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online change of iostream filter
by Daniel Oberhoff 08 May '08

08 May '08

I was wondering if it is possible to change the filter used to write to or read form a file without closing/reopening the file? The usecase is reading/writing matlab files, which contain zipped blocks within a context of unzipped data. So I would need to be able to switch on compression once such a block starts and switch off afterwards, and it would be nice not to have to ftell/close/create appropriate stream/open/ fseek every time. Best Daniel

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[preprocessor] Strange BOOST_PP_CAT behavior
by Sergey Sadovnikov 08 May '08

08 May '08

Hello All, Compilator: VC++ 8.0 Library version: 1.34 I can't understand problem with code like this: #define SOME_SEQ (1)(2)(3) #define BAR_MACRO_1(S) BOOST_PP_SEQ_ENUM(BOOST_PP_SEQ_TAIL(S)) #define FOO_MACRO(S) BOOST_PP_CAT(BAR_MACRO_, BOOST_PP_SEQ_HEAD(S) ## (S)) FOO_MACRO(SOME_SEQ) After preprocessing it looks like BOOST_PP_CAT(BOOST_PP_SEQ_ENUM_, BOOST_PP_CAT(BOOST_PP_SEQ_SIZE_, BOOST_PP_SEQ_SIZE_2)) (2)(3) If I replace BOOST_PP_CAT with my own macro: #define MY_CAT(a, b) MY_CAT_I(a, b) #define MY_CAT_I(a, b) a ## b Everything is all right after preprocessing: 2, 3 Why? What is wrong? -- Best Regards, Sergey mailto:flex_ferrum@artberg.ru

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asio::deadline_timer irregular behavior after async_wait
by Sharad Mittal 08 May '08

08 May '08

Can asio::deadline_timer be "reused" after its original wait has been completed? I am seeing irregular behaviour around resetting already expired timers - sometimes they fail to function. I am resetting the timer by using expires_from_now method. (Boost 1.34.1 with asio 0.3.9) Thanks, Sharad

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More general views with multi_array
by ALiX 08 May '08

08 May '08

Hi, Is there a way to create more general views of a multi_array than using start- and finish-indexes together with a stride? For example, I would like to create a view of a 2-dimensional multi_array by explicitly choosing the indexes: For a 10x10 matrix A, I want to be able to specify a 3x3 view with first dimension indexes 2,3,8 and second dimension indexes 5,6,9. For this example my_view[0][0] would access the element A[2][5], and my_view[1][2] would access element A[3][9]. Is this possible? An idea would be to write my own index_range class. But there is no index_range concept as far as I can tell... /ALiX

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How to load a Boost ublas matrix of size more than 50000 x 500?
by ajay gopalakrishnan 08 May '08

08 May '08

Hi all, I am unable to initialize a matrix of size 50000 x 500 using ublas::matrix<float>. I think it is giving error because no contiguous memory is available to create. But is there a way to create a non-contiguous matrix ? Thanks, Ajay G.

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Boost serialization: how to register template derived class
by ari vol 08 May '08

08 May '08

Hey, Boost serialization: how to register template derived class. The problem in general: I have the following classes: - Virtual based class: class TemplateBase { } - Derived class: template <class KUKU, int KUKUINT> class KukuBase : public TemplateBase{ } And I am trying to serialize the derived class KukuBase<KUKU, KUKUINT>through a pointer of the base type (polymorphism…). The problem is that I can not find a way to register the class KukuBase<KUKU, KUKUINT> and thus get unregistered_class exception. How to make it works? The cpp file: #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> // Serialization #include <boost/serialization/string.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/access.hpp> #include <boost/serialization/base_object.hpp> #include <boost/serialization/serialization.hpp> #include <boost/serialization/export.hpp> #include <fstream> class TemplateBase { public: TemplateBase() : mI(0) {} virtual TemplateBase* Clone() = 0; int mI; private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & mI; } }; template <class KUKU, int KUKUINT> class KukuBase : public TemplateBase { public: KukuBase() : mZ(1) {} TemplateBase* Clone() { return new KukuBase<KUKU, KUKUINT>(*this); } private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & boost::serialization::base_object<TemplateBase>(*this); ar & mZ; } float mZ; }; class foo { public: foo() : mT(new KukuBase<int, 5>) {}; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & mT; } TemplateBase* mT; }; BOOST_CLASS_EXPORT(foo); //BOOST_CLASS_EXPORT((KukuBase)); BOOST_CLASS_EXPORT(TemplateBase); int main() { std::ofstream ofs("/tmp/kuku"); boost::archive::text_oarchive ar(ofs); const foo bar; ar << bar; } The program returns: terminate called after throwing an instance of 'boost::archive::archive_exception' what(): unregistered class Abort And the stuck shows: (gdb) bt #0 0x000000000049e409 in kill () #1 0x0000000000470582 in abort () at ../sysdeps/generic/abort.c:88 #2 0x0000000000461bf8 in __gnu_cxx::__verbose_terminate_handler () #3 0x000000000045e216 in __cxxabiv1::__terminate () #4 0x000000000045e243 in std::terminate () #5 0x000000000045e343 in __cxa_throw () #6 0x000000000040190c in boost::throw_exception<boost::archive::archive_exception> () #7 0x00000000004015e1 in boost::archive::detail::save_pointer_type<boost::archive::text_oarchive, TemplateBase*>::polymorphic<TemplateBase>::save () #8 0x000000000040152d in boost::archive::detail::save_pointer_type<boost::archive::text_oarchive, TemplateBase*>::save<TemplateBase> () #9 0x000000000040142e in boost::archive::detail::save_pointer_type<boost::archive::text_oarchive, TemplateBase*>::invoke () #10 0x00000000004013aa in boost::archive::save<boost::archive::text_oarchive, TemplateBase*> () #11 0x0000000000401344 in boost::archive::basic_text_oarchive<boost::archive::text_oarchive>::save_override<TemplateBase* const> () #12 0x00000000004012e8 in boost::archive::detail::interface_oarchive<boost::archive::text_oarchive>::operator<< <TemplateBase* const> () #13 0x0000000000401299 in boost::archive::detail::interface_oarchive<boost::archive::text_oarchive>::operator&<TemplateBase*> () #14 0x000000000040124c in foo::serialize<boost::archive::text_oarchive> () #15 0x0000000000401197 in boost::serialization::access::serialize<boost::archive::text_oarchive, foo> () #16 0x0000000000401107 in boost::serialization::serialize<boost::archive::text_oarchive, foo> () #17 0x0000000000400f83 in boost::serialization::serialize_adl<boost::archive::text_oarchive, foo> () #18 0x00000000004022c6 in boost::archive::detail::oserializer<boost::archive::text_oarchive, foo>::save_object_data () #19 0x0000000000405c59 in boost::archive::detail::basic_oarchive_impl::save_object () #20 0x0000000000400d43 in boost::archive::detail::save_non_pointer_type<boost::archive::text_oarchive, foo>::save_standard::invoke () #21 0x0000000000400c6f in boost::archive::detail::save_non_pointer_type<boost::archive::text_oarchive, foo>::invoke () #22 0x0000000000400aff in boost::archive::save<boost::archive::text_oarchive, foo> () #23 0x0000000000400a38 in boost::archive::basic_text_oarchive<boost::archive::text_oarchive>::save_override<foo const> () #24 0x000000000040090e in boost::archive::detail::interface_oarchive<boost::archive::text_oarchive>::operator<< <foo const> () #25 0x0000000000400423 in main () (gdb) Quit Thanks,-Ariella ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

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[mpl] print metafunction
by Edward Diener 08 May '08

08 May '08

The "C++ Template Programming" book mentions an mpl::print metafunction in order to generate a warning diagnostic message. The Boost online documentation appears to be missing any message of this metafunction. Is this an error in the book or an error in the documentation ? If this metafunction does exist, what header file is it in ?

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[parameter::python] error compiling optional arguments with VC8
by "Jörg Wintner" 08 May '08

08 May '08

Hi all, trying to compile one of the simplest examples in the doc (see code below) for the python-binding of boost::parameters using Visual Studio 2005 prof, I get the following error: error C2440: 'initializing' : cannot convert from 'const boost::parameter::aux::use_default_tag' to 'unsigned int' ...\boost_1_35_0\boost\parameter\aux_\maybe.hpp on line 59 boost::python works well in binding non-boost::parameter-functions. Also, "boost_1_35_0\libs\parameter\test\python_test.cpp" compiles without errors. When all parameters of window::open(..) are set as being 'required' instead of 'optional', the code below finally compiles, too. Somebody, please give me a hint, I don't know where to start. Thanks in advance! /* from: http://www.boost.org/doc/libs/1_35_0/libs/parameter/doc/html/python.html */ #include <boost/parameter/keyword.hpp> #include <boost/parameter/preprocessor.hpp> #include <boost/parameter/python.hpp> #include <boost/python.hpp> BOOST_PARAMETER_KEYWORD(tag, title) BOOST_PARAMETER_KEYWORD(tag, width) BOOST_PARAMETER_KEYWORD(tag, height) class window { public: BOOST_PARAMETER_MEMBER_FUNCTION( (void), open, tag, (required (title, (std::string))) (optional (width, (unsigned), 400) (height, (unsigned), 400)) ) { } }; struct open_fwd { template <class A0, class A1, class A2> void operator()( boost::type<void>, window& self , A0 const& a0, A1 const& a1, A2 const& a2 ) { self.open(a0, a1, a2); } }; BOOST_PYTHON_MODULE(my_module) { using namespace boost::python; namespace py = boost::parameter::python; namespace mpl = boost::mpl; class_<window>("window") .def( "open", py::function< open_fwd , mpl::vector< void , tag::title(std::string) , tag::width*(unsigned) , tag::height*(unsigned) > >() ); } -- GMX startet ShortView.de. Hier findest Du Leute mit Deinen Interessen! Jetzt dabei sein: http://www.shortview.de/?mc=sv_ext_mf@gmx

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regex lib for Windows Mobile
by Freeman Ng 07 May '08

07 May '08

I'm trying to get the regex library (Boost ver. 1.34.1) working under Visual Studio 7.0 and the Windows Mobile 6 SDK, and have run into the following problems: 1. Need to modify visualc.hpp to define BOOST_NO_STD_LOCALE and BOOST_NO_SWPRINTF. 2. WM6 runtime library doesn't have strxfrm() or wcsxfrm(). 3. regex lib makes direct calls to ansi versions of CreateFile(), LoadLibrary(), FindFirstFile(), and others (i.e. CreateFileA(), etc.) that don't exist on the WM platform. 4. w32_regex_traits.cpp has a pragma that links directly to a library that doesn't exist for WM. (user32.lib) #1 is normal and trivial, of course, but before I tackle #2 and #3 by either writing my own versions of the missing functions or modifying the regex source, and #4 by modifying the regex source (which I really hate to do, but I can't think of any other way around this one) I want to make sure I didn't miss anything. Is there some combination of #defines or project settings that should allow the library to build for VS 7 Windows Mobile? Am I about to do more work than I need to? Thanks. Freeman

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Building Boost with VC9 and VC8
by Haroon Khan 07 May '08

07 May '08

Hi, I have visual studio 2005 and visual studio 2008 installed on my machine, and I would like to build Boost only with Visual Studio 2005 If I use the following command, bjam --toolset=msvc ... and it only builds libboost-<libname>-vc9-mt.lib or .dll If I use the folllowing command bjam --toolset=msvc-80 ... it builds libraries it without specifying the version number of Visual C++ compiler, eg. libboost-<libname>-vc-mt.lib. My environment is set to use the compiler for VC8. So far the workaround I've found is to uninstall Visual Studio 2008, Build Boost with Visual Studio 2005. Reinstall Visual Studio 2008. Any ideas on how to avoid this? Thanks, Haroon

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