September 2005 - Boost-users

[lambda] Variable assignment from lambda expression
by Alexander Borghgraef 30 Sep '05

30 Sep '05

Hi all, I have been trying out boost::lambda for the first time, and I did encounter something which I can't seem to solve. Simplified, what I'd like to do amounts to this: list<int> intlist; // fill up list someway int n; for_each( intlist.begin(), intlist.end(), n = _1 ); Obviously, this fails because it implies a cast from placeholder to int, which isn't defined. Is there some way to do this using lambda? -- Alex Borghgraef

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[iostreams] Linker error
by Klaus Nowikow 30 Sep '05

30 Sep '05

Hi, with the following test program: <code> #include <boost/iostreams/filter/bzip2.hpp> int main(int argc, char* argv[]) { return 0; } </code> I get the linker error (MSVC 7.1): LINK : fatal error LNK1104: cannot open file 'libboost_bzip2-vc71-mt-1_33.lib' A similar error occurs with "zlib.hpp" instead of "bzip2.hpp": LINK : fatal error LNK1104: cannot open file 'libboost_zlib-vc71-mt-1_33.lib' I did not find this lib files in my Boost library directory, so I might have missed something when I built Boost. This is what I did: - Got the sources for the bzip2 and the zlib libraries - Built the libs - Built Boost with this command line: bjam "-sTOOLS=vc-7_1" "-sNO_COMPRESSION=0" "-sNO_ZLIB=0" "-sZLIB_LIBPATH=c:/dev/Libraries/zlib/lib" "-sZLIB_INCLUDE=c:/dev/Libraries/zlib/include/zlib" "-sNO_BZIP2=0" "-sBZIP2_LIBPATH=c:/dev/Libraries/bzip2/lib" "-sBZIP2_INCLUDE=c:/dev/Libraries/bzip2/include/bzip2" (without the line breaks of course) The names of the bzip2 / zlib libraries are libbz2.lib and zdll.lib, resp., and the paths are correct. I did not get any error messages when building Boost, and I also did not get the "Building Boost.Iostream with .. support disabled..." message. Is there anything that I missed from the docs? Best regards, Klaus

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Which boost libraries need libs?
by Richard Kaiser 29 Sep '05

29 Sep '05

Can anybody tell me, which of the Boost libraries need libs (usually created with bjam)? As far as I can see, for most of the Boost libraries source code #includes are sufficient. For them, installation step 1 from the "Getting Started"-page is sufficient. Or do I get something wrong? Richard

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the strange warnings in using of boost::format
by Alan Huang 29 Sep '05

29 Sep '05

hi, here is the code fragment in my win32 project: namespace gtl { typedef unsigned int dword; }; void myFun( const char * _szText ){} int i = 10; myFun( boost::str( boost::format( " Page %2d" ) %i ).c_str() ); but there is so many more warinings as below: LobbyRoomListWnd.cpp d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(100) : warning C4244: '+=' : conversion from '__w64 int' to 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type', possible loss of data with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(267) : while compiling class-template member function 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::pos_type boost::io::basic_altstringbuf<Ch,Tr,Alloc>::seekoff (boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type,std::_Iosb<_Dummy>::seekdir,std::_Iosb<_Dummy>::openmode)' with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char>, _Dummy=int ] d:\working\alan_gamma\publiclibrary\boost\boost\format\format_class.hpp(136) : see reference to class template instantiation 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>' being compiled with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\richonlineclient\roclient\game\lobby\lobbyroomlistwnd.cpp(427) : see reference to class template instantiation 'boost::basic_format<Ch>' being compiled with [ Ch=char ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(102) : warning C4244: '+=' : conversion from '__w64 int' to 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type', possible loss of data with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(110) : warning C4244: 'argument' : conversion from '__w64 int' to 'int', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(118) : warning C4244: '+=' : conversion from '__w64 int' to 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type', possible loss of data with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(120) : warning C4244: '+=' : conversion from '__w64 int' to 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::off_type', possible loss of data with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(151) : warning C4244: 'argument' : conversion from '__w64 int' to 'int', possible loss of data c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(267) : while compiling class-template member function 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::pos_type boost::io::basic_altstringbuf<Ch,Tr,Alloc>::seekpos (boost::io::basic_altstringbuf<Ch,Tr,Alloc>::pos_type,std::_Iosb<_Dummy>::openmode)' with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char>, _Dummy=int ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(160) : warning C4244: 'argument' : conversion from '__w64 long' to 'int', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(265) : warning C4244: 'initializing' : conversion from '__w64 int' to 'int', possible loss of data c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(267) : while compiling class-template member function 'boost::io::basic_altstringbuf<Ch,Tr,Alloc>::int_type boost::io::basic_altstringbuf<Ch,Tr,Alloc>::overflow (boost::io::basic_altstringbuf<Ch,Tr,Alloc>::int_type)' with [ Ch=char, Tr=std::char_traits<char>, Alloc=std::allocator<char> ] d:\working\alan_gamma\publiclibrary\boost\boost\format\alt_sstream_impl.hpp(266) : warning C4244: 'initializing' : conversion from '__w64 int' to 'int', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\format\format_implementation.hpp(193) : warning C4267: 'initializing' : conversion from 'size_t' to 'std::streamsize', possible loss of data c:\program files\microsoft visual studio .net 2003\vc7\include\ios(119) : while compiling class-template member function 'boost::basic_format<Ch>::string_type boost::basic_format<Ch>::str(void) const' with [ Ch=char ] c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(267) : while compiling class-template member function 'boost::basic_format<Ch>::basic_format(const Ch *)' with [ Ch=char ] d:\working\alan_gamma\publiclibrary\boost\boost\format\format_implementation.hpp(206) : warning C4267: 'initializing' : conversion from 'size_t' to 'std::streamsize', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\optional\optional.hpp(102) : while compiling class-template member function 'boost::basic_format<Ch>::size_type boost::basic_format<Ch>::size(void) const' with [ Ch=char ] c:\program files\microsoft visual studio .net 2003\vc7\include\ios(119) : while compiling class-template member function 'boost::basic_format<Ch> &boost::basic_format<Ch>::parse(const boost::basic_format<Ch>::string_type &)' with [ Ch=char ] d:\working\alan_gamma\publiclibrary\boost\boost\format\format_implementation.hpp(210) : warning C4267: '+=' : conversion from 'size_t' to 'std::streamsize', possible loss of data d:\working\alan_gamma\publiclibrary\boost\boost\format\format_implementation.hpp(213) : warning C4267: '+=' : conversion from 'size_t' to 'std::streamsize', possible loss of data RichOnline.cpp c:\program files\microsoft visual studio .net 2003\vc7\include\xutility(1136) : warning C4267: '=' : conversion from 'size_t' to 'std::allocator<_Ty>::value_type', possible loss of data with [ _Ty=gtl::dword ] c:\program files\microsoft visual studio .net 2003\vc7\include\vector(862) : see reference to function template instantiation 'void std::fill<std::vector<_Ty>::_Tptr,_Ty>(_FwdIt,_FwdIt,const _Ty &)' being compiled with [ _Ty=size_t, _FwdIt=std::vector<size_t>::_Tptr ] c:\program files\microsoft visual studio .net 2003\vc7\include\vector(809) : while compiling class-template member function 'void std::vector<_Ty>::_Insert_n(std::vector<_Ty>::iterator,std::vector<_Ty>::size_type,const _Ty &)' with [ _Ty=size_t ] d:\working\alan_gamma\publiclibrary\boost\boost\regex\v4\cregex.hpp(229) : see reference to class template instantiation 'std::vector<_Ty>' being compiled with [ _Ty=size_t ] c:\program files\microsoft visual studio .net 2003\vc7\include\xutility(1161) : warning C4267: '=' : conversion from 'size_t' to 'std::allocator<_Ty>::value_type', possible loss of data with [ _Ty=gtl::dword ] c:\program files\microsoft visual studio .net 2003\vc7\include\memory(237) : see reference to function template instantiation 'void std::fill_n<_Ty*,_Diff,_Tval>(_OutIt,_Diff,const _Ty &)' being compiled with [ _Ty=std::allocator<gtl::dword>::value_type, _Diff=std::vector<size_t>::size_type, _Tval=size_t, _OutIt=std::allocator<gtl::dword>::value_type * ] c:\program files\microsoft visual studio .net 2003\vc7\include\memory(257) : see reference to function template instantiation 'void std::_Uninit_fill_n<std::allocator<_Ty>::value_type,_Diff,_Tval>(_Ty *,_Diff,const _Tval &,std::allocator<_Ty> &,std::_Scalar_ptr_iterator_tag)' being compiled with [ _Ty=gtl::dword, _Diff=std::vector<size_t>::size_type, _Tval=size_t ] c:\program files\microsoft visual studio .net 2003\vc7\include\vector(878) : see reference to function template instantiation 'void std::_Uninitialized_fill_n<std::vector<_Ty>::pointer,std::vector<_Ty>::size_type,_Ty,std::_Vector_val<_Ty,_Alloc>::_Alty>(_FwdIt,_Diff,const _Tval &,_Alloc &)' being compiled with [ _Ty=size_t, _Alloc=std::allocator<gtl::dword>, _FwdIt=std::vector<size_t>::pointer, _Diff=std::vector<size_t>::size_type, _Tval=size_t ] c:\program files\microsoft visual studio .net 2003\vc7\include\vector(877) : while compiling class-template member function 'std::vector<_Ty>::pointer std::vector<_Ty>::_Ufill(std::vector<_Ty>::pointer,std::vector<_Ty>::size_type,const _Ty &)' with [ _Ty=size_t ] thanks very much for any reply. -- Yours Sincerely, Alan Huang

2 1

[lambda]Predicate construction
by Anakreon 29 Sep '05

29 Sep '05

I tried to create a predicate based on lambda expressions. The attempt failed with compiler errors so finally I created a struct to do the job. The problem is: I have a vector with pointers of objects of class Event. vector<Event*> events and want to call find_if on the vector. The struct which does this is: struct event_locator: public unary_function<bool, Event*> { int tId; event_locator(const int tid) : tId(tid) {} const bool operator() (Event* e) { return e->hasTransaction() && e->getTransaction().getId() == tId; } }; The main problem in translating the code in the struct into lambda expressions is that I don't know how to call a method from the placeholder like:_1->hasTransaction(). I tried _1->* &Event::hasTransaction without success.

3 5

MSVC v6 build fails in file boost\detail\shared_count.hpp
by David Balazic 29 Sep '05

29 Sep '05

Hi! I had to change line 216 in file boost\detail\shared_count.hpp from : void * get_deleter(std::type_info const & ti) const { to void * get_deleter(type_info const & ti) const { to get it built. (I am using boost in a prokejet. The build of my project fails in the above file ). I also had to make the same change in files boost\detail\sp_counted_base_w32.hpp and boost\detail\sp_counted_impl.hpp I have Visual Studio c++ 6.0. Is this a known problem ? Will it be pathced ? Regards, David --------------------------------------------------------------------- http://noepatents.eu.org/ Innovation, not litigation ! --- David Balazic mailto:david.balazic@hermes.si HERMES Softlab http://www.hermes-softlab.com Zagrebska cesta 104 Phone: +386 2 450 8851 SI-2000 Maribor Slovenija --------------------------------------------------------------------- "Be excellent to each other." - Bill S. Preston, Esq. & "Ted" Theodore Logan ---------------------------------------------------------------------

2 1

Spirit and CTTL
by Aaron Griffin 29 Sep '05

29 Sep '05

Ok, I didn't go to school for computer programming, so I never had experience with a "Compilers" class or anything related to lexing/parsing. But now I'm getting interested in it and have begun looking at some things. Spirit seems good, but it seems very weighty to work with. I was wondering if anyone has experiences with Spirit *and* CTTL and would be able to list for me some of the pros and cons of each. Spirit is, of course, a boost library and would be easier to find help and things of that nature, but CTTL seems to be a tad more lightweight (I'm not really sure). Thanks for any and all replies.

5 10

BOOST_CHECK_CLOSE with integral types
by Will Bryant 29 Sep '05

29 Sep '05

Hi all, Is BOOST_CHECK_CLOSE supposed to work with integral types? I find that if I try: long var1 = 1001; BOOST_CHECK_CLOSE(var1, 2000L, 10L); under both MSVC 2005 and GCC 3.4, it'll pass, which is wrong as far as I can see - whereas: double var2 = 1001.0; BOOST_CHECK_CLOSE(var2, 2000.0, 10.0); fails as it should. Why is this? int has the same problem. Cheers, Will -- Will Bryant http://carcino.gen.nz/ will(a)core-dev.co.nz +64 21 655 443

2 5

Using indirect_iterators for input
by Alexander Borghgraef 29 Sep '05

29 Sep '05

Hi all, I've been experimenting with indirect_iterator, which seems to be a very useful concept. However, I'm having some trouble getting it to work in the case where I want to fill a container with pointers to values, not just getting at the data. For example, this compiles but segfaults: std::vector < int * > v( 10 ); std::fill( boost::make_indirect_iterator( v.begin() ), boost::make_indirect_iterator( v.end() ), 1.0 ); Another case: std::vector< boost::shared_ptr<double> > v(10); std::vector< boost::shared_ptr<double> > w(10); // v gets filled somehow std::copy( boost::make_indirect_iterator( v.begin() ), boost::make_indirect_iterator( v.end() ), boost::make_indirect_iterator( w.begin() ) ); Why isn't this working? Also, some way to get it to work as a back_insert_iterator would be interesting, does this exist (aside from writing your own)? If not, are there any plans to incorporate it in future versions? -- Alex Borghgraef -- Alex Borghgraef

2 4

[serialization] Non intrusive splitting of serialize
by Marco Segurini 28 Sep '05

28 Sep '05

Hi, I like to know if is it possible to split the non intrusive 'serialize' to 'load/save/BOOST_SERIALIZATION_SPLIT_...(<class name>)' thanks. Marco.

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