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[python] Need help with embedding
by Robert Dailey 18 Feb '08

18 Feb '08

Hi, Below is my source code. What I'm trying to do is expose a C++ function to the embedded interpreter so I may call it from scripts executed by that embedded interpreter. Right now it just crashes with what seems to be an access violation against NULL: SOURCE: --------------------------------------------------------------------------- static void DoFoo() { int breakhere = 0; } using namespace boost; BOOST_PYTHON_MODULE(pythontest) { python::def( "DoFoo", DoFoo ); } void SetupPython() { if( PyImport_AppendInittab( "pythontest", NULL ) != -1 ) { int breakhere = 0; } else { int breakhere = 0; } python::object pytest = python::exec_file( "pythontest.py" ); } void BeginPythonTest() { Py_Initialize(); SetupPython(); } The pythontest.py file does nothing more than call *DoFoo()*. I've been looking at the *boost\libs\python\example\quickstart\embedding.cpp *, however it isn't very helpful and hard to read. In addition it calls a function named "initembedded_hello" which is nowhere to be found... This won't even compile? Any help is greatly appreciated!

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lock free / wait free
by jono 18 Feb '08

18 Feb '08

hi all, i was wondering if there are any formal initiatives in the boost community to provide 'lock free' data structures using CAS (compare and swap)? in particular, this looks promising... "Instead of providing a separate atomic smart pointer, we propose additions to shared_ptr's interface to address this use case. A typical example scenario — a "lock-free" reader/writer pattern — that takes advantage of this functionality is outlined below:..." [http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2007/n2297.html#atomic] is this likely to happen this year? i've seen some other discussion, such as http://www.nabble.com/Lock-free-atomic_shared_ptr%3CT%3E--td14958758.html i've used the Microsoft interlocked API's in a past (audio processing) project, but i'm developing a video pipeline for Linux/Win32 and it would be a huge 'boost' to be able to eliminate some locking and have deterministic real time. if that were introduced via the shared_ptr interface, i'd be over the moon. unfortunately, i don't have the skills to really contribute to this initiative, but i wld like to add my voice to those who might find a use for it! cheers, jono

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WG: Boost Build
by Klett, Stefan 18 Feb '08

18 Feb '08

Hi fellow list subscribers, The last days I have been busy to build a build-environment for a library project with boost build - I am new to boost and have no previous experience with boost build - what may account for the following problems I ran into The proposed structure of the library project is like this: Project-root | \ \ \ Include src doc examples / | testcase1 testcase2 ... Now I need some help to make bjam perform the following tasks: 1) build the library (this one works already) 2) generate a doxygen based documentation out of the the *.cpp files in src 3) build the testcases in the "testcaseX" directories For the time being I'm lacking the knowledge how to build targets (the above tasks separately - I tried to use the "explicit" keyword but it seems that missed something - bjam works trough all targets given in the Jamroot file which I placed in the "project-root" directory - could somebody please give me an example how to use targets and "explicit" correctly Further I need an hands on example how to get along with the doxygen documentation - my efforts up to now look like this - but this actually seems to do nothing at all Import doxygen : doxygen ; doxygen.doxygen doc : geneva : [ glob include/*.h ] #: requirements <include>include : ; The Question is : how do I extract the information from the files in src and write the doxy docu to doc ? And last but not least : how is the correct syntax for building sources in subdirectories - where have I to put the Jamfiles and how to I tell bjam to look for them ? Many Thanks in advance Best regards Stefan -------------------------------------------------------- Stefan Klett (Dipl. Informatiker) | E-mail: stefan.klett(a)kit.edu Forschungszentrum Karlsruhe / KIT | Web: http://www.fzk.de SCC Steinbuch Centre for Computing| Phone: +49 (0)7247 828649 Hermann-von-Helmholtz-Platz 1 | Fax: +49 (0)7247 824972 D-76344 Eggenstein-Leopoldshafen | Mobile: +49 (0)176 20317250 -------------------------------------------------------------------

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Boost.IOStreams and Custom filters on strings
by Stefan Arentz 18 Feb '08

18 Feb '08

I've written a really simple aggregate_filter that runs the world famous and highly secret ROT13 encryption. This filter works fine when I use a file_sink and file_source. But I really just want to run this on a bunch of string buffers. Unfortunately it does not work, the destination string is always empty. Does anyone understand why? Here's the code, tested against Boost 1.34.1 on OS X 10.5.1: #include <iostream> #include <memory> #include <string> #include <boost/iostreams/copy.hpp> #include <boost/iostreams/device/back_inserter.hpp> #include <boost/iostreams/filter/aggregate.hpp> #include <boost/iostreams/filtering_stream.hpp> template< typename Ch, typename Alloc = std::allocator<Ch> > class basic_rot13_filter : public boost::iostreams::aggregate_filter<Ch, Alloc> { private: typedef boost::iostreams::aggregate_filter<Ch, Alloc> base_type; public: typedef typename base_type::char_type char_type; typedef typename base_type::category category; typedef std::basic_string<Ch> string_type; public: basic_rot13_filter() { } private: typedef typename base_type::vector_type vector_type; void do_filter(const vector_type& src, vector_type& dest) { for (size_t i = 0; i < src.size(); ++i) { dest.push_back(src[i] + 13); } } }; typedef basic_rot13_filter<char> rot13_filter; typedef basic_rot13_filter<wchar_t> wrot13_filter; int main() { std::string src = "SourceText"; boost::iostreams::filtering_istream in; in.push(boost::make_iterator_range(src)); std::string dst; boost::iostreams::filtering_ostream out; out.push(rot13_filter()); out.push(boost::iostreams::back_inserter(dst)); boost::iostreams::copy(in, out); std::cout << dst << std::endl; return 0; }

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boost::serialization and platform portability
by Mark Schlegel 18 Feb '08

18 Feb '08

Boost User list: I have a question about boost::serialization and portability. When I read in the overview for this feature at http://www.boost.org/libs/serialization/doc/overview.html point 7 states that "Data Portability - Streams of bytes created on one platform should be readable on any other". I'm trying to clear up how far portability goes. I've tested serialization on two different hardware platforms (Intel Linux with Boost 1.34.1 and Sparc Solaris with Boost 1.33.1) which have different endians. The archiving writes and reads fine as long as the reading is done on the newer or equal version of Boost. Basically I wrote a serialization file with boost::archive::text_oarchive on the Solaris box and ftped the file to the Linux host and read it in fine. But going the other way (1.34.1 -> 1.33.1) aborted which is understandable because a archive version level change (3 vs 4) existed between those. So is readability assured by serialization as long as you're going from an older or equal version of boost? We can handle our maintaining the very latest boost version in our code and customers would send us their archives for testing and they'd either have the same or older version of boost in their copy. Their code would never be newer than ours. If this is obeyed will their archives always be readable by our code? Mark

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BGL and interactive visualization
by mbn 18 Feb '08

18 Feb '08

Hi, Maybe this is an old topic but I can't find related answers. I have some data containing certain "entities" related to others by one or more attributes. For example, Alice's cat may be connected to Bob's dog because both are named "Bill". Also, they can be connected because they live in the same county. Furthermore, Bob's dog can be connected to Chuck's bird because they are of the same color Something like this: (A'sC)--------------(B'sD)-----------------(C'sB) Name=Bill Color=Beige County=CD The issue is, the attributes connecting entities can be hundreds or even thousands, so creating a graphviz file showing all those connecting attributes in the edges will result in a mess. Instead, I would like to create an application such that only the vertices (with a label inside) and the edges (without nothing) are initially shown, and when the user double clicks on a specific edge then some window can appear showing all the attributes causing X and Y to be connected in the graph. I know I can create the graphs using BGL, but once I have the graphs I do not know what library to use in order to visualize it Can somebody help? Perhaps there is a different/better way of doing the same with a different tool like GraphML + Some Visualization program? Thanks, Mark -- View this message in context: http://www.nabble.com/BGL-and-interactive-visualization-tp15514275p15514275… Sent from the Boost - Users mailing list archive at Nabble.com.

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[boost-users] [bjam BOOST_AUTO_LINK_NOMANGLE]
by chun ping wang 18 Feb '08

18 Feb '08

I want to build msvc library by defining BOOST_AUTO_LINK_NOMANGLE but i also want to specify multithreaded build. Example I want my thing to auto link to boost_python-mt.lib Is their a way to do this. BOOST_AUTO_LINK_NOMANGLE only links to boost_python.lib Thanks.

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random variate_generator, call_traits...
by e r 18 Feb '08

18 Feb '08

Hi All, I have classes A and B as random distributions i.e. they have a member function operator()(UniformRandomNumberGenerator&). I choose to make UniformRandomNumberGenerator a class template instead of a member function template (why? because in my non-simplified code A::operator()(...) is virtual). B has a member variable of type A that it uses for its implementation. Passing UniformRandomNumberGerator& into the nested object's A::operator()(...) causes a reference to reference problem that I solve with call_traits. fine? I want to wrap a boost::variate_generator around UniformRandomNumberGenerator and B. The variate_generator does not pass UniformRandomNumberGenerator& to A::operator()(...) but - i guess - a decorated version of it. so I have to specify A<Decoration> instead of A::<UniformRandomNumberGenerator> and likewise for B. I don't like this manual fix (I have to look at the compiler errors to figure out Decoration). Maybe I could overload A and B's operator()(...) with something like operator()(Decoration<UniformRandomRandomNumberGenerator>) but have not succeeded. Any better suggestion? #include <boost/call_traits.hpp> template<class UniformRandomNumberGenerator> class A{ public: typedef UniformRandomNumberGenerator urng_type; typedef double input_type; typedef double result_type; typedef urng_type argument_type; result_type operator()(argument_type u){return u();}; }; template<class UniformRandomNumberGenerator,template<class> class Impl> class B{ public: typedef UniformRandomNumberGenerator urng_type; typedef Impl<urng_type> impl_type; typedef double input_type; typedef double result_type; typedef typename impl_type::argument_type impl_argument_type; typedef typename boost::call_traits<impl_argument_type>::reference argument_type; result_type operator()(argument_type u){return impl(u);}; private: impl_type impl; }; #include "A.hpp" #include <boost/random.hpp> #include <boost/random/variate_generator.hpp> #include <boost/random/uniform_real.hpp> typedef boost::mt19937 urng_type; typedef boost::uniform_real<> rdu01_type; typedef boost::variate_generator<urng_type&,rdu01_type> urng01_type; typedef A<urng01_type> a0_type; typedef B<urng01_type,A> b0_type; typedef boost::variate_generator<urng01_type&,b0_type> rg0_type; typedef boost::uniform_01<boost::random::detail::pass_through_engine<urng01_type&>,double> pass_through_engine_type; //manual fix, far from ideal typedef A<pass_through_engine_type> a1_type; typedef B<pass_through_engine_type,A> b1_type; typedef boost::variate_generator<urng01_type&,b1_type> rg1_type; int main(){ urng_type urng; rdu01_type rdu01; urng01_type urng01(urng,rdu01); b0_type b0; std::cout << b0(urng01) << std::endl; //OK // rg0_type rg0(urng01,b0); // std::cout << rg0() << std::endl; // Error no match for call to ‘(B<boost::variate_generator<boost::random::mersenne_twister<unsigned int, 32, 624, 397, 31, 2567483615u, 11, 7, 2636928640u, 15, 4022730752u, 18, 3346425566u>, boost::uniform_real<double> >, A>) (boost::uniform_01<boost::random::detail::pass_through_engine<urng01_type&>, double>&)’ candidates are: double B<UniformRandomNumberGenerator, Impl>::operator()(typename boost::call_traits<typename Impl<UniformRandomNumberGenerator>::argument_type>::reference) [with UniformRandomNumberGenerator = boost::variate_generator<boost::random::mersenne_twister<unsigned int, 32, 624, 397, 31, 2567483615u, 11, 7, 2636928640u, 15, 4022730752u, 18, 3346425566u>, boost::uniform_real<double> >, Impl = A] b1_type b1; rg1_type rg1(urng01,b1); std::cout << rg1() << std::endl; //OK return 0; }

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Re: [Boost-users] Another desperate request for help with a simple IOStreams sink and filter
by Chad Walters 18 Feb '08

18 Feb '08

Jonathan, A couple thoughts: 1. One of the first confusions that I naively had when I first approached the library was that classes that had close() methods did not necessarily model Closable. I am not sure if this means that "Closable" is a bad name and should be changed, but it might be worth calling out this distinction more pointedly in the documentation. 2. Perhaps for filtering streams, it would be best to make sure that closing the stream would close all the filters and flush the device. Would that solve this issue? Or is that already the current behavior? Chad Jonathan Turkanis wrote: The problem is that filtering_stream does not model Closable, so close() is a no-op. This is counterintuitive and probably represent a less than ideal design, but when I wrote the library I couldn't think of a satisfactory way to define close() for a filtering stream. You might think that the way to define close() would simply be to close all the filters and devices in the chain. Unfortunately, this is not correct. The reason is that while filters are designed to be reusable, devices are in general one-use only. For example, when a compression filter is closed, it is expected to be in a state where it can be used to compress a fresh stream of data. But when a file is closed, it is not reset to the state it was in when it was first opened: it has to be manually reopened with a new user-provided pathname. So simply closing all the filters and devices in the chain would leave the chain in an unusable state. The closest I could come to defining a non-trivial close() for filtering_streams was to have close() call pop() -- in effect, closing all the filters and discarding the final device. However, my feeling was that this behavior would be considered counterintuitive. I knew this could cause problems with copy, but I decided to wait for user feedback before making any changes. The issue never came up, and I forgot about it until now. It could be that not many are using the library, as you suggest, or that people discovered that you can solve the problem by calling reset() or pop() -- as you heard on the IRC channel -- and never bothered to bring it up on this list. I've created a ticket for this issue: http://svn.boost.org/trac/boost/ticket/1624. At the very least it should be a FAQ. > Is anyone actually using the library? I can't believe I'm the first > finding a bug like this in a 5 year old library. > > S. -- Jonathan Turkanis CodeRage http://www.coderage.com

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Gentoo: recent emerge gives me PIC errors
by Jason Weber 18 Feb '08

18 Feb '08

On my last emerge, I believe I got a new set of boost libs (amd64). Now my project is getting a PIC problem. All my code use compiles with -fPIC, so is this no longer the case with boost on Gentoo and is there a way to turn it on? I tried some various USE flags but nothing seems to make a difference. Or is that not the problem? ccache g++ -fPIC -DFE_USE_SSE=2 -msse2 -march=k8 -pipe -shared -o /mnt/raid/symroot/proj/fe/main/lib/x86_64_linux_debug/libfePlatform.so -DFE_DOUBLE_REAL=0 -ftemplate-depth-60 -ansi -D_REENTRANT -D_POSIX_REENTRANT_FUNCTIONS -DZT_POSIX -pipe -D_DEBUG -g2 -Wall -DGCC_HASCLASSVISIBILITY -fvisibility-inlines-hidden -fvisibility=hidden -Winvalid-pch -I/mnt/raid/symroot/proj/fe/main/ext -I/usr/X11R6/include -I/mnt/raid/sym/root/proj/fe/main/src -I/mnt/raid/symroot/proj/fe/main/lib/x86_64_linux_debug -I/mnt/raid/symroot/proj/fe/main/lab /mnt/raid/symroot/proj/fe/main/obj/x86_64_linux_debug/src/platform/debug.o /mnt/raid/symroot/proj/fe/main/obj/x86_64_linux_debug/src/platform/DL_Loader.o /mnt/raid/symroot/proj/fe/main/obj/x86_64_linux_debug/src/platform/DualString.o /mnt/raid/symroot/proj/fe/main/obj/x86_64_linux_debug/src/platform/Exception.o /mnt/raid/symroot/proj/fe/main/obj/x86_64_linux_debug/src/platform/Result.o /mnt/raid/symroot/proj/fe/main/obj/x86_64_linux_debug/src/platform/String.o /mnt/raid/symroot/proj/fe/main/obj/x86_64_linux_debug/src/platform/System.o /mnt/raid/symroot/proj/fe/main/obj/x86_64_linux_debug/src/platform/SystemTicker.o -ldl -L/mnt/raid/symroot/proj/fe/main/lib/x86_64_linux_debug -ansi -lpthread -lrt -pipe -lm -lc -lcrypt -ldl -lboost_regex-mt -lboost_thread-mt -lboost_filesystem-mt -L/mnt/raid/symroot/proj/fe/main/lib/x86_64_linux_debug -L. -L/home/symhost/sym/bulk/amd64obj/fe/lib/x86_64_linux_debug /usr/lib/gcc/x86_64-pc-linux-gnu/4.1.2/../../../../x86_64-pc-linux-gnu/bin/ld: /mnt/raid/symroot/proj/fe/main/obj/x86_64_linux_debug/src/platform/String.o: relocation R_X86_64_PC32 against `boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string <char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::find()' can not be used when making a shared object; recompile with -fPIC /usr/lib/gcc/x86_64-pc-linux-gnu/4.1.2/../../../../x86_64-pc-linux-gnu/bin/ld: final link failed: Bad value collect2: ld returned 1 exit status

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