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[Beginner] Setting up a function which generates normally distributed numbers
by Snorre Jakobsen 13 Oct '05

13 Oct '05

Hello I'm sorry if this is answered in the documentation, but I didn't find it. I want a function which returns a normally distributed number. #include <boost/random.hpp> #include <time.h> using namespace boost; double SampleNormal (double mean, double sigma) { mt19937 rng; // select random number generator rng.seed((unsigned int) time(0)); // seconds since 1970 // select desired probability distribution normal_distribution<double> norm_dist(mean, sigma); // bind random number generator to distribution, forming a function variate_generator<mt19937&, normal_distribution<double> > normal_sampler(rng, norm_dist); // sample from the distribution return normal_sampler(); } This (from http://surl.se/tvk) works very well, except if it's invoked (with same parameters) more often than once a second. If so, the generator gets equal seeds and returns equal values. How can I construct my program so the seeding happens only once? My experience with templates is limited, but I do have a grasp of the idea. Thanks for any hints. Snorre Jakobsen, Norway

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thread-safe iostreams - ideas for implementation ?
by marc 12 Oct '05

12 Oct '05

thread-safe iostreams - ideas for implementation ? I am currently experimenting with the boosth thread/mutex libraries, and did notice that the standard io streams are not thread safe. In the boost examples, this is handles by some global mutexes which are locked before writing to cout, cerr. I would like to have some classes which - behave exactly as cout, cerr and named file out streams - are thread safe mutex locked Are there any ideas on how to do this ?? I have the following possibilities in mind: 1) make a wrapper class around ostreams which have assigned a specific file or ostream as a member, make each input to operator<<() locked by a lock to a static mutex. advantage: not that hard to implement disadvantage: when outputting multiple things, like in mutex-cout << 'A' << 'B' << std::endl; another thread can come in between 'A' and 'B'. Not really thread safe, as I would like to have the entire line protected. 2) Make some trickery with manipulators and use the std:: stremas, something like cout << lock << 'A' << 'B' << std::endl << unlock ; advantage: pretty ok syntax (albeit one can forget to unlock!) disadvantage: I really have no idea how to implement in a niece and easy way .. 3) Make some trickery with out-put buffering something like having a class modeled like a stream_buff, which is large enough to hold what's written to the associated streams, and which does write to the cout or file streams in a mutex-locked fashion whenever it's manually flushed. ??? silly or possible ?? 4) finaly, a class having a boring print(std::string) function, which sets a lock on the static mutex advantage: easy-peasy disadvantage: C-print like, needs a new class type for each out-file, as a new static mutex has to be assigned to each out-file No nice C++ straming possible whatever I want to write needs to be converted into a std::string first. implementatio: can be templated by a string parameter which is the name of the file, or 'cout'/'cerr' Probably my ideas are not very bright, so I would appreciate some input from boost::thread users, which undoubtely have met the same problem before. Cheers, Marc -- Marc Cromme, cand. polyt, Ph.D Senior Developer, Project Manager Index Data Aps Købmagergade 43, 2 1150 Copenhagen K. Denmark tel: +45 3341 0100 fax: +45 3341 0101 http://www.indexdata.com INDEX DATA Means Business for Open Source and Open Standards

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[Review] TR1 library accepted
by Beman Dawes 12 Oct '05

12 Oct '05

John Maddock's TR1 library is accepted by Boost. Coincidentally, ISO has just announced that TR1 unanimously passed its final ballot, and so is now official. There were four reviews of John's submission, all urging acceptance. For most of the relatively few issues raised during review, John has already responded. Unless I missed it, however, John hasn't responded to Jonathan Wakely's review comments yet, anduld do so when he gets a chance. For example: It might be useful to list all the BOOST_HAS_TR1_XXX macros on the Configuration page, so you can glance at them all at once (most people will know what components each macro relates to.) Otherwise you have to read through a lot of text on the "TR1 By Subject" page to see what's available. Congratulations to John, and thanks to our reviewers! --Beman Dawes, Review Manager

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compiling fails on MacOS X
by Ákos Maróy 12 Oct '05

12 Oct '05

Hi, I'm trying to compile boost 1.33 on MacOS X, and I get a number of failures. I have: $ uname -a Darwin akos-maroys-mac-mini.local 8.2.0 Darwin Kernel Version 8.2.0: Fri Jun 24 17:46:54 PDT 2005; root:xnu-792.2.4.obj~3/RELEASE_PPC Power Macintosh powerpc $ gcc --version powerpc-apple-darwin8-gcc-4.0.0 (GCC) 4.0.0 (Apple Computer, Inc. build 5026) Copyright (C) 2005 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. I compiled bjam first (without problems), and then issues the following command (according to the documentation): ./tools/build/jam_src/bin.macosxppc/bjam -sTOOLS=darwin --prefix=/tmp/boost I get the following errors: darwin-Archive-action bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a ranlib: file: bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a(icu.o) has no symbols ranlib: file: bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a(regex_debug.o) has no symbols ranlib: file: bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a(w32_regex_traits.o) has no symbols ranlib: file: bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a(usinstances.o) has no symbols system-Ranlib bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a ranlib: file: bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a(icu.o) has no symbols ranlib: file: bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a(regex_debug.o) has no symbols ranlib: file: bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a(w32_regex_traits.o) has no symbols ranlib: file: bin/boost/libs/regex/build/libboost_regex.a/darwin/release/libboost_regex-1_33.a(usinstances.o) has no symbols darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_prg_exec_monitor.dylib/darwin/debug/shared-linkable-true/libboost_prg_exec_monitor-d-1_33.dylib ld: Undefined symbols: __Z8cpp_mainiPPc /usr/bin/libtool: internal link edit command failed ...failed darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_prg_exec_monitor.dylib/darwin/debug/shared-linkable-true/libboost_prg_exec_monitor-d-1_33.dylib... darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_prg_exec_monitor.dylib/darwin/release/shared-linkable-true/libboost_prg_exec_monitor-1_33.dylib ld: Undefined symbols: __Z8cpp_mainiPPc /usr/bin/libtool: internal link edit command failed ...failed darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_prg_exec_monitor.dylib/darwin/release/shared-linkable-true/libboost_prg_exec_monitor-1_33.dylib... darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_test_exec_monitor.dylib/darwin/debug/shared-linkable-true/libboost_test_exec_monitor-d-1_33.dylib ld: Undefined symbols: __Z9test_mainiPPc /usr/bin/libtool: internal link edit command failed ...failed darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_test_exec_monitor.dylib/darwin/debug/shared-linkable-true/libboost_test_exec_monitor-d-1_33.dylib... darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_test_exec_monitor.dylib/darwin/release/shared-linkable-true/libboost_test_exec_monitor-1_33.dylib ld: Undefined symbols: __Z9test_mainiPPc /usr/bin/libtool: internal link edit command failed ...failed darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_test_exec_monitor.dylib/darwin/release/shared-linkable-true/libboost_test_exec_monitor-1_33.dylib... darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_unit_test_framework.dylib/darwin/debug/shared-linkable-true/libboost_unit_test_framework-d-1_33.dylib ld: Undefined symbols: __Z20init_unit_test_suiteiPPc /usr/bin/libtool: internal link edit command failed ...failed darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_unit_test_framework.dylib/darwin/debug/shared-linkable-true/libboost_unit_test_framework-d-1_33.dylib... darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_unit_test_framework.dylib/darwin/release/shared-linkable-true/libboost_unit_test_framework-1_33.dylib ld: Undefined symbols: __Z20init_unit_test_suiteiPPc /usr/bin/libtool: internal link edit command failed

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Errors compiling greg_month.cpp
by D. R. Evans 12 Oct '05

12 Oct '05

I just upgraded to 1.33.0, and am getting a bunch of compilation errors with the current version of greg_month.cpp: The list of errors starts with: c:\boost\boost_1_33_0\boost\date_time\gregorian\formatters.hpp(34) : error C2977: 'date_formatter' : too many template arguments c:\boost\boost_1_33_0\boost\date_time\date_formatting_limited.hpp(114) : see declaration of 'date_formatter' c:\boost\boost_1_33_0\boost\date_time\gregorian\formatters.hpp(40) : see reference to function template instantiation 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl boost::gregorian::to_simpl e There are 31 errors in all. Using VC++ 6.0 on XP Service Pack 2. I would appreciate any gentle pointers as to what I might be doing wrong. Doc

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Short Mailing List Outage on Thursday 10/13
by Jeff Garland 12 Oct '05

12 Oct '05

FYI -- I believe this will impact Boost-Users as well. ------------------ I am sorry for this short notice but I need to reboot milliways to upgrade its firmware. It will be down for about 1 hour Thursday morning (10/13). - 6:00am-7:00am Pacific US time - 7:00am-8:00am Mountain US time - 8:00am-9:00am Central US time - 9:00am-10:00am Eastern US time - 1:00pm-2:00pm GMT Specifically, the following services provided by the OSL will be unavailable during this timeframe: - All e-mail services - Incoming mail (including all mailman list hosting) - Outgoing mail (including all mailman list hosting) - IMAP/SSL - All web hosting - lists.boost.org - ...and all others hosted by the OSL

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typeof
by Karl Meerbergen 12 Oct '05

12 Oct '05

Hello, Looking at the regression test results, it seems that some typeof tests do not compile on IBM. Did somebody have a look at this? Is this a known problem? Thanks, Karl

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Crash when assign value to regex object
by Aaron 12 Oct '05

12 Oct '05

The code snippet: struct Grepper { int nPriority; boost::regex re; pONGREPFOUNDCALLBACK pOnGrepFoundSymbols; friend bool operator< (const Grepper& g1, const Grepper& g2) { return g1.nPriority > g2.nPriority; } }; if (...){ Grepper gp; if (QueryGreppers(gp)) g_vecGreppers.push_back(gp); } bool QueryGreppers(Grepper& gp) { gp.nPriority = 1; gp.re ="\\s*#define\\s+([^\\s]+)\\s+([^/\\r\\n]+)([^\\r\\n]*)"; gp.pOnGrepFoundSymbols = OnGrepSingleLineSymbols; return true; } Program fails at gp.re = ... The call stack is: _CrtIsValidHeapPointer(const void * 0x012e61f8) line 1606 _free_dbg_lk(void * 0x012e61f8, int 1) line 1011 + 9 bytes _free_dbg(void * 0x012e61f8, int 1) line 970 + 13 bytes free(void * 0x012e61f8) line 926 + 11 bytes operator delete(void * 0x012e61f8) line 7 + 9 bytes boost::detail::simple_alloc::deallocate(void * 0x012e61f8, unsigned int 1024) line 213 + 9 bytes boost::detail::allocator_adapter<unsigned char,boost::detail::simple_alloc>::deallocate(unsigned char * 0x012e61f8, unsigned int 1024) line 258 boost::re_detail::raw_storage<boost::detail::allocator_adapter<char,boost::detail::simple_alloc> >::resize(boost::re_detail::raw_storage<boost::detail::allocator_adapter<char,boost::detail::simple_alloc> > * const 0x0012eff0, unsigned int 1120) line 223 boost::re_detail::raw_storage<boost::detail::allocator_adapter<char,boost::detail::simple_alloc> >::extend(boost::re_detail::raw_storage<boost::detail::allocator_adapter<char,boost::detail::simple_alloc> > * const 0x0012eff0, unsigned int 268) line 131 + 27 bytes boost::reg_expression<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> >::compile_set_aux(boost::reg_expression<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> > * const 0x0012efe8, ...) line 1145 + 17 bytes boost::reg_expression<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> >::compile_set_simple(boost::reg_expression<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> > * const 0x0012efe8, boost::re_detail::re_syntax_base * 0x012e6534, unsigned long 8, unsigned char 0) line 737 + 48 bytes boost::reg_expression<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> >::set_expression(boost::reg_expression<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> > * const 0x0012efe8, const char * 0x0846601c `string', const char * 0x08466049, unsigned int 34055) line 1651 + 20 bytes boost::reg_expression<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> >::set_expression(boost::reg_expression<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> > * const 0x0012efe8, const char * 0x0846601c `string', unsigned int 34055) line 238 + 59 bytes boost::reg_expression<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> >::assign(const char * 0x0846601c `string', unsigned int 33031) line 89 + 20 bytes boost::basic_regex<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> >::operator=(boost::basic_regex<char,boost::regex_traits<char>,boost::detail::allocator_adapter<char,boost::detail::simple_alloc> > * const 0x0012efe8, const char * 0x0846601c `string') line 356 QueryGreppers(Grepper & {...}) line 35 + 17 bytes What's wrong with it?

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[Parameter library]
by Sohail Somani 11 Oct '05

11 Oct '05

Is the prescribed method for the parameter library thread safe? // appears to modify global variables "graph", etc core::depth_first_search(( graph = 'G', visitor = 2, root_vertex = 3.5, index_map = "hello, world", color_map = false)); Thanks

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[iostreams] Problems using filtering_stream and code_converter
by Niklas Wiberg 11 Oct '05

11 Oct '05

Hi, I'm using boost 1.33.0 on windows (VC++6). I would like to use a code_converter to convert internal std::wstring's (which I understand are ucs2 in windows/vstudio, but that shouldn't matter here I guess) to utf-8 when saving to file. Here is the failing code: <code> void main() { typedef boost::iostreams::code_converter<boost::iostreams::file_sink, WideCharToUtf8Cvt> my_sink; std::wstring teststr(L"Blah blah."); boost::iostreams::filtering_wostream out; boost::iostreams::file_sink myFile("out.txt"); out.push(my_sink(myFile)); out << teststr; } </code> WideCharToUtf8Cvt is my own codecvt implementation. The problem is that I get a crash as the stream is being destroyed. The call stack is too deep to include here, but one of the last things are: policy_type& dev() { return **dev_; } in boost.iostreams.detail.code_converter_impl which calls boost::iostreams::detail::optional<boost::iostreams::detail::concept_adapter<boost::iostreams::basic_file_sink<char> > >::operator*() operator*() asserts on initialized_ which is false in this case. I've tried both with vc++6 sp5 and vc++ 7.1 with the same results. Also, there is no difference if I use this typedef for my_sink: typedef boost::iostreams::code_converter<boost::iostreams::file_sink> my_sink; so I don't think my codecvt implementation is to blame... The file out.txt actually gets filled with the expected data. Am I going about this the completely wrong way or am I just missing some important detail? Any help would be greatly appreciated, Niklas Wiberg

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