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

How the boost documentation is generated?
by Peng Yu 09 Sep '08

09 Sep '08

Hi, I'm wondering how the boost documentation for different packages is generated consistently and with code snippets extracted from the source code. Can somebody give a pointer? Thanks, Peng

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Problem with iostreams and zlib
by Alfred Kohl 09 Sep '08

09 Sep '08

Hi! the gzip_decompressor sometimes fails with Z_BUF_ERROR wrapped in zlib_error(). I'm using boost-1.36.0 and zlib-1.2.3, both statically linked. Stream setup is as follows: std::ifstream filein("testfile"); boost::iostreams::filtering_streambuf<boost::iostreams::input> strbuf; strbuf.push(boost::iostreams::gzip_decompressor()); strbuf.push(filein); std::istream input(&strbuf); do { char buf[4096]; input.read(&buf, 4096); } while (input.gcount() > 0); For one particular file, read() will fail after reading about 2 MB (of 3 MB total file size). The file decompresses fine with external tools and contains mainly zeros. The error happens in (boost/iostreams/filter/zlib.hpp): bool zlib_decompressor_impl<Alloc>::filter ( const char*& src_begin, const char* src_end, char*& dest_begin, char* dest_end, bool /* flush */ ) { before(src_begin, src_end, dest_begin, dest_end); int result = inflate(zlib::sync_flush); after(src_begin, dest_begin, false); zlib_error::check(result); // <--- return result != zlib::stream_end; } src_begin and src_end both point to the same location! I'm not an expert with zlib but this looks wrong to me... Re-compressing the file with an external tool does not help. Any ideas? Cheers, Alfred. -- GMX Kostenlose Spiele: Einfach online spielen und Spaß haben mit Pastry Passion! http://games.entertainment.gmx.net/de/entertainment/games/free/puzzle/61691…

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[boost:regex]an compiler error when use boost1_36 in application
by gj_uestc 09 Sep '08

09 Sep '08

hi,all When I use "libboost_regex-iw-mt-s-1_36.lib" in my application , I got such compiler error "cannot open file 'stlport_static.5.1.lib'".Should I need to find stlport_static.5.1.lib and add it by my self? Is there any Macro that may let myself choose whether or not use the 'stlport_static.5.1.lib'? PS:The boost lib I used is compilered with ICU,Is there any chance that the 'stlport_static.5.1.lib' is brought by useage of ICU? Thanks Juan

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Re: [Boost-users] Catching boost::thread_interrupted
by rbock＠eudoxos.de 09 Sep '08

09 Sep '08

Hi, sorry, forgot to send the attachment in the original positing... Regards, Roland Hi, currently I am making my first steps using Boost.Thread (1.36.0). The interrupt feature looks very cool, so I tried to use it, but somehow failed to catch boost::thread_interrupted. The code is attached to this mail. I was expecting to see something like Thread 0x60b050 got interrupted Thread 0x60b3e0 got interrupted Instead I got Thread 0x60b050 caught something else Thread 0x60b3e0 caught something else Can somebody please enlighten me? Thanks and regards, Roland

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[Asio] Erratic results with io_service + deadline_timer
by John Zwinck 09 Sep '08

09 Sep '08

Today I tried using Boost.Asio to make a function get called at a particular time of day. My work included some tests, which usually passed but sometimes failed. I've boiled it down below. I'm using gcc 4.0.3 and Boost 1.35 on Linux 2.6.22 (Ubuntu Dapper 32-bit i686, quad-core CPU). I compiled the following code with g++ -lboost_thread -lboost_date_time -lboost_system : #include <boost/system/error_code.hpp> #include <boost/thread/thread.hpp> #include <boost/asio/io_service.hpp> #include <boost/asio/deadline_timer.hpp> #include <boost/date_time/posix_time/posix_time.hpp> using namespace boost; using namespace boost::asio; using namespace boost::posix_time; bool g_called = false; io_service g_svc; void func(boost::system::error_code ec) { g_called = true; } void work() { for(;;) { g_svc.run(); } } int main() { thread thr(work); #ifdef FAIL // if defined, causes program to always assert this_thread::sleep(milliseconds(1)); #endif deadline_timer tmr(g_svc, second_clock::local_time() + seconds(1)); tmr.async_wait(&func); // expected to wait 1 second then call func this_thread::sleep(milliseconds(1500)); assert(g_called); } I think my first issue was that I didn't recognize the need to call io_service::run in a loop. The docs<http://www.boost.org/doc/libs/1_35_0/doc/html/boost_asio/reference/io_servi…>don't make this clear at all, stating that it will "Run the ... event processing loop," but I figured from reading the source that the loop in my own code was needed. Anyway, that didn't fix it. What I'm expecting here is that my callback function will be invoked about a second after registration, and it will set the flag which is then checked half a second later. When compiled as-is, this (usually) works. However, when compiled with -DFAIL, which just adds a tiny sleep in a place I'd think it would not matter, it fails always. Surely I'm doing something wrong. Or is the combination of this (new) library and my system just not working correctly (something I rather doubt given my past experience with Boost)?

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Re: [Boost-users] [boost:regex]an compiler error when use boost1_36 inapplication
by gmail 09 Sep '08

09 Sep '08

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Is there a function to compute the determinant of a square matrix?
by Peng Yu 09 Sep '08

09 Sep '08

Hi, boost has ublas. I'm wondering if there is a function to compute the determinant of a square matrix in boost? Thanks, Peng

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mpl::transform<...> --- compile error: is not derived from type
by e r 09 Sep '08

09 Sep '08

hi, here's the problem i have: struct my{ template<typename UInt> struct apply{ typedef mpl::int_<UInt::value> type; }; }; template<int First,int Last> struct id_range{ typedef mpl::transform< mpl::range_c<int,First,Last> , my , mpl::back_inserter< mpl::vector<> > >::type type; /home/er/cpp/boost/random/mcmc/id_range.hpp|32|error: type ‘boost::mpl::transform<boost::mpl::range_c<int, First, Last>, boost::random::mcmc::<unnamed>::my, boost::mpl::back_inserter<boost::mpl::vector<mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na> >, mpl_::na>’ is not derived from type ‘boost::random::mcmc::id_range<First, Last>’| however, for example, this --instead-- compiles fine: struct id_range{ typedef mpl::transform< mpl::range_c<int,1,3> , my , mpl::back_inserter< mpl::vector<> > >::type type; }; any suggestion appreciated. thanks!

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[dataflow][review] loading Dataflow.Signals components from shared libraries
by Stjepan Rajko 09 Sep '08

09 Sep '08

In the Dataflow library / Dataflow.Signals layer review discussions, a few people have mentioned the potential usefulness of loading components at runtime (e.g., from a shared library). I put together a small example of how this could be done for Dataflow.Signals components using the (prototype) Dataflow.Blueprint layer and the Extension library: http://svn.boost.org/svn/boost/sandbox/SOC/2007/signals/libs/dataflow/examp… The component_add.cpp file contains the implementation of a component (that adds two numbers and outputs the result), and the code required to access it through an Extension factory_map. The extension_example.cpp file loads the shared library created from component_add.cpp, instantiates the provided component, and uses it to complete a network. The Blueprint layer is still under development (and has somewhat ugly syntax), but I hope this example can still demonstrate some future possibilities of the Dataflow library with regards to loading components at run-time. It has been tested to work with MSVC 2005. Regards, Stjepan

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[boost-users][DateTime] crash with time_duration
by Igor R 08 Sep '08

08 Sep '08

Hi, The following code crashes (MSVC2005, boost1.36): //.... time_duration td = hours(25); cout << td; It seems that operator <<() uses to_tm() function, and the latter sets tm_hour = 25, which causes an assertion in CRT _expandtime() and program termination. Is this desired behavior / known issue / unknown bug? Thanks, Igor'.

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