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[multi_index][ann][rfc] Preview of Boost.MultiIndex 1.34 release
by Joaquín Mª López Muñoz 18 Jan '06

18 Jan '06

It is a pleasure for me to announce the availability of a preview version of Boost.MultiIndex as planned for shipping with Boost 1.34, downloadable at the Vault: http://www.boost-consulting.com/vault/index.php?&direction=0&order=&directo… (file multi_index.zip) This version includes several important new features: * New random access indices, which behave like sequenced indices with the added benefit of random access semantics. * Rearrange facilities in sequenced and random access indices, allowing for interoperability with external mutating algorithms. This is IMHO an important feature that can open up new usage scenarios for Boost.MultiIndex. * Several optimizations, of which the most important one relates to ordered indices headers, which are now 4 bytes shorter (on 32 bit systems): this optimization also leads to better performance for large numbers of elements. All in all, the upgrade is very extensive, so I'd appreciate if you test if for backwards compatibility even if you don't plan to use the new features. Additionally, I'd greatly welcome receiving any kind of feedback on the new stuff, the docs (which has been restructured and expanded) and whatever aspect you might think can be improved. I plan to commit this new version to the CVS in a couple of weeks or so, so if you have any comments please bring them here now! Thanks very much for your interest in the library, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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<smart_ptr>: A newbie question (about BOOST_SP_USE_QUICK_ALLOCATOR)
by Svaley Streasm 18 Jan '06

18 Jan '06

Hi, I understand that shared_ptr uses the 'quick_allocator' when I compile the library with BOOST_SP_USE_QUICK_ALLOCATOR. But this means that I get the 'quick_allocator' working for every type that I use with shared_ptr, and this bothers me because this seems as a waste of memory for instances of classes that are not frequently used. Besides, the 'quick_allocator' unlike Scott Meyers suggestion (use a pool that can be destroyed) doesn't frees its free blocks which means that, shared_ptr of types that are used only in initialization stage will occupy memory which can not be recycled. Am I missing something? Thank you, Svaley --------------------------------- Yahoo! Photos Ring in the New Year with Photo Calendars. Add photos, events, holidays, whatever.

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[posix_time] truncation warning from VC71
by Dale Wilson 18 Jan '06

18 Jan '06

Hi, (possible duplicate, but I think the original was rejected 'cause of a mail alias. If not, please forgive the noise.) I'm using boost 1.32 posix_time in some code that is intended to be portable (MS VC7.1 / Solaris gcc 3.3.1 / RHLinux gcc 3.3.1). When I build with VC 7.1.3088 on Windows XP Pro SP2 get warnings about integer trunction (see below). I can duplicate it by compiling a cpp file containing a single line: #include "boost/date_time/posix_time/posix_time.hpp" and I can work around it by: #ifdef _MSC_VER #pragma warning(push) #pragma warning(disable:4244) // boost/posix_time has truncation warnings #endif // _MSC_VER #include "boost/date_time/posix_time/posix_time.hpp" //include all types plus i/o #ifdef _MSC_VER #pragma warning(pop) #endif // _MSC_VER but this might hide real problems (or this might *BE* a real problem -- I haven't really looked into the difference between a boost::date_time::counted_time_rep<config>::int_type. and a boost::date_time::gregorian_calendar_base<ymd_type_,date_int_type_>::date_int_type Suggestions? Dale The warnings: c:\Boost\include\boost-1_32\boost\date_time\time_system_counted.hpp(57) : warning C4244: 'initializing' : conversion from 'boost::date_time::counted_time_rep<config>::int_type' to 'boost::date_time::gregorian_calendar_base<ymd_type_,date_int_type_>::date_int_type', possible loss of data with [ config=boost::posix_time::millisec_posix_time_system_config ] and [ ymd_type_=boost::gregorian::greg_year_month_day, date_int_type_=boost::date_time::int_adapter<unsigned long>::int_type ] c:\Boost\include\boost-1_32\boost\date_time\time_system_counted.hpp(52) : while compiling class-template member function 'boost::date_time::counted_time_rep<config>::date_type boost::date_time::counted_time_rep<config>::date(void) const' with [ config=boost::posix_time::millisec_posix_time_system_config ] c:\Boost\include\boost-1_32\boost\date_time\time_system_counted.hpp(111) : see reference to class template instantiation 'boost::date_time::counted_time_rep<config>' being compiled with [ config=boost::posix_time::millisec_posix_time_system_config ] c:\Boost\include\boost-1_32\boost\date_time\time.hpp(52) : see reference to class template instantiation 'boost::date_time::counted_time_system<time_rep>' being compiled with [ time_rep=boost::posix_time::int64_time_rep ] c:\Boost\include\boost-1_32\boost\date_time\posix_time\ptime.hpp(32) : see reference to class template instantiation 'boost::date_time::base_time<T,time_system>' being compiled with [ T=boost::posix_time::ptime, time_system=boost::posix_time::posix_time_system ] c:\Boost\include\boost-1_32\boost\date_time\date_parsing.hpp(211) : warning C4244: 'argument' : conversion from 'std::allocator<_Ty>::value_type' to 'char', possible loss of data with [ _Ty=wchar_t ] c:\Boost\include\boost-1_32\boost\date_time\date_parsing.hpp(253) : see reference to function template instantiation 'date_type boost::date_time::from_stream_type<date_type,std::basic_string<_Elem,_Traits,_Ax>::iterator>(iterator_type &,iterator_type &,wchar_t)' being compiled with [ date_type=boost::gregorian::date, _Elem=wchar_t, _Traits=std::char_traits<wchar_t>, _Ax=std::allocator<wchar_t>, iterator_type=std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>::iterator ] c:\Boost\include\boost-1_32\boost\date_time\gregorian\parsers.hpp(78) : see reference to function template instantiation 'boost::date_time::period<point_rep,duration_rep> boost::date_time::from_simple_string_type<boost::gregorian::date,wchar_t>(const std::basic_string<_Elem,_Traits,_Ax> &)' being compiled with [ point_rep=boost::gregorian::date, duration_rep=boost::gregorian::date_duration, _Elem=wchar_t, _Traits=std::char_traits<wchar_t>, _Ax=std::allocator<wchar_t> ] -- ----------------------------------------------------- Dale Wilson, Senior Software Engineer Object Computing, Inc. (OCI) http://www.ociweb.com/ http://www.theaceorb.com/ ----------------------------------------------------

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Boost Math Library
by yinglcs2＠yahoo.com 17 Jan '06

17 Jan '06

Hi, Does Boost Math Library support Statistic Calculation? (e.g. median, std deviation, etc)? >From here, it does not appear Boost Math library calculate has statistic algorithm. If not, can someone please recommend some c/c++ library which does statistics? Thank you. http://www.boost.org/libs/libraries.htm#Algorithms Math and numerics * math - Several contributions in the domain of mathematics, from various authors. * numeric/conversion - Optimized Policy-based Numeric Conversions, from Fernando Cacciola. * integer - Headers to ease dealing with integral types. * interval - Extends the usual arithmetic functions to mathematical intervals, from Guillaume Melquiond, Hervé Brönnimann and Sylvain Pion. * math/common_factor - Greatest common divisor and least common multiple, from Daryle Walker. * math/octonion - Octonions, from Hubert Holin. * math/quaternion - Quaternions, from Hubert Holin. * math/special_functions - Mathematical special functions such as atanh, sinc, and sinhc, from Hubert Holin. * multi_array - Multidimensional containers and adaptors for arrays of contiguous data, from Ron Garcia. * operators - Templates ease arithmetic classes and iterators, from Dave Abrahams and Jeremy Siek. * random - A complete system for random number generation, from Jens Maurer. * rational - A rational number class, from Paul Moore. * uBLAS - Basic linear algebra for dense, packed and sparse matrices, from Joerg Walter and Mathias Koch. __________________________________________ Yahoo! DSL Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com

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Serialization of static member variables?
by Joseph Turian 17 Jan '06

17 Jan '06

Hi, If see from the serialization documentation that if I serialize a pointer more than once, only one instance will appear in the archive. However, what about static member variables? Will they only be serialized once, even if I serialize multiple objects of the class type? e.g. class foo { private: int i; static int j; friend class boost::serialization::access; template<class Archive> void serialize(Archive& ar, const unsigned int version) { ar & i; ar & j; // Will j be serialized multiple times, i.e. once per foo instance? } }; Thanks, Joseph -- http://www.cs.nyu.edu/~turian/

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[serialization] default constructor problem
by Andreas Sæbjørnsen 17 Jan '06

17 Jan '06

Hi, I am currently experimenting with writing a compiler tool which generates the code necessary for using boost::serialization. While working on this I found that I am unable to serialize a variable declaration which is a reference to a class constructed with the default constructor '()'( ex. class foo var(); ). I have tried to find an explanation for this in the examples, documentation and through searching the web without success. Using pointers it works fine with the default constructor and I do not see why it should be any different for references (as references in essence are pointers). Is it possible to serialize a class constructed using the default constructor using boost::serialization, and if so how? Example: #include <fstream> // include headers that implement a archive in simple text format #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> class gps_set { friend class boost::serialization::access; public: int x; gps_set::gps_set(){ x = 2;}; virtual gps_set::~gps_set(){}; gps_set::gps_set(int i) : x(1) {}; private: template<typename Archive> void serialize(Archive& ar, const unsigned int version){ ar& x; }// End method: X::serialization }; int main() { // save the schedule std::ofstream ofs("filename"); // create class instance //Compile time error if s1() is used. No error if s1(1) is used. const gps_set s1(); // save data to archive { boost::archive::text_oarchive oa(ofs); // write class instance to archive oa << s1; // archive and stream closed when destructors are called } }; Thanks, Andreas Saebjoernsen

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[mpl] inherit_linearly
by David Greene 17 Jan '06

17 Jan '06

I'm trying something new using mpl's inherit_linearly but I can't figure out how to do what I want to do. The idea, simply: template<typename Policies> class Test : public inherit_linearly<Policies, inherit<_1, _2> >::type { public: void do_something(void) { for each Base in Policies Base::do_something(); rof } }; Is there a straightforward way to do this or am I thinking about this in the wrong way? -Dave

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Why don't smart pointers have the same semantics as plain pointers?
by Pierre THIERRY 17 Jan '06

17 Jan '06

I use more and more BOOST smart pointers instead of plain pointers in my C++ code, and it is incredible how it saves time and prevent bugs! But I was wondering why one couldn't just change the type of a pointer a keep all code as it is, instead of having to change affectation to reset(), for example. E.g., the following code: Foo* ptr_foo; ptr_foo = new Foo; Has now to be changed to: shared_ptr<Foo> ptr_foo; ptr_foo.reset(new Foo); But I'd like it to be: shared_ptr<Foo> ptr_foo; ptr_foo = new Foo; Is there a problem to have shared_ptr<T>::operator=(T*)? Curiously, Nowhere man -- nowhere.man(a)levallois.eu.org OpenPGP 0xD9D50D8A

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boost::spirit block of C++ code
by elviin 17 Jan '06

17 Jan '06

I created this parser and it is working for me except the detail: //------------------ //the body of the block cpp_code_block_text = *(anychar_p-ch_p('{')-ch_p('}')); //the code begins with '{' cpp_code_block_begin_p = ch_p('{'); //the code ends with '}' cpp_code_block_end_p = ch_p('}'); //parser: cpp_code_block_p = cpp_code_block_begin_p >> repeat_p (0, 100)[(cpp_code_block_p|cpp_code_block_text)] >> cpp_code_block_end_p; ---------------------- Here is the text I'm using for tests: {asas {bbbbbb bbb b b { asa}bb bbb b bb } as {aaaa} {aaaacc} asasa {} aaa } And the problem is in repeat_p (0, 100). I'd like to use * instead but it does not work for me because the parser runs forever. 100 means the number of blocks cpp_code_block_p or cpp_code_block_text. Where is the problem? Thank you very much for reply.

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Boost has a function to const-qualify?
by MB 16 Jan '06

16 Jan '06

Hi, Does boost has anything like : template< class T > inline const T& const_(const T& x) { return x; } I guess that boost::cref is different... Regards, MB p-stade.sourceforge.net

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