November 2007 - Boost-users

boost::filesystem drive letters?
by Jay Lawrence 29 Nov '07

29 Nov '07

Hi all, After a bit of searching around I am pretty sure I can't get a list of available drive letters with this library, does anyone know of a way to achieve? (platform independant would be ideal) Best, Jay

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mpl::vector to boost::function
by Michael Linck 29 Nov '07

29 Nov '07

This my first attempt at using the boost::mpl library, so I may be off on the wrong track. If that's the case, please let me know and I'll come up with a different way to solve my problem. This seemed like a good practice case though. I'm trying to write a class that can test a function (eventually any function). The idea is that you specialize some number of arguments ( up to ten ) and then hand it a function. Then you feed "test cases" into it, which consist of arguments and an expected result. It seemed to me that TMP might be the key avoid having to write the template class 10 times (once for each number of template parameters). I thought it would look something like this: template<typename TestResultTA, typename TestInput1TA, typename TestInput2TA = void, typename TestInput3TA = void, typename TestInput4TA = void, typename TestInput5TA = void, typename TestInput6TA = void, typename TestInput7TA = void, typename TestInput8TA = void, typename TestInput9TA = void, typename TestInput10TA = void> class TestScenario { typedef boost::mpl::vector<TestInput1TA, TestInput2TA, TestInput3TA, TestInput4TA, TestInput5TA, TestInput6TA, TestInput7TA, TestInput8TA, TestInput9TA, TestInput10TA> TenArgs; typedef typename boost::mpl::find<TenArgs, void>::type FirstUnusedArg; typedef typename TenArgs::erase<TenArgs, FirstUnusedArg, TenArgs::end> JustTheArgs; // I know this is non-sense but what should go here? typedef boost::function2<TestResultTA, JustTheArgs> TestFunctionTS; . . . So far so good. I have a type that is a vector of the subset of template arguments that are initialized. I've thought about maybe trying to use #defines and recursion to create a template argument string for the boost::function, or something. That seems totally hideous, likely to fail, and my coworkers wouldn't accept it as maintainable code anyway just because of the #defines' presence. Is there an elegant way to go from a vector of types to an argument list for another template? I would have to use this mechanism to also specialize various other functions, like the one that accepts sets of arguments, and some kind of struct for holding those arguments at run-time. Thank you, mike

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suspected bug
by Laurence Bunnage 29 Nov '07

29 Nov '07

I am currently maintaining a project written using Borland C++ Builder version 6 build 10.166 and boost version 1.32. I found I had a reoccuring problem in my code whereby the output from lexical_cast<string>(any_double) was not at the precision I was expecting. It started off OK, but after a while it changed. I have tracked it down to some of my code which I simplified to that shown below. The first cast, in the try block, works correctly with the output value d = 5.0 and no assert The second cast, in the catch statement, returns a value of d = 5.00000013628211 and asserts. With the assert removed, all subsequent calls to lexical_cast continue to give similar results. try { double d = boost::lexical_cast<double>(boost::lexical_cast<std::string>(5.0)); assert(d == 5.0); throw std::runtime_error("Not enough points in peak"); } catch (std::exception& e) { double d = boost::lexical_cast<double>(boost::lexical_cast<std::string>(5.0)); assert(d == 5.0); } I have searched the boost website for similar problems and have not found anything (doesn't mean it's not there, just I haven't found it) Any help, especially a solution or work around would be greatly appreciated. NOTE at this time, due to the current state of the project, I would prefer not to have to upgrade to a newer version of the boost library. Laurence Bunnage Software Engineer e-mail: Laurence.Bunnage(a)teraview.com <mailto:Laurence.Bunnage@teraview.com> TeraView Limited Registered in England Registered Office: Platinum Building, St John's Innovation Park, Cambridge CB4 0WS Registered Number: 04126946 VAT Number: 770 8883 84

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boost-users [pointer containers] stl set_unions
by chun ping wang 29 Nov '07

29 Nov '07

is it possible to use stl set_unions with ptr_container or do I have to hand roll my own. if yes what inserter should i use or how would i use two containers having pointer of int ptr_vector<int> a1; ptr_vector<int> a2; have a1 union a2 and store in a3.

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ERROR on serialization for vector<shared_ptr<T> > with PIMPL idiom
by Youhei Murakami 29 Nov '07

29 Nov '07

Hello everyone. I tried to serialize vector<shared_ptr<T> > that is held by pimpl but I met to a lot of error. If someone who knows the resason for it exists, please teach me the reason. source code is below. Compiled using visual studio 2005 sp1 in WindowsXP64bit. boost-1_34_1 source code has been attached. // test_serialization.cpp : Defines the entry point for the console application. // //#include "stdafx.h" #include <iostream> #include <fstream> #include <cstdlib> #include <typeinfo> #include <memory> #include <algorithm> #include <vector> #include <map> #include <boost/any.hpp> #include <boost/shared_ptr.hpp> #include <boost/intrusive_ptr.hpp> #include <boost/ptr_container/ptr_vector.hpp> #include <boost/thread.hpp> #include <boost/tuple/tuple.hpp> #include <boost/tuple/tuple_comparison.hpp> #include <boost/tuple/tuple_io.hpp> #include <boost/type_traits.hpp> #include <boost/optional.hpp> #include <boost/serialization/serialization.hpp> #include <boost/serialization/string.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/list.hpp> #include <boost/serialization/map.hpp> #include <boost/serialization/set.hpp> #include <boost/serialization/deque.hpp> #include <boost/serialization/shared_ptr.hpp> #include <boost/serialization/scoped_ptr.hpp> #include <boost/serialization/split_member.hpp> #include <boost/serialization/version.hpp> #include <boost/serialization/base_object.hpp> #include <boost/serialization/tracking.hpp> #include <boost/serialization/is_abstract.hpp> #include <boost/serialization/nvp.hpp> #define BOOST_LIB_NAME boost_serialization #include <boost/config/auto_link.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp> #include <boost/archive/xml_iarchive.hpp> #include <boost/archive/text_woarchive.hpp> #include <boost/archive/text_wiarchive.hpp> using namespace std; using namespace boost; using namespace boost::serialization; namespace test{ class holder { struct Impl { Impl() : x(0.0), y(0.0), message(wstring(L"blank")) { vec.push_back(shared_ptr<int>( new int(1) )); vec.push_back(shared_ptr<int>( new int(2) )); vec.push_back(shared_ptr<int>( new int(3) )); } Impl( double ax, double ay, const wstring &am, const vector<shared_ptr<int> > &av ) : x(ax), y(ay), message(am), vec(av) { } double x, y; wstring message; vector<shared_ptr<int> > vec; private: friend class serialization::access; template <class Archive> void serialize( Archive &ar, const unsigned long version ); }; shared_ptr<Impl> impl; public: holder() : impl( new Impl ) {} holder( double ax, double ay, const wstring &am, const vector<shared_ptr<int> > &av ) : impl( new Impl(ax, ay, am, av) ) {} private: friend class serialization::access; template <class Archive> void serialize( Archive &ar, const unsigned long version ) { ar & impl; } }; template <class Archive> void holder::Impl::serialize(Archive &ar, const unsigned long version ) { ar & x; // ok ar & y; // ok ar & message; // ok ar & vec; // error : if remove this line, this source code will move file. } template void holder::serialize<archive::text_woarchive>( archive::text_woarchive &ar, const unsigned long version ); template void holder::serialize<archive::text_wiarchive>( archive::text_wiarchive &ar, const unsigned long version ); template void holder::Impl::serialize<archive::text_woarchive>( archive::text_woarchive &ar, const unsigned long version ); template void holder::Impl::serialize<archive::text_wiarchive>( archive::text_wiarchive &ar, const unsigned long version ); }; // end namespace test2 int _tmain(int argc, _TCHAR* argv[]) { using namespace test; { wofstream ofile( L"hierarchy.txt" ); archive::text_woarchive oa(ofile); holder h; oa << (const holder&)h; ofile.close(); holder ih; wifstream ifile( L"hierarchy.txt" ); archive::text_wiarchive ia(ifile); ia >> ih; ifile.close(); }; getchar(); return 0; }

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Library & Header file paths on Windows with Boost
by jayc.lawrence＠gmail.com 29 Nov '07

29 Nov '07

Hi, This post is not really 100% boost specific but I am trying to compile using boost libraries and I thought I'd give this newsgroup a shot. I want to know what have others done to avoid the circles I've gone in to get this simple program compiled. I compiled boost to "c:\boost\" and I have my MinGW installed in "c:\devel\MinGW\" however if I attempt to compile using: g++ -v -Ic:\boost\ simplels.cpp -Lc:\boost\lib\ -lboost_filesystem-mgw34-d-1_34_1 It would result in failing to include the header files and I noticed: ignoring nonexistant directory "c:/boost/" Am I going crazy here or does it appear that the compiler cannot access anything beyond its default include paths? So I tested it out... I made a directory in MinGW called "test" and used the following command line: g++ -v -Ic:\devel\MinGW\test\ headertest.cpp And still no header files.. It resulted in: ignoring nonexistant directory "c:/devel/MinGW/test/" I thought i'd add it my windows %path% too but still had exactly the same problem. So I finally resorted to putting the header files in the MinGW/GCC include directory and the library files in the MinGW/GCC library directory.. et voila! it compiled. But this isn't ideal for me, anyone got any tips where I'm going wrong here cause sure it's compiling now but.. I like to keep things relatively tidy on here! Best, Jay

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Boost Asio within dotnet app : "Acces denied"
by Guillaume Baranger 29 Nov '07

29 Nov '07

Hello, I need to create a server in dotnet application. I am using boost 1.33.1, asio 0.3.8 and vc++ 7.1 . The following code raises an "access denied" exception in a dotnet application. I have tested the same simple code in native c++ application, and it works. Do you have any idea how to resolve my problem? Is there a way to use asio in a dotnet application? try { asio::io_service io_service; asio::ip::tcp::acceptor acceptor(io_service); asio::ip::tcp::endpoint endpoint(asio::ip::tcp::v4(), 35454); acceptor.open(endpoint.protocol()); acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true)); // exception thrown here acceptor.bind(endpoint); // exception thrown here if previous line in comment acceptor.listen(); } catch(std::exception& excep) { MessageBox::Show(excep.what(),S"",MessageBoxButtons::OK,MessageBoxIcon::Erro r); } Regards, Baranger Guillaume

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Trying to get Boost.Interprocess going on OS X 10.5.1
by Stefan Arentz 29 Nov '07

29 Nov '07

I checked out boost trunk from svn and tried to compile a simple boost.interprocess example. Unfortunately it fails at a rather unexpected place: % c++ doc_message_queueA.cpp -Itrunk -o doc_message_queueA % ./doc_message_queueA Assertion failed: (res == 0), function lock, file trunk/boost/interprocess/sync/posix/interprocess_mutex.hpp, line 116. zsh: abort ./a The error code is 22, EINVAL. I'm on OS X 10.5.1, maybe that is too new, or not yet tested? S.

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[Boost.Array] surprising performance issue
by Bryan Green 29 Nov '07

29 Nov '07

Hello, I've discovered a situation where using boost::array results in a 2-fold performance degradation over other array types, including C arrays, tr1::array, and a simple handwritten array class. While the tr1::array performs well, I was suprised to find that it pads the array, so sizeof(tr1::array<3,float>) == sizeof(tr1::array<4,float>). Is that a requirement of tr1::array? Anyway, the performance problem can be seen using Intel C++ (v9.1) on the Itanium platform, using '-O3' optimization. I'm forced to take boost::array out of my computation's inner loop. Is this a previously known issue? Any ideas why this performance discrepancy might exist? Thanks, Bryan Green

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[dataflow] version 0.8.1: runtime reflection, dataflow network modeling via BGL...
by Stjepan Rajko 29 Nov '07

29 Nov '07

Hello everyone, I have uploaded a new version of the dataflow library to the vault (in the Dataflow directory), and updated the docs at: http://dancinghacker.com/code/dataflow/ The new version introduces the Dataflow.Blueprint layer, which provides runtime reflection of components/ports, as well as modeling and analysis of dataflow networks via BGL. This new layer is still full of hacks, its documentation is limited to a messy example, but I'm excited about having started it. This version also has some documentation updates and some additional examples (such as a little image processing dataflow example using Boost.GIL). If anyone is interested, my roadmap to requesting review looks like this: * add lots and lots of docs. * bring the Dataflow.Blueprint to some reasonably usable state. * move functionality from the overabused Port-related concepts into the Component concept, which should clean up and simplify the concepts dramatically. With this, I think the library will be in decent shape to request a review (it will have one dataflow framework modeling the generic concepts - Dataflow.Signals, and one layer built on top of the concepts, - Dataflow.Blueprint). My goal is to get there in the next month (which is only 5 months after GSoC close! :-)) By the time it actually gets to be reviewed, I hope to also add in another dataflow framework that would in some way address the things currently missing from this library (there are many). Any feedback is appreciated. Thanks to Phil Endecott, Pavel Vozenilek, John Torjo, Roland Schwarz and Neal Becker for their helpful feedback on the previous version. Regards, Stjepan

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