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

a question about asynchronous I/O
by 李慧霸 21 Apr '06

21 Apr '06

I'm trying to start network programming with boost::asio library, and I come across a question: if I have issued multiple async_read to the same one socket, will the OS execute these IO command out of order? My platform is WinXPSP2+VC2003. lihuiba 2006-04-21

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Re: [Boost-users] BGL: std::map<Edge, int> needs the < operator
by Ovanes Markarian 21 Apr '06

21 Apr '06

Another way would be to implement a global less than operator overload. You can also implement this operator within a class, so that std::less_than is able to call it. Here are some examples... //gloabl operator overlaod sample class Edge { friend bool operator < (const Edge&, const Edge&); public: //your implementation private: //data members }; inline bool operator < (const Edge& e1, const Edge& e2) { return (e1.prop1 < e2.prop1) && (e1.prop2 < e2.prop2) && ...; } //implementig the comaprison operator in the class // if you don't want this operator to be accessible from other classes, // declare the std::less_than<Edge> as friend and make this operator protected class Edge { friend class std::less_than<Edge>; protected: inline bool operator <(const Edge& e) { return (prop1 < e.prop1) && (prop2 < e.prop2) && ...; } //your class implementation }; I do not say that this implementation is better then the one suggested by Dmitry, I would only like to show up all possiblities. Dmitri's implementation is more flexible in regards of compile time type calculations or if you don't have the source code of Edge. My implementation does not involve additional overhead required to create a function object for comparison and delegate comparison through it. In this case the object is only 1 byte big, but if you add additional fields to it memory usage will grow with every comparison. With Kind Regards, Ovanes Markarian > On Fri, April 21, 2006 10:41, Dmitry Bufistov said: >> I'm using the following for a couple of monthes. Seems to work. >> ////////////////////////////////////////// >> struct edge_less_than >> : public std::binary_function<edge_descriptor_t, edge_descriptor_t, >> bool> >> { >> bool operator()(const edge_descriptor_t& __x, >> const edge_descriptor_t& __y) const >> { >> //return __x.second.get_property() < __y.second.get_property(); >> //return &__x < &__y; >> return __x.get_property() < __y.get_property(); >> } >> }; >> >> You can do something better depending of what you need. Possible this >> will help >> http://lists.boost.org/boost-users/2004/08/7579.php >> Regards, >> --dima >> Thomas Costa wrote: >>> write your own total ordering/comparison function object for Edge >>> objects and declare the map type using this function. >>> >>> On Apr 20, 2006, at 7:55 PM, Irek Szczesniak wrote: >>> >>> >> >> >> > > > With Kind Regards, Ovanes Markarian

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Re: [Boost-users] [Graph] bundled properties and connected_components
by Detlef Mages 21 Apr '06

21 Apr '06

Hi, What you are missing is a color map. One solution is to use bundled properties: #include <boost/config.hpp> #include <vector> #include <map> #include <iostream> // for std::cout #include <algorithm> // for std::for_each #include <boost/utility.hpp> // for boost::tie #include <boost/graph/graph_traits.hpp> // for boost::graph_traits #include <boost/graph/adjacency_list.hpp> #include <boost/graph/connected_components.hpp> using namespace boost; struct Node { int index; //****color property****************************** boost::default_color_type m_algo_color; //****color property****************************** }; struct Boundary { double something; }; typedef boost::adjacency_list< boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS> Graph; int main(int argc, char*argv[]) { Graph g(5); boost::graph_traits<Graph>::vertex_iterator vi, viend; std::vector< int > c( num_vertices(g) ); int num; // manually intialize the vertex index, // because we have listS as vertex list type int n = 0; for (tie(vi, viend) = vertices(g); vi != viend; ++vi, ++n) { g[*vi].index = n; } //****modified call****************************** num = connected_components(g, make_iterator_property_map(c.begin(), get(&Node::index, g)), boost::color_map( get(&Node::m_algo_color, g) )); //****modified call****************************** return 0; } Detlef

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[mpl] Please help with mpl::equal
by rincewind 21 Apr '06

21 Apr '06

Please tell me why the following fragment prints 0 - I thought it should print 1: typedef mpl::vector_c<int, 1, 2, 3> v1; typedef mpl::vector<mpl::int_<1>, mpl::int_<2>, mpl::int_<3> > v2; cout << mpl::equal<v1, v2>::value << "\n";

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[Graph] bundled properties and connected_components
by André Loose 21 Apr '06

21 Apr '06

Hi, I use an undirected graph with bundled properties and want to find out, whether it is connected, or not. Reading the documentation and some examples using property maps, I did not succeed in getting it to work. A minimal example that reproduces the compile errors follows. What am I doing wrong here: #include <boost/config.hpp> #include <vector> #include <iostream> // for std::cout #include <algorithm> // for std::for_each #include <boost/utility.hpp> // for boost::tie #include <boost/graph/graph_traits.hpp> // for boost::graph_traits #include <boost/graph/adjacency_list.hpp> #include <boost/graph/connected_components.hpp> using namespace boost; struct Node { int index; }; struct Boundary { double something; }; typedef boost::adjacency_list< boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS> Graph; int main(int argc, char*argv[]) { Graph g(5); boost::graph_traits<Graph>::vertex_iterator vi, viend; std::vector<int> c(num_vertices(g)); int num; // manually intialize the vertex index, // because we have listS as vertex list type int n = 0; for (tie(vi, viend) = vertices(g); vi != viend; ++vi, ++n) { g[*vi].index = n; } num = connected_components(g, make_iterator_property_map(c.begin(), get(&Node::index, g), c[0])); return 0; } compile log: Compiler: Default compiler Executing g++.exe... g++.exe "Y:\graph\boost\test2.cpp" -o "Y:\graph\boost\test2.exe" -I"C:\Dev-Cpp\lib\gcc\mingw32\3.4.2\include" -I"C:\Dev-Cpp\include\c++\3.4.2\backward" -I"C:\Dev-Cpp\include\c++\3.4.2\mingw32" -I"C:\Dev-Cpp\include\c++\3.4.2" -I"C:\Dev-Cpp\include" -L"C:\Dev-Cpp\lib" C:/Dev-Cpp/include/boost/property_map.hpp: In member function `R boost::iterator_property_map<RandomAccessIterator, IndexMap, T, R>::operator[](typename boost::property_traits<IndexMap>::key_type) const [with RandomAccessIterator = __gnu_cxx::__normal_iterator<boost::default_color_type*, std::vector<boost::default_color_type, std::allocator<boost::default_color_type> > >, IndexMap = boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t>, T = boost::default_color_type, R = boost::default_color_type&]': C:/Dev-Cpp/include/boost/property_map.hpp:319: instantiated from `void boost::put(const boost::put_get_helper<Reference, PropertyMap>&, K, const V&) [with PropertyMap = boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::default_color_type*, std::vector<boost::default_color_type, std::allocator<boost::default_color_type> > >, boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t>, boost::default_color_type, boost::default_color_type&>, Reference = boost::default_color_type&, K = void*, V = boost::default_color_type]' C:/Dev-Cpp/include/boost/graph/depth_first_search.hpp:197: instantiated from `void boost::depth_first_search(const VertexListGraph&, DFSVisitor, ColorMap, typename boost::graph_traits<G>::vertex_descriptor) [with VertexListGraph = boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, DFSVisitor = boost::detail::components_recorder<boost::iterator_property_map<__gnu_cxx::__normal_iterator<int*, std::vector<int, std::allocator<int> > >, boost::bundle_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, void*, Node, int>, int, int&> >, ColorMap = boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::default_color_type*, std::vector<boost::default_color_type, std::allocator<boost::default_color_type> > >, boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t>, boost::default_color_type, boost::default_color_type&>]' C:/Dev-Cpp/include/boost/graph/depth_first_search.hpp:246: instantiated from `static void boost::detail::dfs_dispatch<boost::detail::error_property_not_found>::apply(const VertexListGraph&, DFSVisitor, Vertex, const boost::bgl_named_params<P, T, R>&, boost::detail::error_property_not_found) [with VertexListGraph = boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, Vertex = void*, DFSVisitor = boost::detail::components_recorder<boost::iterator_property_map<__gnu_cxx::__normal_iterator<int*, std::vector<int, std::allocator<int> > >, boost::bundle_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, void*, Node, int>, int, int&> >, P = boost::detail::components_recorder<boost::iterator_property_map<__gnu_cxx::__normal_iterator<int*, std::vector<int, std::allocator<int> > >, boost::bundle_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, void*, Node, int>, int, int&> >, T = boost::graph_visitor_t, R = boost::no_property]' C:/Dev-Cpp/include/boost/graph/depth_first_search.hpp:324: instantiated from `void boost::depth_first_search(const VertexListGraph&, const boost::bgl_named_params<P, T, R>&) [with VertexListGraph = boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, P = boost::detail::components_recorder<boost::iterator_property_map<__gnu_cxx::__normal_iterator<int*, std::vector<int, std::allocator<int> > >, boost::bundle_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, void*, Node, int>, int, int&> >, T = boost::graph_visitor_t, R = boost::no_property]' C:/Dev-Cpp/include/boost/graph/connected_components.hpp:93: instantiated from `typename boost::property_traits<IndexMap>::value_type boost::connected_components(const Graph&, ComponentMap) [with Graph = Graph, ComponentMap = boost::iterator_property_map<__gnu_cxx::__normal_iterator<int*, std::vector<int, std::allocator<int> > >, boost::bundle_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, void*, Node, int>, int, int&>]' Y:\graph\boost\test2.cpp:38: instantiated from here C:/Dev-Cpp/include/boost/property_map.hpp:349: error: no match for 'operator+' in '((const boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::default_color_type*, std::vector<boost::default_color_type, std::allocator<boost::default_color_type> > >, boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t>, boost::default_color_type, boost::default_color_type&>*)this)->boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::default_color_type*, std::vector<boost::default_color_type, std::allocator<boost::default_color_type> > >, boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t>, boost::default_color_type, boost::default_color_type&>::iter + boost::get [with PropertyMap = boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t>, Reference = const boost::detail::error_property_not_found&, K = void*](((const boost::put_get_helper<const boost::detail::error_property_not_found&, boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t> >&)((const boost::put_get_helper<const boost::detail::error_property_not_found&, boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t> >*)(((const boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t>*)((const boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::default_color_type*, std::vector<boost::default_color_type, std::allocator<boost::default_color_type> > >, boost::adj_list_vertex_property_map<boost::adjacency_list<boost::setS, boost::listS, boost::undirectedS, Node, Boundary, boost::setS, boost::listS>, boost::detail::error_property_not_found, const boost::detail::error_property_not_found&, boost::vertex_index_t>, boost::default_color_type, boost::default_color_type&>*)this)) + 4u))), ((void* const&)((void* const*)(&v))))' C:/Dev-Cpp/include/c++/3.4.2/bits/stl_iterator.h:654: note: candidates are: __gnu_cxx::__normal_iterator<_Iterator, _Container> __gnu_cxx::__normal_iterator<_Iterator, _Container>::operator+(const typename std::iterator_traits<_Iterator>::difference_type&) const [with _Iterator = boost::default_color_type*, _Container = std::vector<boost::default_color_type, std::allocator<boost::default_color_type> >] C:/Dev-Cpp/include/c++/3.4.2/bits/stl_bvector.h:345: note: std::_Bit_const_iterator std::operator+(ptrdiff_t, const std::_Bit_const_iterator&) C:/Dev-Cpp/include/c++/3.4.2/bits/stl_bvector.h:261: note: std::_Bit_iterator std::operator+(ptrdiff_t, const std::_Bit_iterator&) Execution terminated

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Newbie: undefined symbol
by Olivier Destrebecq 20 Apr '06

20 Apr '06

I'm including the serialization library in the library I'm building. It compiles without errors but produces a lot of warning: serialization/base_object.hpp:136:57: warning: "__MWERKS__" is not defined serialization/base_object.hpp:147:60: warning: "__BORLANDC__" is not defined archive/basic_xml_iarchive.hpp:41:41: warning: "BOOST_MSVC" is not defined archive/basic_text_oprimitive.hpp:29:51: warning: "BOOST_DINKUMWARE_STDLIB" is not defined I'm building on a mac (10.4.6, intel), and the header file in which I'm including the serialization stuff looks like this: #include <string> #include <sstream> #include <boost/archive/tmpdir.hpp> #include <boost/archive/xml_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp> Any help appreciated Thanks, Olivier Destrebecq olivierd(a)real.com

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BGL: add_vertex deletes properties
by Fred Labrosse 20 Apr '06

20 Apr '06

All, I have: typedef boost::adjacency_list<boost::listS, boost::listS, boost::undirectedS, place, link> mapType; place* newPlace = new place("here-and-there"); mapType::vertex_descriptor newPlaceDesc = add_vertex(*newPlace, theMap); where the destructor of place is: place::~place() { // Just to make sure... std::cout << "Deleting place " << name << std::endl; // ... } When I run that, I do get: Deleting place here-and-there just after adding the vertex. In other words, a property is being deleted, probably a copy of the one I gave. I even tried (to make it explicitly like the documentation says): mapType::vertex_descriptor newPlaceDesc = add_vertex(static_cast<const place&>(*newPlace), theMap); and the same happens. Is that suppose to happen? Cheers, Fred

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[thread] Multiple readers, one writer locking
by Scott 20 Apr '06

20 Apr '06

I need to design a multiple reader, one writer type thread locking on a STL container. I've been using boost::threads for all my threading and locking so far, but I haven't found a way to do what I want. Then I saw this in the release notes: *************** Read/write mutex functionality added New classes, boost::read_write_mutex, boost::try_read_write_mutex, and boost::timed_read_write_mutex were added. Note Since the read/write mutex and related classes are new, both interface and implementation are liable to change in future releases of Boost.Threads. The lock concepts and lock promotion in particular are still under discussion and very likely to change. *************** But I can't find any documentation on it. Can someone help me out here? Thanks, Scott

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newbie question to Boost.Build linking to an external library jam
by wewolski 20 Apr '06

20 Apr '06

Hi, I am trying to compile the example from regex_token_iterator.html using the following entries in the Jamroot file. #Jamroot exe readdata : readdata.cpp : <include>/data/cpp/boost/include/boost-1_33_1/ ; install dist : readdata : <location>. ; and im getting a linker error (collect2: ld returned 1 exit status) However all my attempts to specify the external library location failed. For example I have tried to add lib boost_regex : : <file>boost_regex <search>/data/cpp/boost/lib/ ; exe regexexp : regexexp.cpp .//boost_regex ... and many more weird stuff without success. I found something in about site-config.jam in the manual but the example is not very clear to me. Can anyone please help? Eryk

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Class method cascade
by John Metta 20 Apr '06

20 Apr '06

Does Boost have any magic to help with a class method cascade? Consider: struct INFO { float mass; float volume; ... virtual void Reset() { mass = 0.0f; volume = 0.0f; ... }; } struct WATER_INFO : virtual INFO { float rateInfow; float rateOutflow; ... virtual void Reset() { rateInflow = 0.0f; rateOutflow = 0.0f; super.Reset(); // Wish to cascade a reset function down. }; }; struct SURFACE_WATER_INFO : virtual INFO { ... } // cascading to reset the variables at any level. Disclaimer: I recognize that this is a ... let's say "less than elegant" solution. Unfortunately, I've been given a 20,000 line monolithic implementation (there should be no fewer than 10 in here) of a jungle and am trying to put a bit of duct tape on some things in order to make it run to finish my thesis. Given time, I would re-write the entire thing correctly, but I don't have that luxury currently. Cheers, -j -- John Metta http://jmetta.com "A computer without windows is like a dog without bricks tied to its head."

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