING) {/**/} typedef enum { DHT_NULL, DHT_PINT, DHT_PCHAR, DHT_PBOOL, DHT_PFLOAT, DHT_PDOUBLE, DHT_PSTDSTRING } DATA_HOLD_TYPE; DATA_HOLD_TYPE DataHold::TypeIndex() const {return _dht;} int* _d_pint; char* _d_pchar; bool* _d_pbool; float* _d_pfloat; double* _d_pdouble; std::string* _d_pstdstr; bool empty() const { return _dht==DHT_NULL; } friend std::ostream& operator<< (std::ostream &os,const DataHold &me) { os << (int)(me.TypeIndex()); return os; } private: friend class property_tree::basic_ptree<std::string,DataHold>; void swap(DataHold& x) { int* dint = x._d_pint; char* dchr = x._d_pchar; bool* dbol = x._d_pbool; float* dflt = x._d_pfloat; double* ddbl = x._d_pdouble; std::string* dstr = x._d_pstdstr; DATA_HOLD_TYPE dht = x._dht; x._d_pint = this->_d_pint; x._d_pchar = this->_d_pchar; x._d_pbool = this->_d_pbool; x._d_pfloat = this->_d_pfloat; x._d_pdouble = this->_d_pdouble; x._d_pstdstr = this->_d_pstdstr; x._dht = this->_dht; this->_d_pint = dint; this->_d_pchar = dchr; this->_d_pbool = dbol; this->_d_pfloat = dflt; this->_d_pdouble = ddbl; this->_d_pstdstr = dstr; this->_dht = dht; } DATA_HOLD_TYPE _dht; }; namespace prop_tree { typedef property_tree::basic_ptree<std::string,DataHold> ptreedh; }; int main(int argc, char** argv) { std::string nejm = "Test"; std::string priimk = "Bla"; int dejt[3] = {14, 06, 2010}; float height = 181.5f; float weight = 57.5f; prop_tree::ptreedh ptree_rt; prop_tree::ptreedh pt = ptree_rt.put("oseba.ime", DataHold(&nejm)); std::cout << ptree_rt.get_value("oseba.ime"); system("pause"); return 0; } I get these errors in Visual Studio C++ 2008 when trying to compile. 1>------ Build started: Project: DebugServerLib, Configuration: Debug Win32 ------ 1>Compiling... 1>main.cpp 1>p:\cpp\boost\include\boost-1_42\boost\property_tree\detail\ptree_implementation.hpp(655) : error C2027: use of undefined type 'boost::property_tree::translator_between<Internal,External>' 1> with 1> [ 1> Internal=DataHold, 1> External=std::basic_string<char,std::char_traits<char>,std::allocator<char>> 1> ] 1> p:\cpp\boost\include\boost-1_42\boost\property_tree\detail\ptree_implementation.hpp(666) : see reference to function template instantiation 'std::basic_string<_Elem,_Traits,_Ax> boost::property_tree::basic_ptree<Key,Data>::get_value<std::basic_string<_Elem,_Traits,_Ax>>(const Type &) const' being compiled 1> with 1> [ 1> _Elem=char, 1> _Traits=std::char_traits<char>, 1> _Ax=std::allocator<char>, 1> Key=std::string, 1> Data=DataHold, 1> Type=std::basic_string<char,std::char_traits<char>,std::allocator<char>> 1> ] 1> p:\cpp\debugserverlib\debugserverlib\main.cpp(156) : see reference to function template instantiation 'std::basic_string<_Elem,_Traits,_Ax> boost::property_tree::basic_ptree<Key,Data>::get_value<char>(const Ch *) const' being compiled 1> with 1> [ 1> _Elem=char, 1> _Traits=std::char_traits<char>, 1> _Ax=std::allocator<char>, 1> Key=std::string, 1> Data=DataHold, 1> Ch=char 1> ] 1>p:\cpp\boost\include\boost-1_42\boost\property_tree\detail\ptree_implementation.hpp(655) : error C2955: 'boost::type' : use of class template requires template argument list 1> p:\cpp\boost\include\boost-1_42\boost\type.hpp(14) : see declaration of 'boost::type' 1>p:\cpp\boost\include\boost-1_42\boost\property_tree\detail\ptree_implementation.hpp(655) : error C2780: 'boost::enable_if<boost::property_tree::detail::is_character<Ch>,std::basic_string<Ch>>::type boost::property_tree::basic_ptree<Key,Data>::get_value(const Ch *) const' : expects 1 arguments - 2 provided 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1> p:\cpp\boost\include\boost-1_42\boost\property_tree\ptree.hpp(344) : see declaration of 'boost::property_tree::basic_ptree<Key,Data>::get_value' 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1>p:\cpp\boost\include\boost-1_42\boost\property_tree\detail\ptree_implementation.hpp(655) : error C2780: 'boost::disable_if<boost::property_tree::detail::is_translator<Type>,Type>::type boost::property_tree::basic_ptree<Key,Data>::get_value(const Type &) const' : expects 1 arguments - 2 provided 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1> p:\cpp\boost\include\boost-1_42\boost\property_tree\ptree.hpp(336) : see declaration of 'boost::property_tree::basic_ptree<Key,Data>::get_value' 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1>p:\cpp\boost\include\boost-1_42\boost\property_tree\detail\ptree_implementation.hpp(655) : error C2784: 'boost::enable_if<boost::property_tree::detail::is_character<Ch>,std::basic_string<Ch>>::type boost::property_tree::basic_ptree<Key,Data>::get_value(const Ch *,Translator) const' : could not deduce template argument for 'const Ch *' from 'const std::basic_string<_Elem,_Traits,_Ax>' 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1> and 1> [ 1> _Elem=char, 1> _Traits=std::char_traits<char>, 1> _Ax=std::allocator<char> 1> ] 1> p:\cpp\boost\include\boost-1_42\boost\property_tree\ptree.hpp(328) : see declaration of 'boost::property_tree::basic_ptree<Key,Data>::get_value' 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1>p:\cpp\boost\include\boost-1_42\boost\property_tree\detail\ptree_implementation.hpp(655) : error C2780: 'Type boost::property_tree::basic_ptree<Key,Data>::get_value(void) const' : expects 0 arguments - 2 provided 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1> p:\cpp\boost\include\boost-1_42\boost\property_tree\ptree.hpp(313) : see declaration of 'boost::property_tree::basic_ptree<Key,Data>::get_value' 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1>p:\cpp\boost\include\boost-1_42\boost\property_tree\detail\ptree_implementation.hpp(655) : error C2780: 'boost::enable_if<boost::property_tree::detail::is_translator<Translator>,Type>::type boost::property_tree::basic_ptree<Key,Data>::get_value(Translator) const' : expects 1 arguments - 2 provided 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1> p:\cpp\boost\include\boost-1_42\boost\property_tree\ptree.hpp(306) : see declaration of 'boost::property_tree::basic_ptree<Key,Data>::get_value' 1> with 1> [ 1> Key=std::string, 1> Data=DataHold 1> ] 1>Build Time 0:05 1>Build log was saved at "file://p:\cpp\DebugServerLib\DebugServerLib\Debug\BuildLog.htm" 1>DebugServerLib - 7 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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A MPL loop..
by Frank Winter 11 Jul '10

11 Jul '10

I am trying to translate this runtime loop while( totalsize * maxelem * 3 > poolsize ) maxelem >>= 1; into MPL. I got so far: template< typename totalsize , typename maxelement , typename poolsize > struct loop { typedef mpl::times< totalsize , maxelement > part0; typedef mpl::times< part0 , mpl::int_< 3 > > part1; typedef mpl::greater< part1 , poolsize > gr; typedef mpl::if_< gr , typename loop< totalsize , mpl::divides< maxelement , mpl::int_< 2 > > , poolsize >::value , maxelement > value; }; template< class totalsize , class poolsize > struct loop< totalsize , mpl::int_< 1 > , poolsize > { typedef mpl::int_< 1 > value; }; typename loop< mpl::int_< 144 > , mpl::int_< 1024 > , mpl::int_< 140000 > > ::value max; g++43 (GCC) 4.3.2 says: error: template instantiation depth exceeds maximum of 500 If coded it correctly that should not happen. Since maxelement is already after the 1st interation mpl::int_< 512 > and therefor the product with mpl::int_< 144 > smaller than mpl::int_< 140000 > I could imagine: - that I need a constructor that converts the divided types, correct? - that I need to use a vector< sequence > like in the physics dimension example, correct? Can somebody fix this or point me to a working loop example? Regards, Frank

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bjam cross compile linking with wrong libs
by Mark Freeman 11 Jul '10

11 Jul '10

Hi, I'm trying to cross compile a simple program using libtorrent but falling foul of some settings in the boost build system. I am totally green at using boost so please excuse me if the answer is obvious. The problem is that the link line emitted by the boost build system appears to include a hard coded reference to a NATIVE lib (/usr/lib/ libdl.so) and not the one for the TARGET build system. Below is the output from the bjam command: BOOST_ROOT = /projects/externals/libtorrent/boost_1_43_0 OS = LINUX gcc.link bin/gcc-arm/debug/boost-source/link-static/threading-multi/ enum_if "${CROSS_COMPILE}gcc" -Wl,-R -Wl,"/usr/lib" -o "bin/gcc-arm/ debug/boost-source/link-static/threading-multi/enum_if" -Wl,--start- group "bin/gcc-arm/debug/boost-source/link-static/threading-multi/ enum_if.o" "../bin/gcc-arm/debug/boost-source/link-static/threading- multi/libtorrent.a" "/projects/externals/libtorrent/boost_1_43_0/ bin.v2/libs/thread/build/gcc-arm/debug/boost-source/link-static/ threading-multi/libboost_thread.a" "/projects/externals/libtorrent/ boost_1_43_0/bin.v2/libs/filesystem/build/gcc-arm/debug/boost-source/ link-static/threading-multi/libboost_filesystem.a" "/projects/ externals/libtorrent/boost_1_43_0/bin.v2/libs/system/build/gcc-arm/ debug/boost-source/link-static/threading-multi/libboost_system.a" "/ usr/lib/libdl.so" -Wl,-Bstatic -lssl -lcrypto -Wl,-Bdynamic -lrt - Wl,--end-group -g -pthread -export-dynamic /usr/lib/libdl.so: could not read symbols: File in wrong format collect2: ld returned 1 exit status ...failed updating 1 target... (CROSS_COMPILE has been set to the prefix for the toolset) I did add a <linkflags> entry to the GCC entry in usr-config.jam and sure enough this did appear in the emitted link line however /usr/lib was still there too and seemed to take precedence. Does anyone know what I have to do to remove this? Cheers, Mark.

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