February 2008 - Boost-users - lists.preview.boost.org

BGL: Finding a vertex by the vertex_index_t property
by Torsten Sadowski 21 Feb '08

21 Feb '08

Hi, is there a simple possibility to find a vertex in a adjacency_list graph by the vertex_index_t property? My uninspired way would be to build a map<int, vertex_descriptor> but there might be something more elegant. Cheers, Torsten

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[variant] ideas needed
by ope 21 Feb '08

21 Feb '08

Hi, I've the following code: ---8<--- #include <boost/variant.hpp> #include <iostream> #include <string> struct available : public boost::static_visitor<bool> { template <typename T, typename U> bool operator()( const T&, const U& ) const { return false; // cannot compare different types } template <typename T> bool operator()( const T& lhs, const T& rhs ) const { static const std::string NA( "NA" ); return lhs != NA; //??? } }; using namespace boost; using namespace std; int main() { variant< double, std::string > R; variant< double, std::string > L; R = 3.14; L = "NA"; cout << R << endl; cout << L << endl; bool r = boost::apply_visitor(available(), R ); cout << ( r ? "true" : "false" ) << endl; bool l = boost::apply_visitor(available(), L ); cout << ( l ? "true" : "false" ) << endl; } --->8--- which does not compile. Anyway, from a data parser I get a double or a "NA" (not available) string. This test shall handle both cases. To process using the double I have to check if it available (than use defaults). Unfortunately, the static_visitor<bool> needs two arguments. How can I get the syntax (or simpler) as used in the example? Thanks Olaf

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A request for help using the Boost Unit Test Library
by Tim Allison 21 Feb '08

21 Feb '08

I am working on a project that uses the Boost Multi-Index library and Boost shared_ptr, so I know I can use the Boost libraries on our project. However, I am unable to build so much as an example from the Boost Unit Test Library, and need help. (I assume the problem is a conflict with compiler switches, or something along those lines.) I set up a test directory, into which I will link the source code I wish to test. The Make file I am using is a modified form of one we use to build my project, so I know it will build both the module using some Boost libraries, and our old code, some of which is more than 10 years old. I am using boost 1.33.1-42@586 on Suse 10.2 (If it matters, my computer is a Latitude D510) and Gnu compiler 4.1.3-29@586 (as listed by Smart Package Manager). When I run the make file, it echos out the following line: g++ -Wno-deprecated -frepo -m32 -g -I../lib -I/usr/X11R6/include -I../../../source/ecs/shared -DOS_IS_LINUX -c FuserTests.cc FuserTests.cc is the file into which I have attempted to copy the examples. (The examples are both from the patmedia.net/rogeeff site, and the official boost site, as corrected within the discussion forum.) The case I am most interested in running uses BOOST_AUTO_TEST_CASE( functionName ). This line produces the error: FuserTests.cc:16: error: expected constructor, destructor, or type conversion before ‘(’ token Is there something special I need to do to get this to compile in C++? -- Tim Allison Chief Engineer MIDCON Millennium Engineering and Integration (719) 264-4302 Work (719) 264-4318 Fax

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[has_xxx] How can it work at all???
by Ovanes Markarian 21 Feb '08

21 Feb '08

Hello *! As already asked many times in the list about the broken HAS_XXX ( BOOST_MPL_HAS_XXX_TRAIT_DEF<http://www.boost.org/libs/mpl/doc/refmanual/has-xxx-trait-def.html>) mpl I would like to ask following: If I use this code (on MSVC 7.1 compiler) and I have a type like: struct test { int xxx; }; and use the macro namespace x { BOOST_MPL_HAS_XXX_TRAIT_DEF(xxx); } This will result in the following code fragment: -------------------------------------------------------------------------------------------- /// included code from has_xxx.hpp namespace boost { namespace mpl { namespace aux { template< typename T > struct msvc71_sfinae_helper { typedef void type; }; } } } namespace sn { template< typename T, typename U = void > struct has_xxx_impl_ { static const bool value = false; typedef boost::mpl::bool_<value> type; }; template< typename T > struct has_xxx_impl_< T , typename boost::mpl::aux::msvc71_sfinae_helper< typename T::xxx >::type > { static const bool value = true; typedef boost::mpl::bool_<value> type; }; template< typename T, typename fallback_ = boost::mpl::bool_<false> > struct has_xxx : has_xxx_impl_<T> { }; } -------------------------------------------------------------------------------------------------- For me this will clearly fail, since T::xxx is not a type but an integer member of the struct. If xxx would be a member function it would not be a type as well, so has_xxx can only determine if there is some nested class type or a typedef within the inspected type. Is this correct? Many thanks, Ovanes

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[bind, function] bind a cast
by Alexander Gutenev 21 Feb '08

21 Feb '08

Hi Is there any easy way to bind an explicit type conversion ? For example, I want to supress compiler warning here with static_cast: #include <boost/bind.hpp> #include <boost/function.hpp> int main(void) { boost::function<long (void)> foo; boost::function<short (void)> bar; bar = foo; // compiler warning. bar = boost::bind<short>(foo); // the same warning //bar = boost::bind(static_cast<short>, foo); // does not compile return 0; } If not, I think it might be added. Casts are useful sometimes not only to avoid warning, but also to get code compiled.

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[Thread] Error compiling from svn trunk (tss.hpp)
by Luiz Marques 21 Feb '08

21 Feb '08

Hi, I'm trying to compile my code with boost.thread from SVN trunk (gcc 4.1.2, Fedora 7). I get the following error : /include/boost/thread/pthread/tss.hpp:55: error: invalid conversion from void* to MyThread* The code being compiled creates a thread_specific_ptr with a custom cleanup function, and is OK with boost 1.34 . Looking at the specified header, in line 55 there is a call to the custom cleanup_function: void operator()(void* data) { cleanup_function(data); } It seems like a static_cast<T*> is missing in the parameter. I changed it locally and the problem was solved. Can anyone confirm this problem ? Thanks, Luiz Marques

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Re: [Boost-users] [regex] Why pattern anchored at buffer end ($)alsomatch for (\x0c)FF, (\x0d)CR
by Chandan Nilange 21 Feb '08

21 Feb '08

I am restarting this old thread. My Question: How to modify Boost regex library, to match perl behavior, such that, I only get pattern matches after/before \n and ignore (\x0c)FF, (\x0d)CR for $ & ^ anchored patterns ? Regards, Chandan John Maddock wrote: >Chandan Nilange wrote: > > >>Hello John, >> >>I not very clear. >> >>So do you mean that - >> >>$ & ^ matching pattern after/before any (\x0c)FF, >>(\x0d)CR is right PCRE /m modifier behaviour. >> >> > >I believe so, but deciding what the right behaviour should be is not >necessarily easy: Perl has the luxury that it controls File IO as well as >regexes: in contrast Boost.Regex is designed to accept text from all kinds >of sources and platforms. Most applications will in any case regard an >isolated \r or \n as a line break, as well as \r\n. Likewise in what sense >does a form-feed *not* start a new line? :-) > >HTH, John. > >_______________________________________________ >Boost-users mailing list >Boost-users(a)lists.boost.org >http://lists.boost.org/mailman/listinfo.cgi/boost-users > > ____________________________________________________________________________________ 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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which toolset for VC8 on XP64
by Andreas Fabri 21 Feb '08

21 Feb '08

Hello, With the precompiled boost libs from boost-consulting I get linker errors error LNK2019: unresolved external symbol "private: void __cdecl boost::detail::tss::init(class boost::function1<void,void *,class std::allocator<class boost::function_base> > *)" (?init@tss@detail@boost@@AEAAXPEAV?$function1@XPEAXV?$allocator@Vfunction_base@boost@@@std@@@3@@Z) referenced in function "public: __cdecl boost::detail::tss::tss(class boost::function1<void,void *,class std::allocator<class boost::function_base> > *)" (??0tss@detail@boost@@QEAA@PEAV?$function1@XPEAXV?$allocator@Vfunction_base@boost@@@std@@@2@@Z) I started a shell such that Microsoft Visual Studio 8/VC/BIN/amd64/CL.EXE is the compiler on the $PATH I then run bjam --toolset=msvc" but the problem persists. Is there another toolset I have to choose? thanks in advance, andreas

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Link errors using VC++ 9.0, with Boost libs compiled with VC++ 8.0
by David Hartman 21 Feb '08

21 Feb '08

I'm compiling and linking using VC++ 9.0, and using Boost libraries built with VC++ 8.0. Unresolved external link errors are returned. Has anyone else had this problem? I'm going to build the Boost libraries using VC++ 9.0, for use with VC++ 9.0, but I was wondering if anyone else has tried to migrate to VC++ 9.0, and how they handled it. An example of the link error is below. 28>libboost_unit_test_framework-vc80-mt-gd.lib(xml_report_formatter.obj) : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall std::_Container_base::~_Container_base(void)" (__imp_??1_Container_base@std@@QAE@XZ) referenced in function "protected: void __thiscall std::vector<struct std::pair<char,char const *>,class std::allocator<struct std::pair<char,char const *> > >::_Tidy(void)" (?_Tidy@?$vector@U?$pair@DPBD@std@@V?$allocator@U?$pair@DPBD@std@@@2@@std@@IAEXXZ) David Hartman

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[program_options] Unicode problem
by Sergei Politov 21 Feb '08

21 Feb '08

The following example could not be compiled: ================================================================= #include <string> #include <boost/program_options.hpp> namespace po = boost::program_options; int main() { std::wstring test; po::options_description desc("Allowed options"); desc.add_options() ("test", po::wvalue<std::wstring>(&test)->default_value(L"value"), "description"); } ================================================================= It is due to wvalue::default_value tries to do lexical_cast<std::string>(std::wstring). Also I cannot change default_value to default_value("value") as soon as it accepts only something convertible to std::wstring. In other words it is impossible to specify default_value for wstring option.

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