December 2011 - Boost-users

Boost.Container string operator+ problem
by dave_chp 27 Dec '11

27 Dec '11

Using boost 1.48 and vs2010 gives me an error when trying to use boost::container::string. #include <boost/container/string.hpp> int main( int, char *[] ) { using boost::container::string; string hello = "hello "; string world = "world"; string hello_world = hello + world; } 1>d:\sdk\boost_1_48_0\boost\container\string.hpp(2368): error C2248: 'boost::container::containers_detail::basic_string_base ::alloc' : cannot access protected member declared in class 'boost::container::containers_detail::basic_string_base ' 1> with 1> [ 1> A=std::allocator<char> 1> ] 1> d:\sdk\boost_1_48_0\boost\container\string.hpp(214) : see declaration of 'boost::container::containers_detail::basic_string_base ::alloc' 1> with 1> [ 1> A=std::allocator<char> 1> ] 1> d:\tmp\xxx.cpp(15) : see reference to function template instantiation 'boost::container::basic_string<CharT,Traits,A> boost::container::operator +<char,std::char_traits<char>,std::allocator<_Ty>>(const boost::container::basic_string<CharT,Traits,A> &,const boost::container::basic_string<CharT,Traits,A> &)' being compiled 1> with 1> [ 1> CharT=char, 1> Traits=std::char_traits<char>, 1> A=std::allocator<char>, 1> _Ty=char 1> ] 1> d:\tmp\xxx.cpp(20) : see reference to function template instantiation 'void hello_world_test<boost::container::string>(void)' being compiled 1> template <class CharT, class Traits, class A> inline basic_string<CharT,Traits,A> operator+(const basic_string<CharT,Traits,A>& x, const basic_string<CharT,Traits,A>& y) { ... str_t result(reserve, x.size() + y.size(), x.alloc()); ... } should this maybe be x.get_allocator() instead of x.alloc()? -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-Container-string-operator-problem-… Sent from the Boost - Users mailing list archive at Nabble.com.

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[smart_ptr] Inclusion of unique_ptr
by Szymon Gatner 27 Dec '11

27 Dec '11

Hi, as suggested by Dave Abrahams I am now turning here with proposition of including unique_ptr<> to smart_ptr library. Newly accepted boost.move enables portable implementation and move-aware containers in boost.container allow to take full advantage of this now standard pointer type. Attaching proposed implementation. -- Szymon Gatner The Lordz Games Studio www.thelordzgamesstudio.com

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whitebox testing with boost unit test framework?
by Chris Cleeland 26 Dec '11

26 Dec '11

I'm using the boost unit test framework to implement unit tests for code. I'm wondering if there is a best-practice for doing white-box testing/internal state inspection of types under test. My hack right now is to strip out "protected" and "private" from the header, but I hold my nose as I do that. Thoughts/suggestions? -- Chris Cleeland

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A* heuristic
by giridhar 24 Dec '11

24 Dec '11

Hello All, I have a question about defining A* heuristic. I am trying to implement an algorithm in a paper using BGL. Here authors have used A* Dijkstra's to calculate shortest route with an additional constraint of route length should be no longer than a threshold value t. I think due to this threshold constraint they are using A* instead of normal Dijkstra's algorithm. I came to know A* is already there in Boost Graph Library. I just have a basic knowledge about A* algorithm that it finds the shortest route based on the heuristic H. I tried to look into the example in BGL, but I did not get any hint to define a heuristic. Can anybody give me some hints or some useful links of how can I define a heuristic for this particular scenario of finding the shortest path between nodes that is no longer than threshold t through A* Dijkstra. This would be really helpful for me to proceed further. -- Regards, Giridhar

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Problem with boost ::interprocess::string
by Josmon Paul 23 Dec '11

23 Dec '11

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filesystem::path threadsafe ?? (1.48)
by Aris Basic 22 Dec '11

22 Dec '11

is filesystem::path threadsafe ? i think im seeing issues related to conversion of std::string to std::wstring (that is being used by path on windows) (so thats put blame onto string to wstring conversion) did anyone see anything like that ? if not ill try to create a small sample app that recreates the issue. code portion <similar code run in multiple threads> std::string spath("c:\\somefolder"); fs::path path(spath); // i get crash within this call seems like conversion is using static instance of codecvt and it breaks on call in (do_in) maybe its just windows codecvt issue

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Using boost::uuids::uuid as a map index
by Tim Burgess 22 Dec '11

22 Dec '11

Hi, I'm new to using boost and have hit a problem using UUID. I have a set of classes that have UUID variables to provide unique identifiers. I wish to achieve two things: 1 - Allow objects to reference each other based on their UUID values (imagine the usual databasing student/teacher/course models); 2 - Maintain std::map collections of objects of the same class. Initially, I made the mistake of creating a class instance containing my UUID then inserting it into a map: Std::map <boost::uuid::uid, myClass> myMap; The index of the entry was set as follows: Std::pair <boost::uuids::uuid, myClass> myPair; myPair = std::make_pair( myClassInstance.UUIDField, myClassInstance); myMap.insert( myPair); All look-ups within the map based on the UUID then fail, as adding the object to the map is essentially a copy operation and UUID is non-copyable, so new unique identifiers were generated. I then tried: Std::map <boost::uuids::uuid *, myClass*> myMap; I thought that this should work as the actual UUID value would only ever be held in a single instance of myClass and the relationships between objects could be maintained by following the pointers. Unfortunately, look-ups using this scheme also fail and I can't see where I'm going wrong. Can anybody advise, please? Best wishes. Tim Burgess Raised Bar Ltd Phone: +44 (0)1827 719822 Don't forget to vote for improved access to music and music technology at http://www.raisedbar.net/petition.htm -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Cromwell Enage Sent: 10 December 2011 05:42 To: boost-users(a)lists.boost.org Subject: [Boost-users] [boost-users][container] associative placement insertion Hi, all! I'm wondering how placement insertion works for pair-associative Boost.Container types. For example, given: //[ex_code struct D { D(char,char) {} // Insert Boost.Move awareness here... }; boost::container::map<int,D> my_map; //] Will my_map.emplace(0, 't', 'p') call D('t', 'p') and move the object into the map? Will Boost.Unordered work the same way? TIA! Cromwell D. Enage _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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boost::polygon::polygon_set
by Egon Schaal 22 Dec '11

22 Dec '11

Hello I have a question to use the function template <typename T, typename coord_type> T& simplify(T& polygon_set, distance_type threshold) How must I define the parameter distance_type My typedefs are set to typedef boost::polygon::point_data<double> point; typedef boost::polygon::polygon_set_data<double> polygon_set; typedef boost::polygon::polygon_with_holes_data<double> polygonwh; typedef boost::polygon::polygon_data<double> polygon; I think the distance_type must be a double. Mit freundlichen Grüßen / Best regards Egon Schaal ///////////////////////////////////////////////// Egon Schaal CAD-Consulting, Softwareerstellung Aspacherstr. 15 71522 Backnang Email egon.schaal(a)cad-cons.net Web http://www.cad-cons.com Tel (+49)7191-84498 Fax (+49)7191-71410 SteuerNr: 51336/01006 /////////////////////////////////////////////////

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Please help me to choose a container
by Jayden Shui 21 Dec '11

21 Dec '11

Hi All, I have a number of named objects of type B whose name can be accessed by B::Name(). B is polymorphic. D1, D2 and so on are derived from B. I want to put them in a set or map-like container ordered by their names. They are referenced by other objects, such as of type C. If the objects in the container are changed by its type (from type D1 to D2) or value, their users can know it automatically, i.e. those information is shared among owners and users. To erase an object in the container, first we need to ensure it is not be used by other objects. Please help me on choose a proper container with smart pointers. I am struggling with it by trying multi-index-container, pointer container, standard container, and cannot find a good way. Thanks a lot ! ! Best regards, Jayden

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How to make multi_index_container work with std::unique_ptr?
by Jayden Shui 21 Dec '11

21 Dec '11

Hi All, If the elements of a multi_index_container are std::unique_ptr, it doesn't seem to work because the assignment operator of std::unique_ptr is private. Any way to let it work? If I change unique_ptr to shared_ptr, it works. But I need a good performance. Or is there anyway to work around to get pointer container performance with multi index power? Thanks a lot! Jayden

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