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[serialization] link error and exception on get_key
by Daniel Roberts 16 Jan '09

16 Jan '09

I have a derived class that exports its type and overrides get_key for serialization through a base class pointer. If I move the definition of the overridden get_key function out of the header into a cpp file, an assertion fails on line 49 of extended_type_info.cpp. If I define any other functions in the cpp file, I get a linker error saying that the get_key symbol is already defined. It looks to me that any serializable derived class must be completely defined in the header file. Is this correct? If so, why does such a limitation exist? Thank you

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[Graph] - Do bundled properties break the named parameters paradigm?
by David Conner 16 Jan '09

16 Jan '09

I was trying to work with astar-cities.cpp example and convert to using bundled property maps for the edge properties. This caused numerous issues (see yesterdays post for one example). I found that if I bypass the named parameters and make an explicit call to astar_search( ) then it works OK. Does anyone know if the bundle property maps causes general issues with named parameters? thanks, David --- More info ----------------------------------- Normally, the named parameters would created the property maps that are needed; e.g. thru the use of choose_param(cost, make_iterator_property_map (cost_map.begin(), index_map, cost_map[0])), This appears to break if I use a bundled parameter because of some issues with the limit templates among other things. If I explicitly create all of the parameters, things work fine. e.g. boost::astar_search (g, start, distance_heuristic<mygraph_t, cost, location*>(locations, goal), astar_goal_visitor<vertex>(goal), // Only the first of named parameters needs boost:: &pred_map[0] ,//boost::predecessor_map( ), &cost_map[0] ,//boost::rank_map( ), &dist_map[0] ,//boost::distance_map( ), weightmap,//boost::weight_map( ), =========<<<<< This was the bundled property &index_map[0],//boost::vertex_index_map( ),//IndexMap, &clr_map[0] ,//boost::color_map( ) , std::less<cost>(), boost::closed_plus<cost>(), std::numeric_limits<cost>::max BOOST_PREVENT_MACRO_SUBSTITUTION (), std::numeric_limits<cost>::min() );//.

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Boost:multi-index Question on usage of project & modify_key
by Ramesh 16 Jan '09

16 Jan '09

Hello. I am using projection technique & modify_key in one of my member functions: Assuming I have the following data in the container: ObjId ObjIp ObjIndex pMyObj ------------------------------------------------------------------------------------- ID1 10.10.1.2 1 0x10239032 ID2 10.10.1.3 2 0x23423423 ID3 10.10.1.4 3 0x23132423 The member function 'UpdateKeyObjId' accepts the value on column 3 as key & changes the corresponding value for the field in Column 1. My code seems to work fine for all rows except the last row. When I use modify key on the last record, the app crashes at the highlighted line. I am not sure if my usage of project & modify_key right, could someone please point out if there are any errors in the usage? Thanks /R struct MyMap { std::string ObjId; unsigned long ObjIp; unsigned long ObjIndex; MyObj *pMyObj; MyMap(std::string param_ObjId, unsigned long param_ObjIp, unsigned long param_ObjIndex, MyObj* param_pMyObj): ObjId(param_ObjId), ObjIp(param_ObjIp), ObjIndex(param_ObjIndex), pMyObj(param_pMyObj) {} ~MyMap(){ ObjId.erase(); ObjIp = 0; ObjIndex = 0; pMyObj = 0; } }; struct ObjId{}; struct ObjIp{}; struct ObjIndex{}; typedef multi_index_container< MyMap, indexed_by< ordered_unique< tag <ObjId>, BOOST_MULTI_INDEX_MEMBER(MyMap,std::string,ObjId)>, ordered_non_unique< tag<ObjIp>,BOOST_MULTI_INDEX_MEMBER(MyMap,unsigned long,ObjIp)>, ordered_unique< tag<ObjIndex>,BOOST_MULTI_INDEX_MEMBER(MyMap,unsigned long,ObjIndex)> > > tMyObjMap; class MyObjContainer{ private: tMyObjMap MyContainer; public: UpdateKeyObjId(unsigned long, std::string); }; bool MyObjContainer::UpdateKeyObjId(unsigned long param_ObjIndex, std::string param_ObjId) { typedef tMyObjMap::index<ObjIndex>::type tMyObjMapByIndex; tMyObjMapByIndex& ObjIndex_index = MyContainer.get<ObjIndex>(); tMyObjMap::index_iterator<ObjIndex>::type it = ObjIndex_index.find(param_ObjIndex); typedef tMyObjMap::index<ObjId>::type tMyObjMapById; tMyObjMapById::iterator ObjIdit = MyContainer.project<0>(it); // Use the modify_key method to update the ObjIp key with new value return MyContainer.get<0>().modify_key(ObjIdit, ll::_1 = param_ObjId); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }

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[graph] Modifying properties in a visitor?
by James C. Sutherland 15 Jan '09

15 Jan '09

Can a visitor modify properties in a graph? I would like to use the following visitor with the breadth_first_search algorithm: struct ExecPriorityVisitor : public boost::default_dfs_visitor { ExecPriorityVisitor(); void start_vertex( Vertex v, Graph& g ){ g[v].priority = 0; } void examine_edge( Edge e, Graph& g ){ const Vertex src = boost::source(e,g); Vertex dest = boost::target(e,g); int& priority = g[dest].priority; priority = std::max( priority, g[src].priority + 1 ); } }; However, it fails to compile because apparently the graph argument must be const. That implies that I cannot modify graph properties from within the visitor? Why not? Is the suggested approach to record the modifications in yet another object and later impose that on the graph, or is there a way to accomplish this through a visitor? James

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program_options.hpp issue
by S Josh 15 Jan '09

15 Jan '09

I am having compilation problem with program_options.hpp. I believe fix is simple. Current code: #if _MSC_VER > 1200 Proposed code: #if defined(_MSC_VER) && (_MSC_VER>1200) How dO I get this change incorporated into the boost source code? regards, Sandeep

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Re: [Boost-users] large enum and native array indexing
by Hicham Mouline 15 Jan '09

15 Jan '09

>I would say that the easiest way is to use the preprocessor. >#define BOOST_PP_LOCAL_MACRO(n) template<> struct >Position<BOOST_PP_CAT(OP, n)> { static const size_t value = n - 1; }; >#define BOOST_PP_LOCAL_LIMITS (1, MAX_OP) >#include BOOST_PP_LOCAL_ITERATE() >In Christ, >Steven Watanabe I think I wasn't clear enough: the 3rd party lib (which I can't change of course) provides, enum Op { OPone = 7, OPtwo = 9, OPthree = 45, OPfour = 7667 // there is no pattern in the names nor the numbers. }; // in fact, there are a hundred entries and I wished to generate from Op template<> struct Position<OPone> { static const int value = 0; } template<> struct Position< OPtwo > { static const int value = 1; } template<> struct Position< OPthree > { static const int value = 2; } template<> struct Position< OPfour > { static const int value = 2; } I suppose there is no way to automagically generate the template specs from the enum? regards,

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[lambda] Understanding placeholders
by Robert Jones 15 Jan '09

15 Jan '09

Why is this wrong? #include "boost/lambda/lambda.hpp" #include "boost/lambda/bind.hpp" #include <iostream> int main( ) { using namespace boost :: lambda; int i = 2, j = 3; bind( bind( protect( _1 = _2 ), _2, _1 ), _1, _2 )( i, j ); std :: cout << "i = " << i << ", j = " << j << "\n"; } Thanks, Rob.

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[gil] io extensions
by Jan Boehme 15 Jan '09

15 Jan '09

Hi, I need to use the bmp io extension and tried the 'old' one from the googlecode repo which doesn't work against boost 1.37. Should I use the 'io_new' stuff and if so is there a bit of sample code how to use it in case the user interface has changed? Thanks, Jan.

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program options: unrecognized command-line options
by Deane Yang 15 Jan '09

15 Jan '09

I'm using the program options library to parse both command-line and configuration file parameters. I'd like to know how to find command-line arguments that are *not* registered and therefore not recognized by the parser. I want to be able to print a warning message like "Following arguments were ignored:....".

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boost::enable_shared_from_this why?
by Germán Diago 15 Jan '09

15 Jan '09

Hello, reading the documentation for enable_shared_from_this, I can't understand why this kind of base class is needed. In the example code in the documentation, we have: class Y: public enable_shared_from_this<Y> { public: shared_ptr<Y> f() { return shared_from_this(); } } int main() { shared_ptr<Y> p(new Y); shared_ptr<Y> q = p->f(); assert(p == q); assert(!(p < q || q < p)); // p and q must share ownership } Isn't this piece of code equivalent (since the two pointers share ownership): class Y { }; int main(int argc, char * argv[]) { shared_ptr<Y> p(new Y); shared_ptr<Y> q(p); ... }

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