February 2008 - Boost-users

boost lambda weirdness (possible bug?)
by David Sankel 04 Feb '08

04 Feb '08

Hello, I'm trying to use boost lambda to create a function<void (const T&)> and I can't seem to get it to work. Here's the setup: class T { public: char m_c; T( char c ) : m_c( c ) { } virtual T * clone() const=0; virtual ~T(){} }; typedef boost::shared_ptr<T> TPtr; typedef std::vector<TPtr> TVec; using namespace boost::lambda; This works: const boost::function< void( T const * const) > f = bind( &TVec::push_back, &tVec, bind( constructor<TPtr>(), bind( &T::clone, _1))); But this doesn't: const boost::function< void( const T & ) > g = bind( &TVec::push_back, &tVec, bind( constructor<TPtr>(), bind( &T::clone, boost::cref(_1) ))); The compilation error I'm getting is that it cannot create a new object of type T and that is expected since T is abstract. Why would lambda be making copies instead of passing on the reference? I've attached a simplified version of the problem. Thanks, David -- David Sankel Sankel Software www.sankelsoftware.com 585 617 4748 (Office) 585 309 2016 (Mobile)

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building boost doc
by Christian Henning 04 Feb '08

04 Feb '08

Hi there, I just have a general question about the building boost documentation. Right now when building the trunk by just using the toolset option only dynamically linked libs using the release version code are being built. To specify static linked one need to add link=static to the command line. Can someone tell where to find such information in the documentation? Same question goes for all other options that I can apply to command line, like debug builds, etc. Thanks, Christian

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How to get the full path name of a file
by Ha Ha 04 Feb '08

04 Feb '08

With leaf(), I would only get file name like 1.doc. How could I get the full path name of a certain like c:\windows\1.doc. Thanks Haha

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[Boost::Serialization] How to serialize a dynamic array within a class
by Chengyuan Ma 04 Feb '08

04 Feb '08

I have a class needs to be serialized into an XML file. I can save the object into an XML file, but i can not load it back. I found the problem is the dynamic array, "double *pMixtureWeight". What's the correct way to serialize a dynamic array into a XML file if i don't want to change it to a vector<double>? thx a lot! class Model { public: Model(); virtual ~Model() ; private: // serialization support friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int /* file_version */) { ar & boost::serialization::make_nvp("FeatureDim", FeatureDim) ; ar & boost::serialization::make_nvp("MixtureNum", NumMixtures) ; for(int ii = 0 ; ii < m_iNumMixtures; ii ++ ) { string tag = "weight_" + boost::lexical_cast<string>(ii + 1) ; ar & boost::serialization::make_nvp(tag.c_str(), pMixtureWeight[ii]) ; } } private: int FeatureDim; int NumMixtures; double *pMixtureWeight; };

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[Boost.Filesystem] Is there any bug in ofstream implementation ?
by Marc Viala Perso 02 Feb '08

02 Feb '08

Hi, I not pretty sure but it seems that there is a bug (?) somewhere in boost::filesystem::ofstream implementation in the Boost 1.34.1 release; to exhibit this behaviour, the snippet code hereafter trigger an assert in the last block: int main(int /*argc*/, char* /*argv[]*/) { const fs::path p("c:/temp/test.txt") ; const fs::wpath wp(L"c:/temp/test.txt") ; { fs::remove(p) ; fs::ofstream ofile(p) ; assert(!ofile.fail()) ; } { fs::remove(p) ; fs::ofstream ofile(wp) ; assert(!ofile.fail()) ; } { fs::remove(p) ; fs::ofstream ofile(p, std::ios_base::binary) ; assert(!ofile.fail()) ; } { fs::remove(p) ; fs::ofstream ofile(wp, std::ios_base::binary) ; assert(!ofile.fail()) ; // <-- Assert triggered here } } Running conditions: Boost 1.34.1 Visual C++ 7.1 Windows XP I'm waiting for your feedback. Best regards, Marc VIALA

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building boost libraries with VS2008 (VC9)
by Prashant Gupta 02 Feb '08

02 Feb '08

I have both VS2005 (VC8) and VS2008 (VC9) on the same machine. I have already downloaded 'boost_1_34_1.zip' and installed a complete boost distribution. On the command prompt, I go to $BOOST_ROOT and type just "bjam", with no arguments. I get the complete VC8 build in a clean way. I follow the same procedure to build using VS2008 (vc9). I go to the $BOOST_ROOT and type "bjam --toolset=msvc-9.0 stage". I get bunch of errors, resulting in failure. Could someone help me in building clean boost libraries, using VS2008 (VC9)?

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[Boost Interprocess] - Windows 64-bit / 32-bit mixed process support
by Richard Brown 01 Feb '08

01 Feb '08

Ion, I have a server process and multiple client processes which successfully share a managed_shared_memory vector as well as two message_queues. All processes are 32-bit, and run under both Windows XP and 64-bit XP Server (using 32-bit Wow emulation). However I am trying to take advantage of the Windows XP 64-bit OS, so I have attempted to build the Server process as 64-bit, while leaving the client processes at 32-bit (unfortunately I'm stuck with some 32-bit libraries and cannot move the client processes to x64 at this time). Both the server and clients (64 bit and 32 bit respectively) can see the shared memory file that Interprocess creates, and my class members use fixed-sized datatypes (__int32, __int64), but after walking some of the code it became apparent that Interprocess is having issues with mixing the different processes. Example: message_queue::do_receive(block_t block, void *buffer, std::size_t buffer_size, std::size_t &recvd_size, unsigned int &priority, const boost::posix_time::ptime &abs_time) ... ... //Thre is at least message ready to pick, get the top one detail::msg_hdr_t *top_msg = p_hdr->top_msg(); //Paranoia check if (top_msg == 0) { throw interprocess_exception(); } //Get data from the message recvd_size = top_msg->len; priority = top_msg->priority; ... ... The contents of top_msg appear to be "shifted", such that "top_msg->len;" now returns a 0. Obviously much of this is due to std::size_t being sized differently on the server process (at 64-bit) vs. the client (32-bit) processes. II thought of doing a bit of experimentation, whereby I could replace all instances of std::size_t in the library with something windows specific - like "unsigned __int64", but I have no idea if variations in data type size are the only issue. Should I give it a try or perhaps a different approach would be better? Thanks, Rich Brown if (Nabble.searchterms != null && Nabble.searchterms.length > 0) { Nabble.hilt(Nabble.searchterms, Nabble.get("nabble.msgtxt15191825")); }  //Nabble.gquery = 'test'; //Nabble.topicDumpSearch = true; if (Nabble.gquery!=null) { if (Nabble.topicDumpSearch) { Nabble.get('nabble.searchResults').innerHTML = '<h1> Other threads matching \"<strong>'+Nabble.gquery+'</strong>\":</h1>'+ '<p style=\"margin-left: 3em;\">looking for matching threads...</p>'; Nabble.loadScript('/forum/TopicDump$SearchJs.jtp?query='+encodeURIComponent(Nabble.gquery)+'&post=15191825'); Nabble.setVar('prev',null); } else { Nabble.setVar('prev', '<big><a id="nabble.prev_search" href="/forum/Search.jtp?query='+encodeURIComponent(Nabble.gquery)+'">Search Nabble for "<b>'+Nabble.gquery+'</b>"</a>' ); } } if( Nabble.prev ) Nabble.writeReturnToLink(Nabble.prev);

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Howto bind with string_algo predicates on gcc?
by Jean-Pierre Bergamin 01 Feb '08

01 Feb '08

Hello everyone I ran into an issue I cannot explain, when using bind with the string algorithms. The following code fragment works as expected with MSVC 8.0: #include <boost/algorithm/string/predicate.hpp> #include <boost/bind.hpp> #include <iostream> #include <vector> #include <string> using namespace std; using namespace boost; using namespace boost::algorithm; int main() { typedef vector<string> string_container; string_container numbers; numbers.push_back("one"); numbers.push_back("two"); numbers.push_back("three"); string_container::const_iterator s = find_if(numbers.begin(), numbers.end(), bind(&contains<string, string>, _1, "w")); if (s != numbers.end()) { cout << "Found: " << *s << endl; } return 0; } Trying to compile the same code with gcc 3.4.5 gives the error: test.cpp:18: error: no matching function for call to `bind(<unknown type>, boost::arg<1> (&)(), const char[2])' Does anyone has an idea how to let bind know the "type" of the predicate "contains"? Regards Jean-Pierre Bergamin

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type trait for detecting unsigned integer
by Stephen Torri 01 Feb '08

01 Feb '08

Is there a way to detect a unsigned integer? I would like to have a template to replace a macro that checks a value is in a range. Here is what I have so far: template <typename Limit_Type> static inline void in_range ( boost::uint32_t value, Limit_Type limit ) { if ( value > limit ) { throw errors::Internal_Exception ( errors::Internal_Exception::INVALID_VALUE ); } } I would like to replace the "boost::uint32_t" with a default typename and check to see if the 'value' is an unsigned type. Stephen

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Boost.Utility/Singleton Problem when using with dynamic libraries
by NFarnsworth＠web.de 01 Feb '08

01 Feb '08

Hello, I want to use the Boost.Utility/Singleton together with dll's. I use the Visual Studio 2005 and Windows XP. I have three dynamic libraries. In library A the Singleton is implemented and library B and C access to the Singleton. The dynamic libraries B and C are compiled with the clr compiler Option. The Problem is, that the Singleton will be twice instantiated when library A and B access to the singleton. The singleton declaration looks like the following code: //Singleton.h class Singleton : public boost::singleton<Singleton ,1,factorylib_tag > { public: CPP_API Singleton (boost::restricted); … BOOST_SINGLETON_PLACEMENT_DECLARATION … } CPP_API is a definition of the dll export. #if defined( _WIN32 ) && defined( _MSC_VER ) # if defined SINGLETON_EXPORTS # define CPP_API __declspec( dllexport ) # else # define CPP_API __declspec( dllimport ) # pragma warning( disable : 4251 ) // 'identifier' : class 'type' needs to have dll-interface to be used by clients of class 'type2' # endif #endif In the Project properties of library B and C in "additional linkage input" I included the import library of the dll A. Another problem is, that the application crashes when I close the application. The crash happens in C.dll!_CRT_INIT(void * hDllHandle=0x0f8b0000, unsigned long dwReason=0, void * lpreserved=0x00000001) line 420 -> _free_crt ( onexitbegin ) ; And also : B.dll!_CRT_INIT(void * hDllHandle=0x0f8b0000, unsigned long dwReason=0, void * lpreserved=0x00000001) line 420 -> _free_crt ( onexitbegin ) ; If I don't use the singleton, the application will not crash. Another Problem is, that I can not compile the following code: class DataPoolManagerImpl : public boost::mutexed_singleton<DataPoolManagerImpl,2,datapoollib_tag> { Then I will get the following error message: boost\utility\mutexed_singleton.hpp(212) : error C2248: "boost::mutexed_singleton<Derived,DisposalSlot>::instance_proxy": cannot access private class, which is declared in boost::mutexed_singleton<Derived,DisposalSlot> with [ Derived=DataPoolManagerImpl, DisposalSlot=2 ] \boost\utility\mutexed_singleton.hpp(41): see declaration of 'boost::mutexed_singleton<Derived,DisposalSlot>::instance_proxy' with [ Derived=DataPoolManagerImpl, DisposalSlot=2 ] \boost\utility\mutexed_singleton.hpp(211): During compiling the class template of the static data member "const boost::mutexed_singleton<Derived,DisposalSlot,SubsystemTag>::instance_proxy boost::mutexed_singleton<Derived,DisposalSlot,SubsystemTag>::instance". with [ Derived=DataPoolManagerImpl, DisposalSlot=2, SubsystemTag=datapoollib_tag ] \datapoolmanager.h(43): see reference of instantiation of compiled class template "boost::mutexed_singleton<Derived,DisposalSlot,SubsystemTag>". with [ DataPoolManagerImpl, DisposalSlot=2, datapoollib_tag ] \boost\utility\mutexed_singleton.hpp(212) : error C2440: Initialization': 'boost::mutexed_singleton<Derived,DisposalSlot>::instance_proxy' could not converted in 'boost::mutexed_singleton<Derived,DisposalSlot,SubsystemTag>::instance_proxy' with [ Derived=DataPoolManagerImpl, DisposalSlot=2 ] With : class DataPoolManagerImpl : public boost::singleton<DataPoolManagerImpl,2,datapoollib_tag> There are no compiler errors. Could you tell me how I can solve these problems please? Thank you for your help in advance and best regards Niklas _____________________________________________________________________ Unbegrenzter Speicherplatz für Ihr E-Mail Postfach? Jetzt aktivieren! http://www.digitaledienste.web.de/freemail/club/lp/?lp=7

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