June 2006 - Boost-users - lists.preview.boost.org

Design for boost::serialization of STL iterators.
by Carlo Wood 23 May '09

23 May '09

On Sat, Mar 11, 2006 at 11:45:36PM +0200, Peter Dimov wrote: > Carlo Wood wrote: > > > 1) WHY does boost::serialization not support serialization > > of iterators? > > It's very hard, if not impossible, in general. It is either impossible or possible. When it is possible, it can't be hard :p I think that at the moment of serialization, the actual container needs to be known. So, only concentrating on the syntax of the code that serializes an iterator, the following cannot work: ar & iter; However, the container will be known at that point (or at least, we might as well assume that). Therefore, I could imagine a syntax like: ar & foobar(container, iter); where 'foobar' is some template function (that will be part of boost::serialization in the future). Lets start with the last one (have to start somewhere). In order to deserialize the iterator (and taken into account that we already have the container) -- which makes me think that it might be better to pass a functor to operator& above. In other words, (at least for writing), use: template<class Container> struct Foobar { Foobar(Container const&, typename Container::const_iterator& iter) : M_container(container), M_iter(iter); private: Container const& M_container; Container::const_iterator& M_iter; }; and then assign to M_iter, whatever we find in M_container. > If you have access to the container to which the iterator i refers: > > a) if the container is a map, you can serialize i->first, then on > deserialization look up the key in the map using .find(); > > b) if the container is a sequence, and it has the same contents on > deserialization as it does on serialization, you can serialize the index of > the element - distance( c.begin(), i ). I don't think that it is a requirement that the whole container has to be read: either it's a map or set, in which case later insertions will not invalidate the container, or it is a vector, in which case we use an index, from which we can construct the end iterators before the whole container is reconstructed. Therefore, the following syntax can work imho: ar & FooBar(container, iter); Would you agree? There are a zillion questions and implementation details open - but I'd like to get anyones feedback about this type of interface for iterators before continuing. Current questions: What is a good name for Foobar? Am I right when I think that Foobar needs to be declared in boost::serialization? Now the hard part (for me) is that part that involves the internals of the boost library. At the moment one tries to serialize an iterator, it is possible (though not necessarily) that the object that the iterator points to is already serialized. In the case that we are dealing with an associative container (map or set etc), we don't want to store the contents of the object (or key part, in the case of a map) again: I'd like to just store that once, and store a reference in the archive at the other place. How can I make the library store an object only the first time and the store a reference the second time? This would be for an object of arbitrary type thus. I think that it is only feasible to do this when it's actually the same object (same memory address), which is the case; but while storing the object element of the container, the address of it isn't stored as well, is it? Is there a way to make: std::set<SomeData> s; [...] ar << s; Store the address of s (&s) along with the contents of s? And would that then automatically cause the library to not store that same object again when I do: std::set<SomeData>::iterator iter = s.find(...); [...] ar << *iter; Because then, &*iter would again be the same memory address as what was stored before. -- Carlo Wood <carlo(a)alinoe.com>

3 2

Boost Graph Library and Boehm Garbage Collector
by FBSL 08 Sep '08

08 Sep '08

Hello I am having trouble to garbage-collect adjacency_list<>. I have instanciated it with correctly garbage-collected vectors and lists (I have copied vecS and listS definitions, and added Boehm GC's default allocator so that they are garbage-collected). In my application I need to dynamically allocate many graphs, but it does not work, there is a (big) memory leak. Unfortunately, there is no template argument in adjacency_list<> to specify Boehm GC's allocator. Does anyone have a hint ? Snippet code "main.cpp" follows, compiled with Boost Graph Library 1.32, Boehm GC 6.4 and G++ 3.3.5, with command line : $ g++ -o main main.cpp -lgc -lgccpp -- #include <boost/graph/adjacency_list.hpp> #include <gc/gc_allocator.h> #include <gc/gc_cpp.h> #include <iostream> #include <vector> #include <list> using namespace std; using namespace boost; namespace boost { struct collected_vecS {}; struct collected_listS {}; template <class ValueType> struct container_gen<collected_vecS, ValueType> { typedef vector<ValueType,gc_allocator<ValueType> > type; }; template <class ValueType> struct container_gen<collected_listS, ValueType> { typedef list<ValueType,gc_allocator<ValueType> > type; }; template <> struct parallel_edge_traits<collected_vecS> { typedef allow_parallel_edge_tag type; }; template <> struct parallel_edge_traits<collected_listS> { typedef allow_parallel_edge_tag type; }; namespace detail { template <> struct is_random_access<collected_vecS> { enum { value = true }; typedef true_type type; }; } } typedef adjacency_list<collected_vecS, collected_vecS, directedS, no_property, no_property, no_property, collected_listS> graph; int main() { // leaks... while(true){ graph * g=new (UseGC) graph; for(unsigned int i=0; i<100; ++i){ add_vertex(*g); } for(unsigned int i=0; i<100; ++i){ for(unsigned int j=0; j<100; ++j){ add_edge(i,j,*g); } } } }

3 4

[statechart] history transitions make state-local-storage "un-cool"
by Mick Hollins 26 Jun '08

26 Jun '08

Apologies if this has been discussed before, but I couldn't find any mention of it: I am currently using the history facility of boost::fsm. I've discovered that when I re-enter a state, X, via a history transition I don't actually re-enter the same instance of X that I was in before, but instead enter a newly constructed instance of X. I just checked the UML spec regarding history transitions and it says that "Any necessary entry actions are performed", so given that boost::fsm uses constructors to represent entry actions I guess a new instance of X has to be constructed to ensure UML compliance. My actual concern is the effect this has on the "coolness" of state-local-storage (see http://boost-sandbox.sourceforge.net/libs/statechart/doc/faq.html#Whats_so_…) It seems to me that state-local-storage, which I agree is generally cool, is particularly un-cool (and bug-inducing) in the presence of history transitions. I'm not sure what a good alternative is, but just thought I'd raise the discussion. cheers, mick PS: does the history facility display the same semantics in boost::statechart? I plan to move to statechart real soon now ...

4 19

BGL: INTERNAL COMPILER ERROR in VC7.1
by Yariv Tal 10 Jun '07

10 Jun '07

This one was already posted by Nicholas Burlett awhile back (see http://lists.boost.org/MailArchives/boost-users/msg06534.php) but I have some new info that may help. The problem: ========= When compiling code that uses the boost.graph library the VC7.1 compiler shouts: c:\boost_1_32_0\boost\mpl\aux_\preprocessed\plain\apply_wrap.hpp(48) : fatal error C1001: INTERNAL COMPILER ERROR As Nicholas already noted, this seems to be due to some compiler problem with the boost.graph out_edge_iterators since it is caused by the following lines in my code: (FilteredGraphGenerator::FilteredGraph is a typedef of a boost::filtered_graph) typedef boost::graph_traits<FilteredGraphGenerator::FilteredGraph> ::out_edge_iterator oedge_iterator; oedge_iterator edgesItr, edgesEnd; boost::tie(edgesItr, edgesEnd) = boost::out_edges(itr->first, m_g.m_filteredGraph); while (edgesItr != edgesEnd) { // do anything! } In fact, it seems to be related to the operator!= between iterators (if the while loop is commented out it compiles). How ever, the error persists even after changing the operator!= to operator== : while (edgesItr == edgesEnd) { // do anything! } ========================================================================== Some findings: =========== * We used to use boost_1_30_0 and the code used to compile PERFECTLY. The problem only appeared after migrating to boost_1_32_0. * Calling directly to the "equal" function in iterator_core_access instead of the operator== works. typedef boost::graph_traits<FilteredGraphGenerator::FilteredGraph> ::out_edge_iterator oedge_iterator; oedge_iterator edgesItr, edgesEnd; boost::tie(edgesItr, edgesEnd) = boost::out_edges(itr->first,m_g.m_filteredGraph); while (boost::iterator_core_access::equal(edgesItr, edgesEnd, boost::mpl::true_())) { // do somthing } * The error message location is at the mpl::apply_wrap2 function. Any relation to the mpl::apply2 function used for declaring the operator== in the BOOST_ITERATOR_FACADE_INTEROP_HEAD macro? Have these functions changed since v1.30.0?

9 8

[Threads] Conditions and avoiding lengthy mutex locks (background loading for a game)
by Peter Mackay 11 Mar '07

11 Mar '07

Hello, I'm trying to use the Boost Threads library to help me implement a background loading system for a game I'm writing. I want to enqueue load requests while the main game thread is running, and have a separate thread load the data and pass back the appropriate objects. Currently when I enqueue a new request, I notify a 'something to do' condition, which my loading thread waits on. The trouble is, when I notify it, the loader could be loading in the background, and has a lock on the mutex connected with the condition. Would anyone be able to offer me any advice on how to solve this? Many thanks, Peter P.S. Please find attached my current implementation. begin 666 loader.cpp M(VEN8VQU9&4@(FQO861E<BYH<' B#0H-"B-I;F-L=61E(#QB;V]S="]B:6YD M+FAP<#X-"@T*;&]A9&5R.CIL;V%D97(H*0T*.B!T:')E861?<VAO=6QD7V5X M:70H9F%L<V4I#0I[#0H)=&AR96%D+G)E<V5T*&YE=R!B;V]S=#HZ=&AR96%D M*&)O;W-T.CIB:6YD*"9L;V%D97(Z.G1H<F5A9%]P<F]C+"!T:&ES*2DI.PT* M?0T*#0IL;V%D97(Z.GYL;V%D97(H*0T*>PT*"2\O(%-I9VYA;"!T:&4@=&AR M96%D('1O(&5X:70N#0H)>PT*"0EB;V]S=#HZ;75T97(a)Z.G-C;W!E9%]L;V-K M(&QO8VLH;75T97(a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` ` end begin 666 loader.hpp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`` ` end

4 6

How can we serialize pointer of type base abstract class pointing to Derived concrete class
by Piyush Kapadia 18 Jan '07

18 Jan '07

We have a situation where there is BaseAbstract class and Derived concrete class. Interface requires that we pass BaseAbstractClassPointer, using which user can provide any of Derived Concrete class pointer and Interface remain generic to them. However serializing BaseAbstractPointer is throwing following error - *A unregistered class* How do we handle this situation ? #include <iostream> #include <fstream> #include <boost/archive/text_iarchive.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/xml_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp> #include <boost/archive/binary_iarchive.hpp> #include <boost/archive/binary_oarchive.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/map.hpp> #include <vector> #include <map> #include <boost/archive/archive_exception.hpp> #include <boost/archive/basic_xml_archive.hpp> class BaseAbstract { public : virtual void setRate(double rate) = 0; virtual double getRate(int) = 0; }; class DerivedConcrete : public BaseAbstract { std::vector<double> rateVec; friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & BOOST_SERIALIZATION_NVP(rateVec); } public: DerivedConcrete(double rate) {rateVec.push_back(rate);} DerivedConcrete(){} virtual ~DerivedConcrete(){} void setRate(double rate){ rateVec.push_back(rate); }; double getRate(int idx){ return rateVec[idx]; }; }; class AnyClass { friend class boost::serialization::access; BaseAbstract* rate; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & BOOST_SERIALIZATION_NVP(rate); } public: AnyClass(BaseAbstract* rateInput){ rate = rateInput; }; AnyClass() {}; setRate(BaseAbstract* rateInput){ rate = rateInput; }; }; int main(int argc, char* argv[]) { try { DerivedConcrete* fr = new DerivedConcrete(12.12); fr->setRate(14.5); AnyClass ac; ac.setRate(fr); std::ofstream ofs("AC.xml"); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); oa << BOOST_SERIALIZATION_NVP(ac); ofs.close(); } catch (boost::archive::xml_archive_exception ex) { std::cerr << " X " << ex.what() << std::endl; } catch (boost::archive::archive_exception ex) { std::cerr << " A " << ex.what() << std::endl; } catch (std::exception ex) { std::cerr << " E " << ex.what() << std::endl; } catch (...) { std::cerr << "Unknown Exception " << std::endl; } return 0; }

3 4

Re: [Boost-users] Visual C++ 2005 help installing Boost
by Harry Georgakopoulos 17 Jan '07

17 Jan '07

I am having exactly the same problem as a previous user. Could you please show me how you fixed your boost build? I'm getting the following errors ...failed updating 120 targets ...skipped 80 targets... ...updated 847 targets... I don't know how to open the vsvars32.bat file in order to change the paths that Mr Kozicki suggested. Any help would be greatly appreciated. I have installed the latest SDK. Also, how do i get rid of the warnings? I know i need to define _SCL_SECURE_NO_DEPRECATE globally, but how do i do that exactly? Finally, how do i know i have a correct build install? How do i test it? Thank you Please send your response to hgeorgako(a)hotmail.com harry g.

5 5

vertex descriptors
by Luis Quesada 18 Dec '06

18 Dec '06

Dear all, Sorry for the newbie question! Given the index of a vertex, how can I get its descriptor? I guess function vertex (page 225 of The Boost Graph Library) does that but the function is not defined. In fact, what I want to do is to check whether an edge belongs to a graph in a context where descriptors get invalidated after vertex removals? Suppose I have done this: // create a typedef for the Graph type typedef adjacency_list<vecS, vecS, bidirectionalS> Graph; // Make convenient labels for the vertices enum { A, B, C, D, E, N }; const int num_vertices = N; const char* name = "ABCDE"; // writing out the edges in the graph typedef std::pair<int, int> Edge; Edge edge_array[] = { Edge(A,B), Edge(A,D), Edge(C,A), Edge(D,C), Edge(C,E), Edge(B,D), Edge(D,E) }; const int num_edges = sizeof(edge_array)/sizeof(edge_array[0]); // declare a graph object Graph g(num_vertices); Then I remove some vertices. Now I want to check whether edge <A,B> is still there. Calling edge(A,B,g) would not be OK because the descriptors are no longer referring to the same vertices.... Thanks in advance for your answer, Luis

6 15

[BGL] how to actually search with DFS/BFS?
by martin f krafft 22 Nov '06

22 Nov '06

This may seem like a silly question, but how does one actually search with DFS or BFS? Say I want to find the first node for which a predicate returns true in a BFS traversal starting at node N... The function signatures don't have a parameter for "criteria" or "predicate", so I guess it's up for a Visitor to implement such a check. What is not clear to me is how the visitor functions can break out of the search once a condition is true. Thanks, -- martin; (greetings from the heart of the sun.) \____ echo mailto: !#^."<*>"|tr "<*> mailto:" net@madduck invalid/expired pgp subkeys? use subkeys.pgp.net as keyserver! spamtraps: madduck.bogus(a)madduck.net "information superhighway" is just an anagram for "i'm on a huge wispy rhino fart".

9 12

Serialization problem on 64-bit Windows release
by Sigurd Saue 31 Oct '06

31 Oct '06

We've started to use boost serialization and I've run into problems with serialization of derived classes. The "funny" thing is that this happens only on 64-bit Windows release compiled with MS Visual 2005. The same code works fine on Linux 32/64 bit debug/release, on Windows 32-bit debug/release and on Windows 64-bit debug. But not Windows 64-bit release. We use boost version 1.33.1. Here's the code that causes problems (Parameter is the base class, ParamCollection is a vector of Parameters): template<class Archive> static void serialize(Archive & ar, ParamCollection & col, const unsigned int /*version*/) { ar.register_type(static_cast<FloatParameter*>(NULL)); ar.register_type(static_cast<IntParameter*>(NULL)); ar.register_type(static_cast<ChoiceParameter*>(NULL)); ar.register_type(static_cast<StringParameter*>(NULL)); ar.register_type(static_cast<BlobParameter*>(NULL)); ar & boost::serialization::base_object<std::vector<Parameter*> >(col); } When serializing the ParamCollection (serializing, not deserializing) an archive exception is thrown: unregistered class. I've tried to use both abstract and non-abstract base class without any success. I did some research in the boost code and found that the exception was thrown in polymorphic::save (oserializer.hpp) by the last condition (NULL == bpos_ptr). Any clues? Is there a workaround? Thanks, Sigurd

3 4

Converting epoch(long) to ptime in Boost.Date_Time
by gdprosch＠micron.com 23 Aug '06

23 Aug '06

I would like to convert epoch(long) time values to boost ptime and vice versa. On the surface this seems relatively easy but some of the functions needed are missing and there is an issue ensuring that the local time is properly applied. Has someone come up with an easy way to do this? I can convert to ptime like this... long epoch_in = 1140411002; // 2006-Feb-19 21:50:02 std::time_t stdtime ( epoch_in ); ptime = from_time_t( stdtime ); To convert from ptime back to epoch(long) there is no conversion provided the other way. I found some code the author supplied a few years ago here: http://lists.boost.org/MailArchives/boost-users/msg07254.php Unfortunately, the result does not correctly apply local time. The following code... std::time_t to_time_t(ptime t) { ptime start(gregorian::date(1970,1,1),time_duration(0,0,0)); return (t-start).total_seconds(); } ... produces a date with the value: 2006-Feb-20 04:50:02 and not 2006-Feb-19 21:50:02 (I am in US MST). I've played around with applying the local offset but I end up with a lot of lines of code that leave me wondering if there is a better way. It would be nice if it were simple like this (assuming local time adjustment is correctly applied)... long epoch_in = 1140411002; // 2006-Feb-19 21:50:02 ptime pt = from_epoch( epoch_in ); long epoch_out = to_epoch( pt ); Many thanks, > Greg Prosch > Micron Technology, Inc.

2 1

Building boost for 64-bit on AIX
by Patrik Jonsson 17 Aug '06

17 Aug '06

Hi, I'm trying to build boost (1.32.0) on an IBM SP2 under AIX5, using the 64-bit ABI. This is troublesome. I do: bjam "-sTOOLS=gcc" "-sGXX=g++ -maix64 -pthread" --prefix=$HOME --libdir=$HOME/lib64-gcc --includedir=$HOME/include-gcc install But it doesn't work. I get loads of errors like: gcc-Link-action bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/libboost_date_time-gcc-d-1_32.so ld: 0711-738 ERROR: Input file bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/greg_month.o: XCOFF32 object files are not allowed in 64-bit mode. collect2: ld returned 8 exit status set -e LIBPATH=bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true:$LIBPATH export LIBPATH "g++" -maix64 -pthread -g -fPIC -shared -o "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/libboost_date_time-gcc-d-1_32.so" "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/greg_month.o" "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/greg_weekday.o" "bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/date_generators.o" ...failed gcc-Link-action bin/boost/libs/date_time/build/libboost_date_time.so/gcc/debug/shared-linkable-true/libboost_date_time-gcc-d-1_32.so... ...skipped <@boost!lib64-gcc>libboost_date_time-gcc-d-1_32.so for lack of <@boost!libs!date_time!build/libboost_date_time.so/gcc/debug/shared-linkable-true>libboost_date_time-gcc-d-1_32.so... It seems it's using -maix64 ok when trying to build the library, but not when compiling... Can anyone tell me what the proper way of building boost under these conditions are? Thanks, /Patrik Jonsson

5 16

__fastcall warning when compiling boost in managed c++
by ChuMing 13 Jul '06

13 Jul '06

Hi, I am handling some project which mixes managed and unmanaged C++ code. With boost 1.33 I’m hitting problems with the header is_mem_fun_pointer_tester.hpp. There are warnings popping up due to the use of __fastcall calling convertion in boost and its incompatible with compiling some of our code with the /clr flag turned on. Managed C++ is incompatible with the __fastcall calling convention because what it does is it preloads certain registers with the function parameters but for /clr compilation it is compiling to MSIL so this cannot be done and upon encountering any __fastcall the Managed C++ compiler will change it to __stdcall. Does anyone know the implications of disabling these warnings and whether it is safe to do that? I did not get these warnings with the previous versions of boost though. Thanks and regards, Chu-Ming

2 3

Serialization of boost::any
by Sliwa, Przemyslaw (London) 11 Jul '06

11 Jul '06

Does it exist somewhere? Is it planned at all? Thanks for help Kind regards Pshemek Przemyslaw Sliwa Global Foreign Exchange FX Risk Engine Development Merrill Lynch ( +44 (0)20 7995 4182 ) +44 (0)79 6325 2319 * Email: przemyslaw_sliwa(a)ml.com -------------------------------------------------------- If you are not an intended recipient of this e-mail, please notify the sender, delete it and do not read, act upon, print, disclose, copy, retain or redistribute it. Click here for important additional terms relating to this e-mail. http://www.ml.com/email_terms/ --------------------------------------------------------

2 1

[boost.python] use of multi_array in python
by Sebastien Fortier 10 Jul '06

10 Jul '06

I'm having some problems with the use of multi_array's with python. What I'm trying to do is to export some functions that create multi_array's and pass these multi_array's to other functions that will extract other array's from them and display them. Lets say I have this as an example. //ArrayRef2D.h typedef for a 2D multi_array of doubles #ifndef ARRAYREF2D_H_ #define ARRAYREF2D_H_ #include <boost/multi_array.hpp> typedef boost::const_multi_array_ref < double, 2 > const_array_type2D_ref_d_t; typedef boost::multi_array < double, 2 > array_type2D_d_t; #endif /*ARRAYREF2D_H_*/ //Fstd.h 2D multi_array generator #ifndef FSTD_H_ #define FSTD_H_ #include "ArrayRef2D.h" #include <string> using namespace std; class Fstd { public: Fstd(string filename) : filename_(filename){} array_type2D_d_t get2Dfield() { array_type2D_d_t matrix(boost::extents[2][2]); matrix[0][0] = 0; matrix[0][1] = -1; matrix[1][0] = 20; matrix[1][1] = -30; return matrix; } private: string filename_; }; #endif /*FSTD_H_*/ //MatrixAlgorithm2D.h provides methods for displaying and manipulating matrices #ifndef MATRIXALGORITHM2D_H_ #define MATRIXALGORITHM2D_H_ #include "ArrayRef2D.h" #include <cassert> #include <cmath> #include <iostream> using namespace std; class MatrixAlgorithm2D { public: static array_type2D_d_t windChill(const_array_type2D_ref_d_t TT, const_array_type2D_ref_d_t UV) { assert((TT.shape()[0] == UV.shape()[0]) && (TT.shape()[1] == UV.shape()[1])); array_type2D_d_t RE(boost::extents[TT.shape()[0]][TT.shape()[1]]); for (unsigned int x = 0; x < TT.shape()[0]; x++) { for (unsigned int y = 0; y < TT.shape()[1]; y++) { if ((TT[x][y] <= 0.0) && (UV[x][y] >= 5.0)) { RE[x][y] = ( 13.1200 + 0.6215 * (TT[x][y]) + (0.3965 * (TT[x][y]) - 11.3700) * (pow((UV[x][y]),0.16))); } else { RE[x][y] = (TT[x][y]); } } } return RE; } static void display_d(const_array_type2D_ref_d_t a) { for (unsigned int x = 0; x < a.shape()[0]; x++) { for (unsigned int y = 0; y < a.shape()[1]; y++) { cout << a[x][y]; if(y < a.shape()[1] - 1) { cout << ", "; } } cout<<endl; } } }; #endif /*MATRIXALGORITHM2D_H_*/ //matrix.cpp boost.python interface file generated with pyste // Boost Includes ============================================================== #include "boost/python.hpp" #include "boost/cstdint.hpp" // Includes ==================================================================== #include "Fstd.h" #include "MatrixAlgorithm2D.h" // Using ======================================================================= using namespace boost::python; // Module ====================================================================== BOOST_PYTHON_MODULE(matrix) { class_< Fstd >("Fstd", init< const Fstd& >()) .def(init< std::string >()) .def("get2Dfield", &Fstd::get2Dfield) ; class_< MatrixAlgorithm2D >("MatrixAlgorithm2D", init< >()) .def(init< const MatrixAlgorithm2D& >()) .def("windChill", &MatrixAlgorithm2D::windChill) .def("display_d", &MatrixAlgorithm2D::display_d) .staticmethod("windChill") .staticmethod("display_d") ; } I generated my so file with bjam and then Python 2.3.5 (#2, Sep 4 2005, 22:01:42) [GCC 3.3.5 (Debian 1:3.3.5-13)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import matrix >>> dir(matrix) ['Fstd', 'MatrixAlgorithm2D', '__doc__', '__file__', '__name__'] >>> m = matrix.Fstd("HELLO") >>> l = m.get2Dfield() Traceback (most recent call last): File "<stdin>", line 1, in ? TypeError: No to_python (by-value) converter found for C++ type: boost::multi_array<double, 2, std::allocator<double> > So you see I can't use my code, what am I doing wrong? I would have liked to declare 2 arrays with get2Dfield() and pass these array to my windChill function to get another 2d matrix which I could then display with my display_d function. -- Sébastien Fortier

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[parameter] Interface questions
by Cromwell Enage 09 Jul '06

09 Jul '06

1. Will BOOST_PARAMETER_IMPL(name) expand to the name of the function that actually "owns" the main body of code? 2. Will there be a way to define a Boost.Parameterized member function outside the class definition? Or should we let the compiler decide whether or not to inline such a function? Cromwell D. Enage __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Re: [Boost-users] [boost] [Announce] Boost Installer for Visual C++ 7.1/8.0
by Trent Nelson 05 Jul '06

05 Jul '06

> Boost Consulting is pleased to announce the availability of a Windows > installer for the current Boost release (1.33.1). See: > > http://www.boost-consulting.com/download.html Any plans to make the .nsi file you're using public? There may be a few of us out there that have experience with Nullsoft and could contribute to the installer in some way, shape or form. Trent.

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[mpl] a few questions about set and map
by Yuval Ronen 05 Jul '06

05 Jul '06

I spent some time reading the mpl docs, and I have a few questions about mpl::set and mpl::map. 1. The docs assert there is a 'front' algorithm for set and map. This sounds weird to me, as the order of the types is them unspecified. But if I'm wrong, and 'front' is in place, then where is 'back'? 2. Where's multiset and multimap? In the boost/mpl directory I see something about multiset, but no real boost/mpl/multiset.hpp header, and there's absolutely nothing about multimap. 3. The docs say that the size of joint_view is the arithmetic sum of the sizes of the sequences of which it's composed. Is that true also in the case of set/map? For an mpl newbie it sounds reasonable that it will removed duplicates and might end up with a size that is smaller than the sum of its components. If it's not, then it sounds quite useless to use it for set/map. Thanks, Yuval

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error using lambdas: conversion from 'x' to non-scalar type 'y'
by klaus triendl 05 Jul '06

05 Jul '06

Hi, I'm rather new to lambdas. I wanted to use them to stream objects into a special stream (not a stl stream). the following code outlines the situation: ---- #include <iostream> #include <list> #include <algorithm> #include <boost/ref.hpp> #include <boost/shared_ptr.hpp> #include <boost/lambda/lambda.hpp> using namespace std; using namespace boost; using boost::lambda::_1; class MyStream { public: MyStream() {} }; class MySubStream: public MyStream { public: MySubStream(MyStream*) {} }; MyStream& operator <<(MyStream& os, const int&) { return os; } int main() { list<shared_ptr<int> > cont; MyStream osTop; MySubStream osSub(&osTop); for_each(cont.begin(), cont.end(), ref(osSub) << *_1); return 0; } ---- g++ outputs error: '/usr/include/boost/lambda/detail/operator_lambda_func_base.hpp:212: error: conversion from 'MyStream' to non-scalar type 'MySubStream' requested'. MS VC 2003.net says: boost\lambda\detail\operator_lambda_func_base.hpp(212) : error C2664: 'MySubStream::MySubStream(MyStream *)' : cannot convert parameter 1 from 'MyStream' to 'MyStream *'. The question is whether my code is correct at all and how I could use lambdas the right way. Thanks! Klaus Triendl

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When to use thread.join()
by Simon Reye 04 Jul '06

04 Jul '06

My apologies if this has been covered. I am new to boost and have been working with the boost thread class. I assume that the join() function waits for the thread to finish execution. But what if the thread has already finished executing? Can I still call join() and have it not wait for infinity? Simon

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[BGL] python bindings build graph from edge list
by John Reid 03 Jul '06

03 Jul '06

Hi, I was trying to build a graph from an edge list and ran into some problems. The following code throws an exception on write_graphviz(). I think it is because there's no property map called node_id in the graph. import boost.graph as bgl edges = [ ( 'a', 'b' ), ( 'b', 'c' ), ( 'c', 'a' ) ] g = bgl.Graph( edges ) g.write_graphviz( 'bind-copy.dot' ) I get the following: Traceback (most recent call last): File "<stdin>", line 1, in ? KeyError: 'node_id' I couldn't manage to generate the node_id property map automatically. So after you have built the graph with the edge list constructor how do you know which vertex is which? I ended up using the following code to create the graph: def build( edges ): # Create a graph to build g = bgl.Graph() # Construct some property maps node_ids = g.vertex_properties[ 'node_id' ] = g.vertex_property_map( 'string' ) color = g.vertex_properties[ 'color' ] = g.vertex_property_map( 'string' ) centrality = g.vertex_properties[ 'centrality' ] = g.vertex_property_map( 'float' ) weight = g.edge_properties[ 'weight' ] = g.edge_property_map( 'float' ) length = g.edge_properties[ 'len' ] = g.edge_property_map( 'float' ) # create the edges and vertices name_2_vertex = { } for ( name1, name2 ) in edges: if not name_2_vertex.has_key( name1 ): v1 = name_2_vertex[ name1 ] = g.add_vertex() node_ids[ v1 ] = name1 else: v1 = name_2_vertex[ name1 ] if not name_2_vertex.has_key( name2 ): v2 = name_2_vertex[ name2 ] = g.add_vertex() node_ids[ v2 ] = name2 else: v2 = name_2_vertex[ name2 ] e = g.add_edge( v1, v2 ) weight[ e ] = 0.1 length[ e ] = 4 # Color articulation points red for v in bgl.biconnected_components( g ): color[ v ] = 'red' # Assign centrality values to property map bgl.brandes_betweenness_centrality( g, centrality ) return g This code seems to works fine. So I thought I'd post this just to see if I was missing something obvious and/or in the hope someone else might find it useful. Best, John.

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boost 64bit support on windows x64 on amd64 hardware
by Chu-Ming Ng 03 Jul '06

03 Jul '06

Hi, I am porting some code that uses boost from 32-bit to the 64-bit platform and would like to know if the boost library supports this platforms. thanks! Chu-Ming

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Locking smart pointer
by Mattias Brändström 02 Jul '06

02 Jul '06

Hello! I have a small class to show you and perhaps get some comments on: <code> #include <boost/shared_ptr.hpp> #include <boost/thread.hpp> template <typename T> class LockPointer { public: class LockProxy { public: LockProxy(boost::shared_ptr<T> p, boost::shared_ptr<boost::recursive_mutex> mutex) : p_(p), lock_(new boost::recursive_mutex::scoped_lock(*mutex)) { } boost::shared_ptr<T> operator->() { return p_; } private: boost::shared_ptr<T> p_; boost::shared_ptr<boost::recursive_mutex::scoped_lock> lock_; }; LockPointer(boost::shared_ptr<T> o) : p_(o), mutex_(new boost::recursive_mutex()) { } LockProxy operator->() { return LockProxy(p_, mutex_); } private: boost::shared_ptr<T> p_; boost::shared_ptr<boost::recursive_mutex> mutex_; }; </code> The purpose of this class is to lock a mutex before each method call on an object of class T, and unlock the mutex when that call returns. It seems that this would be something that one would like to have in some cases. Maybe so many cases that it might be part of boost somewhere? I haven't found any library in boost that does this. Is there one? I haven't done anything like this before so it would be nice if anyone here could make some comments on the code. Will it do what I think it does or will it blow up in my face? :-) Regards, Mattias

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[serialization] Out of memory with Borland C++ Builder 60
by Federico Feller 02 Jul '06

02 Jul '06

Hi everyone. Im having problems compiling some code with Borland C++ Builder 6 that includes libboost serialization. In particular Im having troubles registrating a new class in order to be serialized. The new class, say A3, is a subclass of antother that is declared abstract, say A. A has already some subclases (A1, A2) that are serialized correctly. As I did for other subclasses on the same hierarchy, I added the instruction ar.register_type(static_cast<A3 *>(NULL)); in the load/save method of another class that serializes a pointer to the base class of the hierarchy. After doing that, I tried to compile the code and got the following error from the compiler: [C++ Fatal Error] if.hpp(72): F1008 Out of memory I really have no idea whats going on. Any ideas? Thanks Federico __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

4 7

Replacing C functions with boost::function for callback functions in OpenGL
by Stephen Torri 01 Jul '06

01 Jul '06

I have a main file from my OpenGL program which contains global variables and the functions that are used by OpenGL as callback functions. For example: int a; float b; void display () { .... display code calls ... } int main (int argc, char **argv) { glutDisplayFunc( display ); } Now I thought I would put all the variables and functions into a class and use that in the main. Here is where I am getting stuck on the use of boost::function. I changed the code to look something like the following: class MyMain { int a; float b; void display() { ... display code calls ... } } int main (int argc, char **argv) { MyMain m_ref; boost::function<void()> disp_func = boost::bind ( &MyMain::display, &m_ref ); glutDisplayFunc ( disp_func ); } What I am getting back from the g++ compiler is the following error message: error: cannot convert `boost::function<void ()(), std::allocator<void> >' to `void (*)()' for argument `1' to `void glutDisplayFunc(void (*)())' Any ideas where I am going wrong? Stephen

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