November 2010 - Boost-users

MSVC Visualizers Update
by Filip Konvička 28 Jul '11

28 Jul '11

Hi all, I've just updated the Boost visualizers wiki page at https://svn.boost.org/trac/boost/wiki/DebuggerVisualizers I updated the visualizer for Boost.MultiIndex, which did not work since Boost 1.35. I also added new visualizers for Boost.DateTime (ptime and time_duration) and a simple boost::shared_ptr visualizer. The visualizers are available for checkout via SVN at https://svn.boost.org/svn/boost/sandbox/boost_docs/subprojects/DebuggerVisu… Cheers, Filip

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[multi-array] Extracting dimension information from a multi-array
by Ryan McConnehey 15 Jul '11

15 Jul '11

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Asio unhandled exception
by Łukasz Majewski 20 May '11

20 May '11

Hello, I created a server single thread async (linux) and clinet (win). Every time client is close while server is writing to the socket connected to this client exception appears: terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::system::system_error>>' what(): Transport endpoint is not connected Aborted and server is terminated. I dont know why this exception is unhandled. int main( int argc, char** argv ) { try { boost::asio::io_service io_service; quotation_server server( io_service ); while ( true ) { try { io_service.run(); } catch( ... ){} } } catch ( std::exception& e ) { LOG << e.what() << std::endl; } catch( ... ) { LOG << "Unexpected exception" << std::endl; } return 0; }

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vs 2010 can't find correct boost lib version?
by Li, Tieniu 30 Mar '11

30 Mar '11

I built boost with visual studio 2010. Libraries of *-vc100-* are generated correctly. When trying to using boost.thread, VS 2010 generated error message: can't find *-vc90-*.lib. Any idea and fixing? Thanks a lot.

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[BGL] Separating twin vertices
by Shaun Jackman 18 Mar '11

18 Mar '11

Hi, I have a directed graph where every vertex has a twin vertex. It is known ahead of time which pairs of vertices are twins. I want to remove as few vertices as possible from the graph such that no vertex and its twin is in the same connected component. Could someone suggest an appropriate algorithm? I've just started delving into the BGL. So far I'm suitably impressed! Cheers, Shaun

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Re: [Boost-users] multi_array and variants
by Alle Meije Wink 07 Feb '11

07 Feb '11

Dear Kris, thanks for your reply. > > What I now have is a class bisArray: > > ... > > template<typename T> > > class bisArray: public bisObject { > > typedef boost::variant > > < boost::multi_array_ref<T, 1>, > > boost::multi_array_ref<T, 2>, > > boost::multi_array_ref<T, 3>, > > boost::multi_array_ref<T, 4>, > > boost::multi_array_ref<T, 5>, > > boost::multi_array_ref<T, 6>, > > boost::multi_array_ref<T, 7>, > > boost::multi_array_ref<T, 8>, > > boost::multi_array_ref<T, 9> > > > bisArray_t; > > bisArray_t _bisArray; > > ... > > > > and a class bisImage, which has a bisArray as well as a pointer to the > > data as read from file (1-dimensional structure): > > ... > > > > template<typename T> > > > > class bisImage: public bisObject { > > > > public: > > > > /** Constructor using existing array data > > Reformats array as bisImage > > */ > > bisImage ( T* _data, size_t _dimensions, std::vector<size_t> _sizes > > ): > > data(_data), dimensions(_dimensions) { > > > > This code (or You) comes from java or C#, doesn't it? ;-) In C++ it is > supposed to be this->[...] instead of this.[...] No, it's C (which doesn't use any of this -not properly at least). The whole this[...] business was not supposed to be there anyway I realised. The reason that I went to boost:: is that I was hoping to get one class for all data types (using T) and dimensionalities (using multi_array) > Second thing: the member storage is initialized with the default constructor > (which in this case does not exist => error ), and then assigned (below). > > I suggest a change to: > bisImage([...]) : [...], storage( _data, _dimensions, _size ) { [...] > and remove the assignment from the body of the constructor > > Note also: I have read in many places, that you should not use names > beginning with an underscore (_), because they are reserved for > compiler/library implementation. One of those places was Herb Sutter's gotw > series. Ah! The underscore names come from a library that I tried to imitate which has successfully incorporated some aspects of boost(it is called MIMAS). Have not reached the stage of 'nicifying' the code yet... I moved the storage thing to where you suggested (1 line up) and that does get rid of lots of errors. However what I am stuck with seems to be, in essence, still the same thing: >>> /home/amwink/programs/cpp/bis/src/bisniftiimage.cpp||In function ‘void bis::bisReadNifti(std::string)’:| >>> /home/amwink/programs/cpp/bis/src/bisniftiimage.cpp|102|warning: unused variable ‘testimage’| >>> /usr/include/boost/variant/variant.hpp||In constructor ‘boost::variant<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19>::variant() [with T0_ = boost::multi_array_ref<unsigned char, 1ul>, T1 = boost::multi_array_ref<unsigned char, 2ul>, T2 = boost::multi_array_ref<unsigned char, 3ul>, T3 = boost::multi_array_ref<unsigned char, 4ul>, T4 = boost::multi_array_ref<unsigned char, 5ul>, T5 = boost::multi_array_ref<unsigned char, 6ul>, T6 = boost::multi_array_ref<unsigned char, 7ul>, T7 = boost::multi_array_ref<unsigned char, 8ul>, T8 = boost::multi_array_ref<unsigned char, 9ul>, T9 = boost::detail::variant::void_, T10 = boost::detail::variant::void_, T11 = boost::detail::variant::void_, T12 = boost::detail::variant::void_, T13 = boost::detail::variant::void_, T14 = boost::detail::variant::void_, T15 = boost::detail::variant::void_, T16 = boost::detail::variant::void_, T17 = boost::detail::variant::void_, T18 = boost::detail::variant::void_, T19 = boost::detail::variant::void_]’:| >>> /home/amwink/programs/cpp/bis/src/bisarray.hpp|52|instantiated from ‘bis::bisArray<T>::bisArray(T*, size_t, std::vector<long unsigned int, std::allocator<long unsigned int> >) [with T = unsigned char]’| >>> /home/amwink/programs/cpp/bis/src/bisimage.hpp|33|instantiated from ‘bis::bisImage<T>::bisImage(T*, size_t, std::vector<long unsigned int, std::allocator<long unsigned int> >) [with T = unsigned char]’| >>> /home/amwink/programs/cpp/bis/src/bisniftiimage.cpp|126|instantiated from here| >>> /usr/include/boost/variant/variant.hpp|1198|error: no matching function for call to ‘boost::multi_array_ref<unsigned char, 1ul>::multi_array_ref()’| >>> /usr/include/boost/multi_array/multi_array_ref.hpp|623|note: candidates are: boost::multi_array_ref<T, NumDims>::multi_array_ref(T*, const typename boost::const_multi_array_ref<T, NumDims, T*>::storage_order_type&, const typename boost::const_multi_array_ref<T, NumDims, T*>::index*, const typename boost::const_multi_array_ref<T, NumDims, T*>::size_type*) [with T = unsigned char, long unsigned int NumDims = 1ul]| >>> /usr/include/boost/multi_array/multi_array_ref.hpp|469|note: boost::multi_array_ref<T, NumDims>::multi_array_ref(T*, const boost::detail::multi_array::extent_gen<NumDims>&, const boost::general_storage_order<NumDims>&) [with T = unsigned char, long unsigned int NumDims = 1ul]| >>> /usr/include/boost/multi_array/multi_array_ref.hpp|463|note: boost::multi_array_ref<T, NumDims>::multi_array_ref(T*, const boost::detail::multi_array::extent_gen<NumDims>&) [with T = unsigned char, long unsigned int NumDims = 1ul]| >>> /usr/include/boost/multi_array/multi_array_ref.hpp|417|note: boost::multi_array_ref<unsigned char, 1ul>::multi_array_ref(const boost::multi_array_ref<unsigned char, 1ul>&)| >>> ||=== Build finished: 1 errors, 1 warnings ===| So boost.variant now sugegsts that multi_array_ref() is called, a constructor with no arguments! I don't use that, and I don't even think it exists (because it produces a multi_array view of an *existing* C-style array! The only way I knew to initialise a bisArray was with using a switch statement -proper C: switch dims{ case 1: _bisarray=multi_array_ref<T,1> (data, sizes); break; case 2: _bisarray=multi_array_ref<T,2> (data, sizes); break; ... } That is the only way multi_array_ref is called! Any idea why a problem with the *default* constructor would turn up? Thanks for your suggestions! My error list already fits on one screen :) Alle Meije

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Simple serial port demonstration with boost asio asynchronous I/O
by Jeff Gray 25 Jan '11

25 Jan '11

A couple of weeks ago I posted a simple asynchronous demonstration of a telnet client using boost asio TCP network code. I have changed this code to turn it into a simple serial terminal application using the serial port support in the new version of boost asio. It required no changes at all the the read or write code. I just altered the initialization to use a serial port instead of a socket. Note that this is not intended to show how a fully functional application would work. There are plenty of areas that are not handled in this code. But it shows the idea and it's easy to build on this once you've got it working. Hope this helps someone else get started... Jeff

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[units] subtract_typeof_helper<> help!
by Terry Golubiewski 04 Jan '11

04 Jan '11

I'm trying to use boost::geometry and boost::units together. For some reason boost::geometry doesn't represent the difference of two points as vectors. So, I'm making my own Vector class and defining Vector = Point - Point. The sample program below doesn't compile because I need to tell the units library about the special properties of point subtraction (I think). terry #include <boost/geometry/geometry.hpp> #include <boost/units/systems/si.hpp> #include <boost/units/quantity.hpp> #include <boost/units/io.hpp> #include <iostream> #include <iomanip> using namespace std; using namespace boost; using namespace boost::geometry; using namespace boost::units; typedef point<double, 3, cs::cartesian> Point; class Vector { Point _impl; friend Vector operator-(const Point& lhs, const Point& rhs); explicit Vector(Point p) : _impl(p) { } public: Vector() : _impl(0) { } Vector(double dx, double dy, double dz=0) : _impl(dx, dy, dz) { } friend ostream& operator<<(ostream& os, const Vector& v) { return os << dsv(v._impl); } }; // Vector inline Vector operator-(const Point& lhs, const Point& rhs) { Point tmp(lhs); subtract_point(tmp, rhs); return Vector(tmp); } inline ostream& operator<<(ostream& os, const Point& pt) { return os << dsv(pt); } int main() { Point p1(1, 2, 3); Point p2(4, 5, 6); typedef quantity<si::length, Point> Position; typedef quantity<si::length, Vector> Displacement; Position start( p1 * si::meters); Position finish(p2 * si::meters); Displacement disp(finish - start); cout << "disp=" << disp << endl; return EXIT_SUCCESS; } // main

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[GIL] convert image view to const image view
by Curtis Gehman 21 Dec '10

21 Dec '10

I originally hoped that an actual function argument of type GIL mutable image view (e.g., gray8_view_t) would be automatically promoted to a (immutable or const) view (e.g., gray8c_view_t). But my experience (with version 1.44.0) indicates otherwise. It also seems like the const_view function, which generates a (const) view from an image is not overloaded to do the same using a mutable view. Obviously, I'm just getting starting using GIL, since this sort of conversion would, I presume, be used often. I've been searching the online documentation without success. Can someone point me to the answer for this basic task? In the meantime, I'll be reading the GIL header files. Thanks.

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[Interprocess] Strange behaviour on erase in a b::i::vector of b::i::weak_ptr
by Gaetan Gaumer 17 Dec '10

17 Dec '10

Hello Ion and others, I currently work with b::i::vectors storing b::i::managed_weak_ptr on objects created in a fixed_managed_shared_memory. I add shared_ptr whith push_back, but when I want to remove a weak_ptr using erase, the last item is erase instead of the one I want to remove. In the sample code below I add 3 objects and try to remove the middle one in both a vector of shared_ptr and a vector of weak_ptr : interprocessWeakVectorTest.cc http://pastebin.com/yDCngGw4 The result is the expected one for vector of shared_ptr, but not for a vector of weak_ptr : foo_shared_vector: 1 3 foo_weak_vector: 1 2 A tried the same with std::vectors of boost::shared_ptr and boost::weak_ptr (sample code below) : weakVectorTest.cc http://pastebin.com/fMEi0iaA The result is the expected one for both : foo_shared_vector: 1 3 foo_weak_vector: 1 3 I don't understand the behaviour of erase on b::i::vector of b::i::weak_ptr. Is this some kind of bug or am I doing something wrong ? For information I'm doing the same kind of thing with b::i::maps of b::i::shared_ptr and b::i::weak_ptr and the behaviour is correct. I compile this with : g++44 (GCC) 4.4.0 20090514 (Red Hat 4.4.0-6), and the 1.44 release of boost (but nothing in the 1.45 release note seems related to this), using options : -std=c++0x -lrt I don't know why but when I remove -std=c++0x this do not compile anymore even if I don't think I use any c++0x feature (am I ?). Can you check this or explain me my error ? Thank you. Gaëtan

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