February 2011 - Boost-users - lists.preview.boost.org

Generating Multinomial Random Numbers
by Stephan Kitchovitch 10 Feb '11

10 Feb '11

Hello, I was looking through the Math/Statistical Distributions and Random boost libraries to see if they provide an efficient way to generate random numbers from the multinomial distribution. I have read that one way of achieving this is to generate from binomial distributions sequentially, although I am uncertain as to how efficient this approach would be. Are there any alternative efficient approaches I could use? Does boost provide any other libraries that may help with this? If anyone could recommend another reliable random number generator that does generate from a multinomial dist it would be great! Thanks in advance. Regards, Stephan

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[boost.any] Inline allocation of small objects in any.
by Adarsh Soodan 10 Feb '11

10 Feb '11

Hi, The frequent heap usage of boost::any was problematic to me for small object sizes. So I made a small tweak in boost::any which provides inline allocation of objects smaller than a certain template defined size. It practically eliminated the performance overhead of heap allocation and deallocation in my project while providing all benefits of boost::any. You can see the changed file at http://gitorious.org/athi/athi/blobs/master/core/any.hpp It is not cleaned up, but I thought it worthwhile to have any comments from somebody who solved the same problem. Thanks, Adarsh

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[Serialization] Registering containers of user-provided types
by Vivek 10 Feb '11

10 Feb '11

I am writing a library that will handle storing and serializing user-defined types. The user-defined types are required to be themselves serializable. However the library uses templates to create containers of user types. These containers are then serialized through a base class pointer. I don't know how to export the container types to boost::serialization through the templates. The only way I can do it is to force the user of the library to BOOST_CLASS_EXPORT_GUID() every container type. I've tried unpacking the macro by looking at boost/serialization/export.hpp, but it is slightly complex... Is there a way to export a class as part of the template instantiation? Or another way to write the library to easily serialize containers of user-defined types? Thanks -v Example code: #include <iostream> #include <vector> #include <boost/foreach.hpp> #include <boost/serialization/access.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/base_object.hpp> #include <boost/serialization/export.hpp> #include <boost/archive/text_oarchive.hpp> ////////////////////////////////////////////////////////////////////////////// // Example code that would reside in the library ////////////////////////////////////////////////////////////////////////////// struct type_container_base { private: virtual void make_abstract() const {} friend class ::boost::serialization::access; template <typename ARCHIVE> void serialize(ARCHIVE &, const unsigned int) {} }; BOOST_SERIALIZATION_ASSUME_ABSTRACT(type_container_base) template <typename USER_TYPE> struct type_container : type_container_base { void add(const USER_TYPE& d) { _vector.push_back(d); } private: std::vector<USER_TYPE> _vector; friend class ::boost::serialization::access; template <typename ARCHIVE> void serialize(ARCHIVE & ar, const unsigned int) { ar & ::boost::serialization::base_object<type_container_base>(*this); ar & _vector; } }; ////////////////////////////////////////////////////////////////////////////// // Example user code that would use the library ////////////////////////////////////////////////////////////////////////////// struct user_type { user_type(int i) : _val(i) {} private: int _val; friend class ::boost::serialization::access; template <typename ARCHIVE> void serialize(ARCHIVE & ar, const unsigned int) { ar & _val; } }; // *** Is there a better way than forcing the user to do this for every // *** user_type they want to use with the library? BOOST_CLASS_EXPORT_GUID(type_container<user_type>, "type_container<user_type>") int main() { std::vector<type_container_base*> containers; type_container<user_type>* tc = new type_container<user_type>(); tc->add(user_type(7)); tc->add(user_type(42)); tc->add(user_type(1776)); containers.push_back(tc); { boost::archive::text_oarchive ar(std::cout); const std::size_t size = containers.size(); ar << size; BOOST_FOREACH(type_container_base* p, containers) ar << p; } return 0; }

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TTI library updated in the sandbox to version 1.2
by Edward Diener 10 Feb '11

10 Feb '11

I have updated the TTI library in the sandbox 'tti' directory to version 1.2. The TTI library, which is an abbreviation for the 'Type Traits Introspection' library, allows a programmer to introspect at compile time the inner elements of a C++ type. The introspection process depends on specifying the name of the inner element by different macros for different types of elements, and then using a generated metafunction to determine whether that element exists within the enclosing type. The inner elements which can be introspected are type, class template, member data, member function, static member data, and static member function. The main feature of the update is a set of macros generating metafunction classes for passing the metafunctions of the library as metadata. The documentation has also been updated and the code implementation has been made easier to follow. The TTI library is based on the type_traits_ext portion of the Concept Traits Library, with improvements and additions, and also reproduces functionality ( without changing existing code ), for the purposes of completeness, from Boost.MPL regarding introspection of types and templates. The purpose of the library is to provide a consistent set of interfaces for doing compile-time introspection of a type, which other template metaprogrammers can use in their code. If you are at all interested in compile-time introspection of types, please take a look at the functionality of this library. There is a readme.txt in the top-level sandbox tti directory, for anyone browsing the sandbox for interesting libraries, which basically replicates what is written here. There is a build.txt file in the doc subdirectory for building the documentation and running the tests. The documentation is also included as part of the sandbox files for those who can not build the docs. The library has been tested and works with gcc 3.4.2, 3.4.5, 4.3.0, 4.4.0, 4.5.0-1, 4.5.2-1 and VC++ 8.0, 9.0, 10.0. It may also work with other compilers. Questions, comments, suggestions, and bug reports are all welcome.

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[DateTime] convert to timeval
by John Rocha 09 Feb '11

09 Feb '11

Is there a method from the boost date time library to convert a ptime to a timeval? I see a method for converting to a struct tm, but not the other common basic time types. Thanks in advance, -=John

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graph
by Soso F 09 Feb '11

09 Feb '11

Hello, I'm using BGL to build a graph which represents a network. I'm wondering if I can read a file to be the input " vertices , edges and weight" without using graphviz. Thx

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why is make_shared using so much of my stack....?
by Michael Xu 09 Feb '11

09 Feb '11

Hi everyone, I've been investigating our program's memory usage, and one of the spots that I keep seeing the stack hitting its limit is when using boost::make_shared. I've written a simple test program, that completes fine when I use new... but fails with a stack overflow when I use boost::make_shared ======================== #include <iostream> #include <boost/shared_ptr.hpp> #include <boost/make_shared.hpp> using namespace std; struct arr { char arg[1024*1024]; }; struct test { struct arr array[1024]; }; int main() { test * myTest = new test(); //complete! if (!myTest) cout << "new alloc failed"; boost::shared_ptr<test> testPtr = boost::make_shared<test>(); //fails with stack overflow! if (!testPtr) { cout << "alloc failed;"; } } =========================== If you run this with a reasonable thread stack of 8 megabytes, it fails when using boost::make_shared. Here is the stack trace..... #0 boost::shared_ptr<test>::shared_ptr<test, boost::detail::sp_ms_deleter<test> >(test*, boost::detail::sp_ms_deleter<test>) () #1 boost::shared_ptr<test> boost::make_shared<test>() () #2 main () Is there a reason this happens? Thanks michael

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[intrusive] insert_check and insert_commit
by Paul Rose 09 Feb '11

09 Feb '11

Hi, I have a question regarding insert_check and insert_commit on an intrusive set. I know that you must call insert_commit after calling insert_check, with no modifications to the set between the two calls. Is it OK, however, to call insert_check and then never call insert_commit (even though insert_check was successful)? Say I have objects contained in multiple sets (using multiple hooks). I want to insert a new object into each of the sets, but only if I know that the insert will succeed on all of the sets. I call insert_check on each, and if all succeed I call insert_commit on each. If any of the insert_check calls fail, I do none of the insert_commits (even though all but one might have worked) It seems like it should be OK, and the documentation doesn't say that it won't work. I'm only concerned for two related reasons: 1) insert_check is not declared const. Does this mean that the set is already partially modified? 2) insert_commit is documented as constant time. Does this mean that any red-black rebalancing was already done during insert_check? If so, what happens if I never do the insert_commit? Thanks! Paul Rose

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[Function] "constness" lost on Function Signature
by nicolas david 09 Feb '11

09 Feb '11

Hi, I am using boost::function and have some issues on using it with visual studio 2005. If I declare a boost::function with some "const" argument this "constness" seems to be lost on boost function siganture. Then, future assigment to this function whith correct "const" argument lead to wrong matching. See code snipset below. This work fine under gcc 4.4 and visual 2010. ---------------------------------------------------------------------------------- #include <iostream> #include <vector> #include <boost/function.hpp> using namespace std; using namespace boost; class container_test { public: typedef boost::function<bool(const int,float,float)> FunctionType; bool static defaultFunctor(const int, float, float) { return true; } //void apply_functor( const FunctionType IsInside = defaultFunctor){} }; int main() { container_test my_container; container_test::FunctionType my_f; my_f = container_test::defaultFunctor; //my_container.apply_functor(); return 0; } ---------------------------------------------------------------------------------- error send by visual 2005 compiler with "const". If change "const int" to "int" it works. ( sorry for the "french") ---------------------------------------------------------------------------------- >main.cpp 1>..\main.cpp(22) : error C2679: '=' binaire : aucun opérateur trouvé qui accepte un opérande de partie droite de type 'bool (__cdecl *)(const int,float,float)' (ou il n'existe pas de conversion acceptable) 1> C:\Documents and Settings\dfc\Bureau\boost_1_44\boost/function/function_template.hpp(1103): peut être 'boost::function<Signature> &boost::function<Signature>::operator =<bool(__cdecl *)(int,float,float)>(Functor)' 1> with 1> [ 1> Signature=bool (int,float,float), 1> Functor=bool (__cdecl *)(int,float,float) 1> ] 1> C:\Documents and Settings\dfc\Bureau\boost_1_44\boost/function/function_template.hpp(1088): ou 'boost::function<Signature> &boost::function<Signature>::operator =(const boost::function<Signature> &)' 1> with 1> [ 1> Signature=bool (int,float,float) 1> ] 1> C:\Documents and Settings\dfc\Bureau\boost_1_44\boost/function/function_template.hpp(1110): ou 'boost::function<Signature> &boost::function<Signature>::operator =(boost::function<Signature>::clear_type *)' 1> with 1> [ 1> Signature=bool (int,float,float) 1> ] 1> C:\Documents and Settings\dfc\Bureau\boost_1_44\boost/function/function_template.hpp(1117): ou 'boost::function<Signature> &boost::function<Signature>::operator =(const boost::function3<R,T0,T1,T2> &)' 1> with 1> [ 1> Signature=bool (int,float,float), 1> R=bool, 1> T0=int, 1> T1=float, 1> T2=float 1> ] 1> lors de la tentative de mise en correspondance de la liste des arguments '(container_test::FunctionType, bool (__cdecl *)(const int,float,float))' ---------------------------------------------------------------------------------- Nicolas David

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Build bimap with iterators ... + lower_bound(..) ?
by Rytuto 09 Feb '11

09 Feb '11

Hello everyone, I have just started to use boost via boost::bimap. I have a problem when using iterators to build a new bimap. Here is a sample of my code : class MyObject {...Definitions of MyObject...}; struct Position{}; // Wherever you meet Pos, it will mean Position // Define my bimap type : typedef boost::bimap< set_of<tagged<double,Position> >, multiset_of<tagged< MyObject*, MyObject> > // because at one position, I can have many objects .... is that right ? > PosMap; typedef PosMap::value_type MyObjectPos; PosMap posX ; // This posX maps the position of my objects for(MyObject::iterator it = MyObject.begin() ; it!= = MyObject.end() ; it++) { // it is an iterator on MyObjects Vector3D position = it->GetPosition() ; // Fill my map : posX.insert(MyObjectPos(position.x(), (*it))); } // Now I would like just to select a window on my posX bimap: double x = something ; double R = something else ; // PosMap::left_iterator tmp_itLowX = posX.left.lower_bound(x-R); // PosMap::left_iterator tmp_itUpX = posX.left.lower_bound(x+R); // Here is my problem : PosMap m(posX.left.lower_bound(x-R), posX.left.lower_bound(x+R)); What is wrong with this piece of code ... ? //___________________________________________________________ Here is the output from the compiler : ./boost/bimap/container_adaptor/ordered_associative_container_adaptor.hpp: In member function ‘typename boost::bimaps::container_adaptor::ordered_associative_container_adaptor_base<Base, Iterator, ConstIterator, ReverseIterator, ConstReverseIterator, KeyType, IteratorToBaseConverter, IteratorFromBaseConverter, ReverseIteratorFromBaseConverter, ValueToBaseConverter, ValueFromBaseConverter, KeyToBaseConverter, FunctorsFromDerivedClasses>::type::iterator boost::bimaps::container_adaptor::ordered_associative_container_adaptor<Base, Iterator, ConstIterator, ReverseIterator, ConstReverseIterator, KeyType, IteratorToBaseConverter, IteratorFromBaseConverter, ReverseIteratorFromBaseConverter, ValueToBaseConverter, ValueFromBaseConverter, KeyToBaseConverter, FunctorsFromDerivedClasses>::lower_bound(const CompatibleKey&) [with CompatibleKey = double, Base = boost::multi_index::detail::ordered_index<boost::multi_index::member<boost::bimaps::relation::detail::relation_storage<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, true>, double, &boost::bimaps::relation::detail::relation_storage<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, true>::left>, std::less<double>, boost::multi_index::detail::nth_layer<2, boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, boost::bimaps::detail::bimap_core<boost::bimaps::set_of<boost::bimaps::tags::tagged<double, Position>, std::less<double> >, boost::bimaps::multiset_of<boost::bimaps::tags::tagged<MyObject*, MyObject>, std::less<MyObject*> >, mpl_::na, mpl_::na, mpl_::na>::core_indices, std::allocator<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true> > >, boost::mpl::v_item<Position, boost::mpl::vector0<mpl_::na>, 0>, boost::multi_index::detail::ordered_unique_tag>, Iterator = boost::bimaps::detail::set_view_iterator<boost::multi_index::detail::bidir_node_iterator<boost::multi_index::detail::ordered_index_node<boost::multi_index::detail::index_node_base<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, std::allocator<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true> > > > > >, ConstIterator = boost::bimaps::detail::const_set_view_iterator<boost::multi_index::detail::bidir_node_iterator<boost::multi_index::detail::ordered_index_node<boost::multi_index::detail::index_node_base<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, std::allocator<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true> > > > > >, ReverseIterator = boost::bimaps::detail::set_view_iterator<boost::reverse_iterator<boost::multi_index::detail::bidir_node_iterator<boost::multi_index::detail::ordered_index_node<boost::multi_index::detail::index_node_base<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, std::allocator<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true> > > > > > >, ConstReverseIterator = boost::bimaps::detail::const_set_view_iterator<boost::reverse_iterator<boost::multi_index::detail::bidir_node_iterator<boost::multi_index::detail::ordered_index_node<boost::multi_index::detail::index_node_base<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, std::allocator<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true> > > > > > >, KeyType = boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, false>, IteratorToBaseConverter = boost::bimaps::container_adaptor::support::iterator_facade_to_base<boost::bimaps::detail::set_view_iterator<boost::multi_index::detail::bidir_node_iterator<boost::multi_index::detail::ordered_index_node<boost::multi_index::detail::index_node_base<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, std::allocator<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true> > > > > >, boost::bimaps::detail::const_set_view_iterator<boost::multi_index::detail::bidir_node_iterator<boost::multi_index::detail::ordered_index_node<boost::multi_index::detail::index_node_base<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, std::allocator<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true> > > > > > >, IteratorFromBaseConverter = mpl_::na, ReverseIteratorFromBaseConverter = mpl_::na, ValueToBaseConverter = boost::bimaps::relation::detail::get_mutable_relation_functor<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true> >, ValueFromBaseConverter = boost::bimaps::relation::support::get_above_view_functor<boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true> >, KeyToBaseConverter = boost::bimaps::detail::set_view_key_to_base<double, boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, boost::multi_index::member<boost::bimaps::relation::detail::relation_storage<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, true>, double, &boost::bimaps::relation::detail::relation_storage<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, true>::left> >, FunctorsFromDerivedClasses = boost::mpl::vector<mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>]’: include/MyObjectManager.icc:184: instantiated from ‘std::vector<MyObject*, std::allocator<MyObject*> > MyObjectManager<T>::FindClosestITsWithinGivenRange(const ThreeVector&, double) [with T = Object]’ kit.cc:240: instantiated from here ./boost/bimap/container_adaptor/ordered_associative_container_adaptor.hpp:257: erreur: no match for call to ‘(boost::bimaps::detail::set_view_key_to_base<double, boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, boost::multi_index::member<boost::bimaps::relation::detail::relation_storage<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, true>, double, &boost::bimaps::relation::detail::relation_storage<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, true>::left> >) (const double&)’ ./boost/bimap/detail/set_view_base.hpp:38: note: candidats sont: const Key boost::bimaps::detail::set_view_key_to_base<Key, Value, KeyToBase>::operator()(const Value&) const [with Key = double, Value = boost::bimaps::relation::mutant_relation<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, mpl_::na, true>, KeyToBase = boost::multi_index::member<boost::bimaps::relation::detail::relation_storage<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, true>, double, &boost::bimaps::relation::detail::relation_storage<boost::bimaps::tags::tagged<const double, Position>, boost::bimaps::tags::tagged<MyObject* const, MyObject>, true>::left>] //___________________________________________________________ Thank you very much for your help and guidance, Mathieu

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