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[Interprocess]
by Daniel Neuberger 24 Jan '11

24 Jan '11

Hi Ion (and everyone else), I looked through the recent commits and it looks like support for XSI shared memory has been added (https:// svn.boost.org/trac/boost/changeset/67451) Does this mean XSI is ready to use now? Do you think these changes will make it into the upcoming 1.46 release? Alternatively, do you think applying the above changeset to Boost 1.43 be sufficient to be able to use XSI shared memory? Thanks again, - Daniel P.S. Sorry if anyone got another similar message to this from me; I sent one in response to another message but think the thread was already too old.

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Random: How to get a different seed?
by Zoltán Lengyel 24 Jan '11

24 Jan '11

Hello, I am trying to make a simple program that can generate random integers in range, using boost::uniform_int. http://www.boost.org/doc/libs/1_45_0/doc/html/boost_random/tutorial.html#bo… This tutorial tells: "We use mt19937<http://www.boost.org/doc/libs/1_45_0/doc/html/boost/mt19937.html>with the default seed as a source of randomness. The numbers produced will be the same every time the program is run. One common method to change this is to seed with the current time (std::time(0) defined in ctime)." I have trouble getting this common method compile and work. Here's a tiny program that works, with the same seed at every run (like what the tutorial does), I have commented out my desperate tries to make the seed change. #include "uniform_int.hpp" #include "boost/random/variate_generator.hpp" #include "boost/random/mersenne_twister.hpp" #include <time.h> #include <iostream> using namespace std; using namespace boost; mt19937 gen; // time_t gen = time(0); int roll_die() { uniform_int<> dist(1, 6); variate_generator<mt19937&, uniform_int<> > die(gen, dist); //boost::variate_generator<time_t, boost::uniform_int<> > die(gen, dist); return die(); } int main() { for (int i = 0; i < 5; i++) cout << roll_die() << endl; return 0; } So, I would be glad, if someone could fix this for me, to have a different seed (depending on system time) at each start. Thanks!

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[Preprocessor] Relative Addresses in BOOST_PP_FILENAME_1
by Hossein Haeri 24 Jan '11

24 Jan '11

Dear all, I am trying to use BOOST_PP_FILENAME_1 for a header file in my current directory. Unless I hardcode the full address, GCC 4.5.1 (MinGW32, WinXP, SP3) says it can't find the same file in which I am using BOOST_PP_FILENAME_1! Is there any way I can go for relative file names? I have already checked the following -- neither works for the same reasons: #define BOOST_PP_FILENAME_1 "./Header.hpp" //1 #define BOOST_PP_FILENAME_1 ".\Header.hpp" //2 #define BOOST_PP_FILENAME_1 "Header.hpp" //3 TIA, --Hossein

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[statechart] (custom) state queries for asynchronous state machine
by Loek Cleophas 24 Jan '11

24 Jan '11

Hi, I'm trying to figure out how to perform (custom) state queries on statechart's asynchronous state machines. The tutorial at http://www.boost.org/doc/libs/1_44_0/libs/statechart/doc/tutorial.html#Stat… how to do this for synchronous state machines - using state_iterator and the state machine's state_begin() and state_end() member functions. However, for the asynchronous case, access to the state machine is via a scheduler only - and I don't see how to get the information from there nor is there any documentation on that in the tutorial. Any hints on how to do this? Regards, Loek

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boost::trim throwing std::bad_cast exeption with custom basic_string
by Arash Abghari 24 Jan '11

24 Jan '11

Hi, I have a custom basic_string as follows: typedef basic_string<unsigned int> ustring; so if I pass an instance of ustring to boost:trim it throws an std::bad_cast exception. ustring str; boost::trim(str); The exception comes from here: include/boost/algorithm/string/detail/classification.hpp:45 return std::use_facet< std::ctype<CharT> >(m_Locale).is( m_Type, Ch ); It does not matter what character type I use for basic_string, It throws the exception for anything but char and wchar_t. Document mentions "A string is not restricted to std::basic_string and character does not have to be char or wchar_t, although these are most common candidates", So I assume, It must work with unsigned int or other types. Here is the system spec: boost: 1.40 gcc: 4.3.4 OS: Debian Lenny 64bit Thanks

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Re: [Boost-users] [Fusion] Building parameter list for fusion::invoke
by Vivek 24 Jan '11

24 Jan '11

> > 2011/1/22 Vivek <vivek_at_[hidden]> > Or alternatively, is there a direct way to initialize a fusion vector? IIUC, its ctor just do the job, not? The problem is I don't know the arity or parameter types of the function being called. I just have a source of data (which can be simplified to TYPE data = data_source<TYPE>().pop();) and arbitrary functions being passed in. One alternative is to code-generate template specializations for a bunch of arity and use the constructor like you suggested. But I feel the "arity code generation" thing has been done so many times and so much better in boost that I should be able to use a transform or invoke function to take advantage of that. That's why I started trying to use fusion.

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Re: [Boost-users] [Preprocessor] Relative Addresses in BOOST_PP_FILENAME_1
by Hossein Haeri 24 Jan '11

24 Jan '11

Hi TONGARI, > > #define BOOST_PP_FILENAME_1 "./Header.hpp" //1 > > #define BOOST_PP_FILENAME_1 ".\Header.hpp" //2 > > #define BOOST_PP_FILENAME_1 "Header.hpp" //3 > I have the same problem with you, I also use GCC 4.5.1, while <> works > fine but "" not. Strangely enough, <> doesn't work in my GCC either. (And, I'm not writing a precompiled header anyway.) Are you also using GCC under MinGW32? TIA, --Hossein

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Help me out from boost.log
by Steven Woody 23 Jan '11

23 Jan '11

Hi, I want to use boost.log and I succeeded in building it with bjam with Visual Studio 2005. But I quickly found I cannot use it. Below code are from the tutorial, #include <boost/log/core.hpp> #include <boost/log/trivial.hpp> #include <boost/log/filters.hpp> logging::core::init_log_to_file( keywords::file_name = "dsttest_%N.log", keywords::rotation_size = 10 * 1024 * 1024, keywords::time_based_rotation = sinks::file::rotation_at_time_point(0, 0, 0), keywords::format = "[%TimeStamp%]: %_%" ); logging::core::get()->set_filter( flt::attr<logging::trivial::severity_level>("Severity") >= loggin::trivial::debug ); but the compiler (vc++ 8.0) just complains: error C2653: 'logging' : is not a class or namespace name error C2653: 'keywords' : is not a class or namespace name ... I tried to use boost::log::logging, but it did not help. Then I decided to try the most simple code: BOOST_LOG_TRIVIAL(debug) << "hello boost.log"; it passed the compiler but not the linker: libboost_log-vc80-mt-gd-1_45.lib(trivial.obj) : error LNK2019: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::generic_category(void)" (?generic_category@system@boost@@YAABVerror_category@12@XZ) referenced in function "void __cdecl boost::system::`dynamic initializer for 'posix_category''(void)" (??__Eposix_category@system@boost@@YAXXZ) .... Please help me! Thanks in advance. -- Life is the only flaw in an otherwise perfect nonexistence -- Schopenhauer narke public key at http://subkeys.pgp.net:11371 (narkewoody(a)gmail.com)

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troubles with boost filtering streams
by Daniel Oberhoff 23 Jan '11

23 Jan '11

Hi, I am working on a matlab file reader/writer. Since matlab uses zip to compress variables I was thinking I could use the boost filtering streams with the zip filter to handle that. The use case is that there are zipped blocks inside the file, i.e. not the whole file is zipped but just parts. I am not sure how to handle that with boost, since I would need to start/stop zipping/unzipping at almost arbitrary points in the file. Also I have trouble working with filtering streams at all. As a baseline test I started substituting the fstream I was reading from with a boost filtering istream onto which I pushed the fstream. Reading works fine for a while and then breaks. What I noted is that the fstream tellg always lags behind the actual number of bytes read. also using the fitlering streams tellg breaks the whole stream. also seeking does not seem to work with the filtering stream. I need to seek quite often. seeking only happens when not unzipping. I tried seeking on the fstream instead. that worked up to some point(as stated above). I fear the seeking on the fstream breaks the filtering stream, but seeking on the filtering stream doesn't work. If anyone has pointers that would be great. Best Daniel

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Random permutations using boost::random_number_generator and std::random_shuffle.
by Matthew Gwynne 23 Jan '11

23 Jan '11

Hi, We need the ability to randomly permute some range, and we already have this functionality available in the computer algebra system Maxima. We use Maxima for numerous things, often implementing basic algorithms in it, then later writing more efficient versions in C++. The problem we have is that we'd like to be able to make sure that any function we write to randomly shuffle a range, matches up with the Maxima "random_permutation" function. We believe it uses the Mersenne twister (boost::mt19937) and Knuth shuffle algorithms, and so we thought to implement these in C++ using boost::uniform_distribution, boost:variate_generator etc. However, we have two questions (open problems): 1) How does boost::variate_generator interact with mt19937, and the distribution? Is this documented somewhere? In the attached code, it seems we can construct boost::uniform_distribution with any maximum value, and still the number generator returns values outside of that range? Is this really right? 2) What algorithm does std::random_shuffle implement? (Not boost related specifically but hopefully someone will know) Is this defined by the C++ standard? It doesn't seem to be the simple Knuth shuffle algorithm (starting from top of range to bottom or vice versa) as we implement in the attached code. If anyone could point me in the right direction, I'd very much appreciate it. Thanks Matthew Gwynne http://cs.swan.ac.uk/~csmg/ Code: #include <vector> #include <iostream> #include <algorithm> #include <iterator> #include <cassert> #include <boost/lexical_cast.hpp> #include <boost/random/mersenne_twister.hpp> #include <boost/random/uniform_int.hpp> #include <boost/random/variate_generator.hpp> #include <boost/random/random_number_generator.hpp> namespace { enum { errcode_parameter = 1 }; const std::string program = "RandomShuffle"; const std::string err = "ERROR[" + program + "]: "; const std::string version = "0.0.3"; const int default_seed = 1; typedef boost::mt19937 base_generator_type; base_generator_type base_rand_gen; inline void set_random(const int seed) { assert(seed >= 1); base_rand_gen.seed(seed); } const unsigned int default_N = 10; typedef std::vector<int> vec_t; inline void initialise(vec_t& a) { for (unsigned int i = 0; i < a.size(); ++i) a[i] = i+1; } inline void output(const vec_t& a) { for (unsigned int i = 0; i < a.size(); ++i) std::cout << a[i] << " "; std::cout << "\n"; } template <class RandomAccessIterator, class RandomNumberGenerator> inline void random_shuffle(const RandomAccessIterator first, const RandomAccessIterator last, RandomNumberGenerator& rand) { typedef typename std::iterator_traits<RandomAccessIterator>::difference_type difference_type; difference_type n = last - first; assert(n >= 0); if (n <= 1) return; for (RandomAccessIterator i = first; i != last-1; ++i,--n) { const difference_type r = rand(n); assert(r >= 0); assert(r < n); std::iter_swap(i, i+r); } assert(n == 1); } } int main(const int argc, const char* const argv[]) { if (argc > 3) { std::cerr << err << "\n At most two arguments are allowed " "(the seed for the random-number generator and the number of elements).\n"; return errcode_parameter; } const int seed = (argc == 1) ? default_seed : boost::lexical_cast<int>(argv[1]); const unsigned int N = (argc < 3) ? default_N : boost::lexical_cast<unsigned int>(argv[2]); vec_t V(N); typedef boost::uniform_int<> uniform_distribution_type; uniform_distribution_type uniform_distribution(0,std::numeric_limits<int>::max()); // is this correct??? typedef boost::variate_generator<base_generator_type&, uniform_distribution_type> generator_type; generator_type rand_gen(base_rand_gen, uniform_distribution); typedef boost::random_number_generator<generator_type> RandomNumberGenerator; RandomNumberGenerator rg(rand_gen); set_random(seed); std::cout << "Underlying random sequence:\n"; for (long n = V.size(); n > 1; --n) std::cout << rg(n) << " "; std::cout << "\n\n"; initialise(V); set_random(seed); std::random_shuffle(V.begin(), V.end(), rg); std::cout << "std::random_shuffle:\n"; output(V); initialise(V); set_random(seed); ::random_shuffle(V.begin(), V.end(), rg); std::cout << "::random_shuffle:\n"; output(V); }

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