February 2008 - Boost-users

Re: [Boost-users] Boost.Utility/Singleton Problem when using with dynamic libraries
by NFarnsworth＠web.de 07 Feb '08

07 Feb '08

Hello, Unfortunately I still need help with these problems please. Is there anybody who could explain me how to use the Boost.Utilty/Singleton with dlls? The test examples of the singleton didn't clearify for me, how I can do this. Best regards Niklas > > 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 _______________________________________________________________________ Jetzt neu! Schützen Sie Ihren PC mit McAfee und WEB.DE. 30 Tage kostenlos testen. http://www.pc-sicherheit.web.de/startseite/?mc=022220

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[function] How to obtain the signature type?
by Robert Dailey 07 Feb '08

07 Feb '08

Hi, Currently I have the following: typedef boost::function<void (int)> MyFunction; Is there a typedef in the boost::function class for the Signature template parameter? I need access to the function type passed into the boost::function object. I've tried finding the boost::function class in the source, but that turned out to be impossible. The documentation also does not explain how to do this from what I saw. Any help is appreciated.

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[flyweight][review] Flyweight accepted
by Ion Gaztañaga 07 Feb '08

07 Feb '08

Hi to all, The Flyweight library submitted by Joaquín M. López Muñoz has been *accepted* into Boost. Thanks to all reviewers and all who contributed to the library before the review. We've received 10 reviews (Alberto Ganesh Barbati, David Sankel, John Reid, John Torjo, Kevin Scopp, Marcus Lindblom, Markus Werle, Matias Capeletto, Neil Hunt, Tim Blechmann), and all except Alberto's one were positive. Please, if I've missed a review, let me know. Joaquín agreed to address Alberto's comments (either with keyed_flyweight or by another method) and I like to encourage Joaquín and Alberto and the rest of the Boost community to improve the flyweight library to optimize and adapt it for situations like Alberto has described. I'm pretty sure that we'll reach an agreement. I'll have some time during the weekend to read all the reviews and write an small summary of requested changes, ideas, complaints, etc... to summarize the review process. Congratulations to Joaquín and thanks to all those who have participated in the review. Ion Gaztañaga - Review Manager -

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Saving to older version
by at forum 07 Feb '08

07 Feb '08

Hi I am testing boost serialization to integrate it in our software. Actually I am using mfc I want to save an object to an older version? I using the split method (save and load) and I don't find how to pass the version to the save function? "BOOST_SERIALIZATION_NVP(this)" is using the current object version. code : class CMyPoint { friend class boost::serialization::access; protected: int m_nX, m_nY; std::string m_sName; public: CMyPoint() { m_nX = 0; m_nY = 0; m_sName = ""; } CMyPoint(int nX, int nY, std::string sName = "") { m_nX = nX; m_nY = nY; m_sName = sName; } void SetX(int nX) { m_nX = nX; } void SetY(int nY) { m_nY = nY; } virtual void Assign(const CMyPoint &pt) { m_nX = pt.m_nX; m_nY = pt.m_nY; } CMyPoint& operator =(const CMyPoint &pt) { Assign(pt); return *this; } template<class Archive> void save(Archive & ar, const unsigned int version) const { ar & BOOST_SERIALIZATION_NVP(m_nX) & BOOST_SERIALIZATION_NVP(m_nY); if(2 <= version) ar & BOOST_SERIALIZATION_NVP(m_sName); } template<class Archive> void load(Archive & ar, const unsigned int version) { ar & BOOST_SERIALIZATION_NVP(m_nX) & BOOST_SERIALIZATION_NVP(m_nY); if(2 <= version) ar & BOOST_SERIALIZATION_NVP(m_sName); } BOOST_SERIALIZATION_SPLIT_MEMBER() void Save(const char * filename) { std::ofstream ofs(filename); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); oa << BOOST_SERIALIZATION_NVP(this); } void Load(const char * filename) { std::ifstream ifs(filename); assert(ifs.good()); boost::archive::xml_iarchive ia(ifs); ia >> BOOST_SERIALIZATION_NVP(this); } }; BOOST_CLASS_VERSION(CMyPoint, 2) BOOST_CLASS_EXPORT_GUID(CMyPoint, "CMyPoint") Thank you

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Linker error
by Robert Dailey 07 Feb '08

07 Feb '08

Hi, I'm using Visual Studio 9 on Windows. Up until I the inclusion of <boost/signals.hpp>, my application linked fine. Now I'm getting the following linker error: *LINK : fatal error LNK1104: cannot open file 'libboost_signals-vc90-mt-gd-1_35.lib' *Here is the order of my includes in my precompiled header: #include <boost/timer.hpp> #include <boost/function.hpp> #include <boost/noncopyable.hpp> #include <boost/shared_ptr.hpp> #include <boost/scoped_ptr.hpp> #include <boost/bind.hpp> #include <boost/array.hpp> #include <boost/xpressive/xpressive.hpp> #include <boost/signals.hpp>

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[BGL] Sorting Edges
by John Hood 07 Feb '08

07 Feb '08

Hello, all, Sorry to spam the list over this, but I my need is dire. In reading the boost::graph documentation, I stumbled across an example of sorting a graph's edges (I am trying to implement a bi-directional graph with edge-sorting). I have been searching through the docs, but to no avail. Could some kind soul point me in the right direction? Many thanks. -J

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MACRO to evaluate mpl::size::value as a constant.
by Tim St. Clair 06 Feb '08

06 Feb '08

Is there a MACRO which returns a constant when evaluating the size of an mpl sequence. Here is what I'm trying to do: #define MY_MACRO (N) CREATE_FOO_BAR_FN##N #define SUPERFUNK (CLASSA, ...)\ CLASSA { \ typedef mpl::vector<__VA_ARGS__> v0; \ MY_MACRO ( ??SOME_BOOST_MACRO??(mpl::size<v0>::value) ) \ } \ If seems like this should be possible given that I can do the following: BOOST_MPL_ASSERT_RELATION(mpl::size<v0>::value, ==, 0); -- Regards, Timothy St. Clair [timothysc(a)gmail.com]

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[graph] removing self-edges bug?
by Sebastian Weber 06 Feb '08

06 Feb '08

Hi everyone! I think I've hit a but in the remove_edge(u,v,bg) function in case I want to delete a self-edge. The following code crashes on my machine: using namespace boost; typedef adjacency_list<vecS, vecS, undirectedS > ubase_graph_t; ubase_graph_t bg(5); add_edge(0, 1, bg); add_edge(1, 2, bg); add_edge(3, 4, bg); add_edge(4, 0, bg); add_edge(2, 2, bg); remove_edge(2, 2, bg); However, deleting via edge_descriptors is working: BGL_FORALL_OUTEDGES(2, ed, bg, ubase_graph_t) { if(target(ed, bg) == 2) { remove_edge(ed, bg); break; } } So what is wrong with remove_edge(u, u, bg) if there is a self-edge? My boost version is 1.34.1 and I am using g++ 4.1.2 on an ubuntu gutsy machine. Some info from gdb, but the output is just not usable to me - I have no clue what happens: *** glibc detected *** ../build/tools/gcc/debug/revTest: free(): invalid next size (fast): 0x08085420 *** ======= Backtrace: ========= /lib/tls/i686/cmov/libc.so.6[0xb743bd65] /lib/tls/i686/cmov/libc.so.6(cfree+0x90)[0xb743f800] /usr/lib/libstdc++.so.6(_ZdlPv+0x21)[0xb7603d81] ../build/tools/gcc/debug/revTest[0x804f943] ../build/tools/gcc/debug/revTest[0x804f978] ../build/tools/gcc/debug/revTest[0x8050c7f] ../build/tools/gcc/debug/revTest[0x8050cbf] ../build/tools/gcc/debug/revTest[0x80510f3] ../build/tools/gcc/debug/revTest[0x8051180] ../build/tools/gcc/debug/revTest[0x8049b4b] /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe0)[0xb73e8050] ../build/tools/gcc/debug/revTest(__gxx_personality_v0+0x81)[0x80497b1] Greetings, Sebastian

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[boost.iostreams] Can't be able to read gzipped file
by Marc Viala Perso 06 Feb '08

06 Feb '08

Hello, During the implementation of a TARFILE module based on Boost.Iostream, I've faced a problem during reading operation of a boost::iostream::filtering_stream<> with a GZip codec. To illustrate it, you will find hereafter a small code snippet that reproduces my problem: namespace io = boost::iostreams ; namespace fs = boost::filesystem ; const fs::path test_file("test.txt.gz") ; const std::string s("Test..................") ; { io::filtering_stream<io::output> ofilter ; ofilter.push(io::gzip_compressor()) ; ofilter.push(io::file_descriptor_sink( test_file.external_file_string() , std::ios::binary)) ; ofilter << s ; } { io::filtering_stream<io::input> ifilter ; ifilter.push(io::gzip_decompressor()) ; ifilter.push(io::file_descriptor_source( test_file.external_file_string() , std::ios::binary)) ; std::string rs ; ifilter >> rs ; // <- Here process is blocked in file_description.cpp @ line 145 //boost::scoped_array<char> buffer(new char[512]) ; //const std::streamsize count = io::read(ifilter, buffer.get(), 512) ; } The problem occurs during the reading operation @ line: "ifilter >> rs": the process is blocked in boost/iostreams/src/file_description.cpp @ line 145 ("if (!::ReadFile(pimpl_->handle_, s, n, &result, NULL))") when this line is executed. I've tried to use boost::iostream::read() template function without more success. I've checked the file after the writing operation w/ 7z and everything is fine at this point. I've tried the same code snippet w/ ZLib and BZip2 codecs without trouble. My environment is: Visual C++ 7.1 Boost 1.34.1 Windows XP SP2 Is there any bug in GZip decompressor with the file_descriptor_source? Or I've missed something? Any help will be appreciated. Best regards, Marc VIALA

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Thread creation overhead & efficiency
by James Sutherland 06 Feb '08

06 Feb '08

I am a new user of boost::thread. After implementing it I found that it slowed down execution of my code. I suspect that it may be due to the overhead of thread creation. I am creating/destroying thread_group ojects many times (tens of thousands) during code execution. Pardon my naïve question, but is this a problem for performance? I noticed some reference to a thread pool on this list. Is a thread pool the best alternative in this situation? Thanks for any guidance, James

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