February 2009 - Boost-users - lists.preview.boost.org

[archive]: Problem with creating a C-Interface DLL using Serialization/Archive
by von Arx, Martin 26 Feb '09

26 Feb '09

I'm writing a DLL which uses Boost for the Serialization (version 1.36.0). Because it has to maintain in different system I want to maintain a pure C-Interface DLL. As soon as I use the Boost-Library by activating the two lines boost::archive::text_iarchive ia(is); ia >> foo; in the function CNwDeSerialize_Test( ) it's C++ Interface becomes exposed in my C-Interface. Anybody got an idea why and what I can do to prevent it ? Regards Martin //===================================================== // Modul: stdafx.h #include <boost/archive/tmpdir.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/serialization/base_object.hpp> #include <boost/serialization/utility.hpp> #include <boost/serialization/list.hpp> #include <boost/serialization/assume_abstract.hpp> #include <boost/shared_ptr.hpp> //===================================================== // Modul: ChannelNwManager.h // ChannelNwManager.h : Defines the exported functions for the DLL application. // #ifdef __cplusplus extern "C" { #endif #ifdef CHANNELNWMANAGER_EXPORTS #define CHNNWMANAGER_API extern "C" __declspec(dllexport) #else #define CHNNWMANAGER_API extern "C" __declspec(dllimport) #endif CHNNWMANAGER_API void CNwDeSerialize_Test( void ); #ifdef __cplusplus } #endif //===================================================== // Modul: ChannelNwManager.cpp #include "stdafx.h" extern "C" __declspec(dllexport) void CNwDeSerialize_Test( ) { int foo; std::istringstream is("1"); // boost::archive::text_iarchive ia(is); // ia >> foo; } // ===================================================== // Modul: ChannelNwManager.cpp #include "stdafx.h" extern "C" __declspec(dllexport) void CNwDeSerialize_Test( ) { int foo; std::istringstream is("1"); boost::archive::text_iarchive ia(is); ia >> foo; }

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problems building with boost filesystem on Solaris 9
by Guy LaCrosse 26 Feb '09

26 Feb '09

here is my make file # Makefile for tpg5webapp CC=g++ CFLAGS = -static -m32 -fPIC -Wall BOOSTINC = -I/export/home/mlacrosse/boost/include/boost-1_38 STATIC_LIB_OPT = -Wl,"-Bstatic" LINK_OPTS = -v -fident -Wl,"-Bdirect" -Wl,"-m" -z defs -z rescan BOOST_LIBPATH = -L/export/home/mlacrosse/boost/lib/ -lboost_filesystem-gcc34-mt -lboost_system-gcc34-mt BOOST_LIBS = $(STATIC_LIB_OPT) $(BOOST_LIBPATH) TNLIBS = -L/export/home/jshelly/work/tserve4/lib TNINCLUDE = -I/export/home/jshelly/work/tserve4/pub/include BASE_LIBS= -L/usr/local/lib LOCALLIB = -L/export/home/mlacrosse/work/gccroot/usr/local/lib INCLUDES = -I. -I./h $(BOOSTINC) $(TNINCLUDE) LIBS = $(BOOST_LIBS) $(TNLIBS) $(BASE_LIBS) $(LOCALLIBS) DEFINES = -D__SOLARIS__ -DBSD_COMP -DSTRICT_PROTO -DSSBIGENDIAN all: tpg5webapp tpg5webapp: tpg5webapp.cpp ConfigFile.cpp $(CC) $(CFLAGS) $(DEFINES) $(INCLUDES) $(LIBS) \ -o tpg5webapp ConfigFile.cpp tpg5webapp.cpp run: tpg5webapp ./tpg5webapp | tee tpg5webapp.out tidy: @ rm -f *.o clean: tidy @ rm -f tpg5webapp tpg5webapp.out core* here are the error message that I'm getting Undefined first referenced symbol in file boost::filesystem::detail::dir_itr_first(void*&, void*&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, boost::filesystem::file_status&, boost::filesys tem::file_status&)/var/tmp//ccOQOOR8.o boost::system::get_generic_category() /var/tmp//ccOQOOR8.o boost::filesystem::detail::dir_itr_increment(void*&, void*&, std::basic_string<char, std::char_traits<char>, std::allocator<char > >&, boost::filesystem::file_status&, boost::filesystem::file_status&)/var/tmp//ccOQOOR8.o boost::system::get_system_category() /var/tmp//ccOQOOR8.o boost::filesystem::detail::not_found_error() /var/tmp//ccOQOOR8.o boost::filesystem::detail::symlink_status_api(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, boo st::system::error_code&)/var/tmp//ccOQOOR8.o boost::filesystem::detail::remove_api(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)/var/tmp//cc OQOOR8.o boost::filesystem::detail::create_directory_api(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)/v ar/tmp//ccOQOOR8.o boost::filesystem::detail::dir_itr_close(void*&, void*&)/var/tmp//ccOQOOR8.o boost::filesystem::detail::copy_file_api(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::bas ic_string<char, std::char_traits<char>, std::allocator<char> > const&)/var/tmp//ccOQOOR8.o boost::filesystem::detail::status_api(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, boost::syst em::error_code&)/var/tmp//ccOQOOR8.o boost::filesystem::detail::get_current_path_api(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)/var/tmp //ccOQOOR8.o ld: fatal: Symbol referencing errors. No output written to tpg5webapp collect2: ld returned 1 exit status make: *** [tpg5webapp] Error 1

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Some questions about cross-compiling boost
by 磊周 26 Feb '09

26 Feb '09

Hi,everyone. The version of boost I used is 1.38. I have tried to cross-compile the boost library for a platform with ARM and Linux, but I failed. What I did is listed following: #cd mypath/boost_1_38_0/tools/jam/src #./build/build.sh By doing these, I got a executable file named bjam in the folder "bin.linuxx86". I copied the bjam to the directory "mypath/boost_1_38_0/", then : #cd mypath/boost_1_38_0 #./bjam "-sGCC_ROOT_DIRECTORY=/opt/mv_pro_4.0/montavista/pro/devkit/arm/v5t_le" "-sGCC=arm_v5t_le-gcc" "-sGXX=arm_v5t_le-g++" "-sGCC_BIN_DIRECTORY=/opt/mv_pro_4.0/montavista/pro/devkit/arm/v5t_le/bin" finally, there were some libraries gengerated in "usr/local/lib". Unfortunately, these libraries just can be used in the X86 platform but not ARM platform. Maybe my method was incorrect. Could anyone give me some advices to deal with my problem? Thanks! Best wishes Zou ___________________________________________________________ 好玩贺卡等你发，邮箱贺卡全新上线！ http://card.mail.cn.yahoo.com/

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shared_ptr and global reset
by Matthieu Guillo 26 Feb '09

26 Feb '09

Hi Boosters Let's say that I have many shared_ptr<A> sharing ownership to the same A object. At some point, I would like all those shared_ptr to point to a new Object A. Is there an easy (and safe) way to accomplish that? I know how to do that for one shared_ptr using either "reset", either operator = but in order to do this for all shared_ptr sharing ownership, the only way I could think of is through a registration mechanism (like the Observer pattern) but this sounds an overkilling process to me. So basically, is there a "global" reset method? Thanks ------------------------------------------ Matthieu Guillo ------------------------------------------

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Re: [Boost-users] metafunction invocation performance
by Hicham Mouline 26 Feb '09

26 Feb '09

The solution to this one is provided by Joaquin, in his reply below: I tried compiling your code with MSVC++ 8.0 and it is indeed incredibly slow. After playing a little with the code I realized that MPL views are the culprit here: for some reason it is much faster to fold on a vector-based computation rather than a view: template<typename Sequence1,typename Sequence2> struct sequence_product : boost::mpl::fold< Sequence1, boost::mpl::vector0<>, boost::mpl::copy< boost::mpl::transform< Sequence2, pair_with<boost::mpl::_2> >, boost::mpl::back_inserter<boost::mpl::_1> > > {}; This transformation on sequence_product and seq_seqpair_product alone improved the performance tremendously. Additionally I've tried a small optimization: in seq_seqpair_product it is preumable better to fold on Sequence rather than SequencePair, since on average the first is expected to be shorter. Truth be said, I haven't detected any improvement with this, anyway. > Shouldn't there be a dot-product or cross-product of mpl sequences as > a general algorithm? and not just 2 sequences but N. I guess it is the O(n^2) behavior that deterred the author from including the algorithm (much as STL usually does not contain quadratic algorithms). It might be a worthy addition, nonetheless Joaquin --------- Interesting why a joint_view slower than the alternative. This result confirmed then on MSVC8 , gcc4.1, Intel10... regards, /Hicham

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Boost.IOStreams lzma support?
by anony 26 Feb '09

26 Feb '09

Is this going to be implemented? I might contribute some code if not. LZMA has amazing compression ratios.

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scoped_ptr::release (again)
by Yang Zhang 26 Feb '09

26 Feb '09

From http://www.boost.org/doc/libs/1_36_0/libs/smart_ptr/scoped_ptr.htm: "If scoped_ptr had a release() member, it would become possible to transfer ownership of the held pointer, weakening its role as a way of limiting resource lifetime to a given context. Use std::auto_ptr where transfer of ownership is required. (supplied by Dave Abrahams)" But there already is a way to escape the scope, via swap(). Would it make more sense to just provide release() and have users specify const if they want? (const scoped_ptr/scoped_array would effectively disallow swapping/releasing.) -- Yang Zhang http://www.mit.edu/~y_z/

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Boost; Default constructor work around.
by niranjan bangera 26 Feb '09

26 Feb '09

Hi, I need to know the information abt Constructor in my class to be serialized. What if i dont have defualt constructor in my class. Any other work around rather then putting the default construcor in my class, Pls Let me know if any workaround or doccumentaion. Boost: 1.38.0 ==== Compiler: ====== /_TOOLS_/dist/gnu-gcc-/4.1.1-binutils-2.16.1/x86_64-pc-linux2.4/bin/gcc class Myclass { Myclass (const string & a) { name=a; } private: int a; string name; //serialization code }; Thanks in Advance. Thanks, Niranjan

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[tuples][hash] How to make them work together ?
by Alexander 26 Feb '09

26 Feb '09

Is there an implementation of boost hash for tuples available in boost ?

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Boost.Thread annoyance
by anony 26 Feb '09

26 Feb '09

Just by including: "boost/thread.hpp", which includes "boost/bind.hpp" you pollute the namespace. If you also use Boost.Lambda, you must change _1 to boost::lambda::_1. Is this going to be fixed? Any workarounds?

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