January 2009 - Boost-users - lists.preview.boost.org

[boost] Futures Review Starts Today - January 5, 2009
by Tom Brinkman 06 Jan '09

06 Jan '09

Futures Review Starts Today - January 5, 2009 Braddock Gaskill http://braddock.com/~braddock/future Anthony Williams http://www.justsoftwaresolutions.co.uk/files/n2561_future.hpp Please review one or both libraries for submission to boost. Apparently, Anthony Williams' submission has also been sumbitted the C++ standards committee. Status unknown. As always, here are some questions you might want to answer in your review(s): What is your evaluation of the design(s)? What is your evaluation of the implementation(s)? What is your evaluation of the documentation? What is your evaluation of the potential usefulness of the library(s)? Did you try to use the library? With what compiler(s)? Did you have any problems? How much effort did you put into your evaluation(s)? A glance? A quick reading? In-depth study? Are you knowledgeable about the problem domain? Do you think the libraries should be accepted into Boost as-is or should they be merged? Apparently, there has been various discussions about these two libraries last six months. The authors will need to bring us up to date as to why they want their libraries to be reviewed seperately. Also, each author should evaluate each others library and point out the differences in their implentations. These will serve as useful discussion points. The ideal outcome in my mind would be a resubmitted submission, incorporating the best ideas from each. Tell me if you share this view or what is your preferred result. As always, your reviews will certainly assist the authors in improving their libraries even further. Thank you in advance. Please feel free to participate in any discussion even if your not going to provide a full review. Review Manager Tom Brinkman _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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Re: [Boost-users] [spirit2] Containers, Tuples and Sequence attributes
by Joel de Guzman 05 Jan '09

05 Jan '09

Joel de Guzman wrote: Ooops, sorry, wrong list. Please disregard. Cheers, -- Joel de Guzman http://www.boostpro.com http://spirit.sf.net

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Adding Vertex to Graph
by Damian 05 Jan '09

05 Jan '09

I attempted to post this before but are not sure it went up so here it is again. Basically i have created a map with the key being a unique number and the value being a pointer to a class. Up until this point i have been using add_edge(1,2,graph) where 1 and 2 are unique numbers assigned to the classes. I now need to be able to add vertex and thought it would be something like add_vertex(3, graph) however it is not. How do i go about add a vertex with the id 3 Cheers Damian

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Question on multiindex erase return value
by Ramesh 05 Jan '09

05 Jan '09

As per the erase documentation http://www.boost.org/doc/libs/1_36_0/libs/multi_index/doc/reference/ord_ind… erase method can take an iterator position as argument & if erase is successful, it returns an iterator pointing to the next item or end(). Assuming i have only one item in the container, after a successful erase, the iterator would anyway point to end(). Supposing erase failed, will it still return me end()? How do I distinguish between a successful erase & failed erase involving iterator? Thanks Ramesh

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[thread] locking and time
by Ernst Murnleitner 05 Jan '09

05 Jan '09

Hello, I have some questions about threads. It would be very nice if somebody could clarify. 1) recursive_timed_mutex: It is possible to use a time period for locking of a recursive_timed_mutex by using the approprioate timed_lock(). But there is not lock class with such a constructor? 2) (recursive timed) shared mutex: Is it not possible to lock with a period of time instead of ptime? 3) change of system time: What happens in a timed_lock if the system time is advanced by e.g. one hour? Is there a difference of using ptime or time_period? 4) read/writer mutex: if there are some recursive locks by one thread and this thread should become the writer, do I run in a deadlock? 5) What is the meaning of the various ..._lock_t (e.g. )? Is there a documentation? ad 1) There seems only to be a constructor with ABSOLUTE time: unique_lock(Lockable & m,boost::system_time const& abs_time) ad 2) There seems no possibility to use boost::posix_time::time_period for locking. ad 3) If the clock is set to one hour in the future. I think a timed_lock could take one hour at this moment? If yes, does it happen also if I give a time period? ad 4) if it is possible to recusively lock in one thread, it should be possible to make the thread a writtrer thread (exclusive owner) independently on how often it was locked before. Is this possible? ad 5) Only internal usage?: unique_lock(Lockable& m_,adopt_lock_t); unique_lock(Lockable& m_,defer_lock_t); unique_lock(Lockable& m_,try_to_lock_t) Thank you in advance, Greetings, Ernst

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[Units] Molecular units base_units trouble: please help
by Christopher Bruns 05 Jan '09

05 Jan '09

I am using the Boost Units library to support molecule scale dynamic simulations, but I am pretty sure I am using Boost Units wrong. I am looking for some guidance and explanations for some confusing compile errors I get (see below). I am creating a units system using a mixture of custom base_units (mass, amount, charge), scaled base units based on si::base_units (time, length), and unmodified si::base_units (plane_angle, solid_angle, temperature). The full set of base units I intend to use are as follows: * time in picoseconds * mass in daltons * length in nanometers * amount in molecules * angle in radians * solid angle in steradians * charge in elementary charges * temperature in kelvin * [I'm ignoring luminous intensity for now] Perhaps I am being too picky, because I can build up a molecular dynamics scale units system if I explicitly create every base_unit myself. But I would like to take maximum advantage of the SI units infrastructure that is already available. I suspect that directly using some of the SI base_units would be more efficient than the method I am currently using, which establishes conversion factors to the SI units. Some of these conversion factors are 1.0 (unity). Listing 1 shows a stripped down example using three base_units: mass, length, and time. This program compiles and runs, but notice the conversion factors of 1.0 in the BOOST_UNITS_DEFINE_CONVERSION_FACTOR macros toward the end. Listing 1: Compiles and runs, but I had to explicitly create every base_unit. THIS PROGRAM WORKS -- LOOK FARTHER DOWN FOR THE ONE THAT FAILS *** BEGIN LISTING 1 *** #include <boost/units/conversion.hpp> #include <boost/units/systems/si.hpp> #include <iostream> namespace si = boost::units::si; namespace md { using boost::units::length_dimension; using boost::units::mass_dimension; using boost::units::time_dimension; using boost::units::quantity; using boost::units::unit; using boost::units::scaled_base_unit; using boost::units::scale; using boost::units::static_rational; // length struct meter_base_unit : boost::units::base_unit<meter_base_unit, length_dimension, 1> { static std::string name() { return "meter"; } static std::string symbol() { return "m"; } }; typedef scaled_base_unit< meter_base_unit, scale<10, static_rational<-9> > > nanometer_base_unit; // mass struct dalton_base_unit : boost::units::base_unit<dalton_base_unit, mass_dimension, 2> { static std::string name() { return "Dalton"; } static std::string symbol() { return "Da"; } }; // time struct second_base_unit : boost::units::base_unit<second_base_unit, time_dimension, 3> { static std::string name() { return "second"; } static std::string symbol() { return "s"; } }; typedef scaled_base_unit< second_base_unit, scale<10, static_rational<-12> > > picosecond_base_unit; // create the units system typedef boost::units::make_system< nanometer_base_unit, dalton_base_unit, picosecond_base_unit >::type md_units_system; // define quantity types typedef unit<length_dimension, md_units_system> nanometer_unit; BOOST_UNITS_STATIC_CONSTANT(nanometer, nanometer_unit); BOOST_UNITS_STATIC_CONSTANT(nanometers, nanometer_unit); typedef quantity<nanometer_unit> length_t; typedef unit<mass_dimension, md_units_system> dalton_unit; BOOST_UNITS_STATIC_CONSTANT(dalton, dalton_unit); BOOST_UNITS_STATIC_CONSTANT(daltons, dalton_unit); BOOST_UNITS_STATIC_CONSTANT(atomic_mass_unit, dalton_unit); BOOST_UNITS_STATIC_CONSTANT(atomic_mass_units, dalton_unit); typedef quantity<dalton_unit> mass_t; typedef unit<time_dimension, md_units_system> picosecond_unit; BOOST_UNITS_STATIC_CONSTANT(picosecond, picosecond_unit); BOOST_UNITS_STATIC_CONSTANT(picoseconds, picosecond_unit); typedef quantity<picosecond_unit> time_t; } // namespace md // length conversions BOOST_UNITS_DEFINE_CONVERSION_FACTOR( md::meter_base_unit, si::meter_base_unit, double, 1.0); // mass conversions BOOST_UNITS_DEFINE_CONVERSION_FACTOR( md::dalton_base_unit, si::kilogram_base_unit, double, 1.6605388628e-27); // time conversions BOOST_UNITS_DEFINE_CONVERSION_FACTOR( md::second_base_unit, si::second_base_unit, double, 1.0); using namespace md; using namespace std; int main () { md::time_t timeStep = 0.002 * picoseconds; cout << "time step = " << timeStep << endl; mass_t carbonMass = 12.0 * daltons; cout << "carbon mass = " << carbonMass << endl; length_t bondLength = 0.15 * nanometers; cout << "bond length = " << bondLength << endl; // nonsense, but exercises composite dimensions cout << "composite value = " << timeStep * bondLength << endl; return 0; } *** END LISTING 1 *** Actually, I can directly base the LENGTH dimension on the SI units by changing line 27 of Listing 1 from 26: typedef scaled_base_unit< 27: meter_base_unit, 28: scale<10, static_rational<-9> > 29: > nanometer_base_unit; to 26: typedef scaled_base_unit< 27: si::meter_base_unit, // <== note si prefix 28: scale<10, static_rational<-9> > 29: > nanometer_base_unit; So shouldn't I be able to do the same thing for all of the other SI units? I would have thought so. But doing the same thing for the the TIME dimension always results in trouble, in my experience. Witness listing 2, below. Listing 2: Fails to compile; lots of indecipherable template errors. Time dimension is based on si::second_base_unit. THIS PROGRAM FAILS TO COMPILE *** BEGIN LISTING 2 *** #include <boost/units/conversion.hpp> #include <boost/units/systems/si.hpp> #include <iostream> namespace si = boost::units::si; namespace md { using boost::units::mass_dimension; using boost::units::time_dimension; using boost::units::quantity; using boost::units::unit; using boost::units::scaled_base_unit; using boost::units::scale; using boost::units::static_rational; // mass struct dalton_base_unit : boost::units::base_unit<dalton_base_unit, mass_dimension, 1> { static std::string name() { return "Dalton"; } static std::string symbol() { return "Da"; } }; // time typedef scaled_base_unit< si::second_base_unit, scale<10, static_rational<-12> > > picosecond_base_unit; // create the units system typedef boost::units::make_system< dalton_base_unit, picosecond_base_unit >::type md_units_system; // define quantity types typedef unit<mass_dimension, md_units_system> dalton_unit; BOOST_UNITS_STATIC_CONSTANT(dalton, dalton_unit); BOOST_UNITS_STATIC_CONSTANT(daltons, dalton_unit); BOOST_UNITS_STATIC_CONSTANT(atomic_mass_unit, dalton_unit); BOOST_UNITS_STATIC_CONSTANT(atomic_mass_units, dalton_unit); typedef quantity<dalton_unit> mass_t; typedef unit<time_dimension, md_units_system> picosecond_unit; BOOST_UNITS_STATIC_CONSTANT(picosecond, picosecond_unit); BOOST_UNITS_STATIC_CONSTANT(picoseconds, picosecond_unit); typedef quantity<picosecond_unit> time_t; } // namespace md // mass conversions BOOST_UNITS_DEFINE_CONVERSION_FACTOR( md::dalton_base_unit, si::kilogram_base_unit, double, 1.6605388628e-27); using namespace md; using namespace std; int main () { md::time_t timeStep = 0.002 * picoseconds; cout << "time step = " << timeStep << endl; mass_t carbonMass = 12.0 * daltons; cout << "carbon mass = " << carbonMass << endl; // nonsense, but exercises composite dimensions cout << "composite value = " << timeStep * carbonMass << endl; return 0; } *** END LISTING 2 *** One way to get listing 2 to compile and run is to change line 20 from 19: struct dalton_base_unit : 20: boost::units::base_unit<dalton_base_unit, mass_dimension, 1> to 19: struct dalton_base_unit : 20: boost::units::base_unit<dalton_base_unit, mass_dimension, -1000> // <== The program compiles when I use a large negative value for the base_unit id. But the documentation states that negative values are reserved. I am a bad boy for even trying. In any case, that "-1000" trick only works when the TIME dimension is the only dimension that is directly based on SI units. ERROR MESSAGES FROM LISTING 2: **** small sample of the top of the compile errors I get with unmodified Listing 2: **** 1>C:\cygwin\home\Christopher\svn\dnamodel\include\boost/units/detail/linear_algebra.hpp(207) : error C2976: 'boost::units::detail::determine_extra_equations_skip_zeros_impl<true,true>::apply' : too few template arguments 1> C:\cygwin\home\Christopher\svn\dnamodel\include\boost/units/detail/linear_algebra.hpp(217) : see declaration of 'boost::units::detail::determine_extra_equations_skip_zeros_impl<true,true>::apply' 1> C:\cygwin\home\Christopher\svn\dnamodel\include\boost/units/detail/linear_algebra.hpp(259) : see reference to class template instantiation 'boost::units::detail::determine_extra_equations_skip_zeros_impl<true,false>::apply<RowsBegin,RemainingRows,CurrentColumn,TotalColumns,Result>' being compiled 1> with 1> [ 1> RowsBegin=boost::units::list<boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::list<boost::units::dim<boost::units::time_base_dimension,boost::units::static_rational<1>>,boost::units::dimensionless_type>>::type,boost::units::list<boost::units::static_rational<1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::list<boost::units::list<boost::units::static_rational<1>,boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::dimensionless_type>::type,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::dimensionless_type>>, 1> RemainingRows=2, 1> CurrentColumn=0, 1> TotalColumns=2, 1> Result=boost::units::list<boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::list<boost::units::dim<boost::units::time_base_dimension,boost::units::static_rational<1>>,boost::units::dimensionless_type>>::type,boost::units::list<boost::units::static_rational<1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::list<boost::units::list<boost::units::static_rational<1>,boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::dimensionless_type>::type,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::dimensionless_type>> 1> ] 1> C:\cygwin\home\Christopher\svn\dnamodel\include\boost/units/detail/linear_algebra.hpp(538) : see reference to class template instantiation 'boost::units::detail::determine_extra_equations<RemainingColumns,is_done>::apply<RowsBegin,TotalColumns,Result>' being compiled 1> with 1> [ 1> RemainingColumns=2, 1> is_done=false, 1> RowsBegin=boost::units::list<boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::list<boost::units::dim<boost::units::time_base_dimension,boost::units::static_rational<1>>,boost::units::dimensionless_type>>::type,boost::units::list<boost::units::static_rational<1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::list<boost::units::list<boost::units::static_rational<1>,boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::dimensionless_type>::type,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::dimensionless_type>>, 1> TotalColumns=2, 1> Result=boost::units::list<boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::list<boost::units::dim<boost::units::time_base_dimension,boost::units::static_rational<1>>,boost::units::dimensionless_type>>::type,boost::units::list<boost::units::static_rational<1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::list<boost::units::list<boost::units::static_rational<1>,boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::dimensionless_type>::type,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::dimensionless_type>> 1> ] 1> C:\cygwin\home\Christopher\svn\dnamodel\include\boost/units/detail/linear_algebra.hpp(828) : see reference to class template instantiation 'boost::units::detail::make_square_and_invert<Matrix>' being compiled 1> with 1> [ 1> Matrix=boost::units::list<boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::list<boost::units::dim<boost::units::time_base_dimension,boost::units::static_rational<1>>,boost::units::dimensionless_type>>::type,boost::units::list<boost::units::static_rational<1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::list<boost::units::list<boost::units::static_rational<1>,boost::units::list<boost::units::detail::calculate_base_dimension_coefficients_func<false>::apply<boost::units::dimensionless_type>::type,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>,boost::units::dimensionless_type>> 1> ] 1> C:\cygwin\home\Christopher\svn\dnamodel\include\boost/units/detail/linear_algebra.hpp(1032) : see reference to class template instantiation 'boost::units::detail::normalize_units<T>' being compiled 1> with 1> [ 1> T=boost::units::list<boost::units::scaled_base_unit<boost::units::si::second_base_unit,boost::units::scale<10,boost::units::static_rational<-12>>>,boost::units::list<md::dalton_base_unit,boost::units::dimensionless_type>> 1> ] [snip] ****** END snippet of compile errors ********* Environment details: I am developing in Visual Studio Express 9.0 on Windows XP at the moment. The version of boost::units I am using is from subversion on January 3, 2009. I would feel better if I could reuse several of the base_units from SI. Just reusing length and not the others seems painfully sloppy. I welcome any comments that might nudge me in the right direction. Thanks in advance for any help. --Chris Bruns

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Re: [Boost-users] [Proto] automaitcally convert class to proto literal
by Daniel Oberhoff 05 Jan '09

05 Jan '09

> Daniel Oberhoff a Ã©crit : > > I might have gotten the terms wrong. But the way I got it working now is > > with using proto::lit which turns things into literals. I tried > > subclassing terminal with my array class, but that way the tree did not >> keep a reference to the array, and thus could not be evaluated as such. > Just make a array_data class that contains your data and make your user > level array class extends terminal<array_data>::type. The vec3 example > in the doc is exacly this and I used variations of this for like 4 or 5 > array like DSEL since proto is available. Ok, I looked into that. Works better than my previous approaches. Though I would like it much better if I don't have to split my class into an internal data class and a user interface, since I would like to use the whole interface in the proto evaluators. Also, since the extends mechanism makes the data class end up a member of the derived class it is hard to access the derived class from the base class. Is this fundamentally impossible? Naively I would like to write: class array : public proto::extends< proto::terminal< array >::type, array > { [...] }; though this is not possible since the extends mechanism makes the expr class a member of the extending class, and thus the class would have to contain itself in the end, which is, of course, impossible. -- --- Daniel Oberhoff Fraunhofer FIT Schloss Birlinghoven 53754 Sankt Augustin, Germany Tel.: +49-(0)-2241-14-3486 Fax.:+49 (0) 2241/14-2080

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[BGL] vertex_index_t, edge_index_t?
by Geoff Hilton 05 Jan '09

05 Jan '09

Quick question: Given an arbitrary graph of type: typedef boost::adjacency_list< boost::listS, //out edge list selector boost::vecS, //vertex list selector boost::bidirectionalS, //directedness selector VertexPropertyWrapper_type, EdgePropertyWrapper_type> Graph_type; Where: typedef boost::property< boost::vertex_index_t, unsigned long long, MyVertexProperty> VertexPropertyWrapper_type; And: typedef boost::property< boost::edge_index_t, unsigned long long, MyEdgeProperty> EdgePropertyWrapper_type; How does setting edge/vertex_index_t as an interior property affect..anything? I saw in a post on this list somewhere a while ago that this was a necessary workaround for something or other (that which I don't recall now). In the post it actually said to use "int" (or was it unsigned int?) rather than unsigned long long but in any case I left it as unsigned long long and it hasn't affected anything negatively thus far so I left it that way. I believe I put it at unsigned long long because the type that was suggested for the *_index_t happened to match a weight type used in the post, but whether that was intentionally and implicitly or unintentionally and explicitly I don't remember. Thank you, Geoff

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[BGL] Bundled properties and property maps
by Alex Brooks 05 Jan '09

05 Jan '09

Hi, I've used BGL before for representing graphs, but this is my first time with an algorithm. I've been stuck for many hours trying to define a property map with bundled properties, I'd really appreciate some help. I'm using gcc4.3, boost 1.34. An example program and the compiler error are: ------------------------------------------------------------- #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/astar_search.hpp> using namespace std; class Point { public: double p_[2]; }; struct EdgeProp { double cost; }; typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, Point*, EdgeProp> Graph; typedef boost::graph_traits<Graph>::vertex_descriptor VertexRef; class AStarHeuristic : public boost::astar_heuristic<Graph, double> { public: double operator()( VertexRef vertex ) const {return 0.0;} }; // exception for termination struct FoundGoal {}; // // A* Visitor that terminates when we reach the goal // class AStarVisitor : public boost::default_astar_visitor { public: AStarVisitor( const VertexRef &goal ) : goal_(goal) {} template <class Graph> void examine_vertex( VertexRef vertex, Graph &g ) { if( vertex == goal_ ) throw FoundGoal(); } private: VertexRef goal_; }; bool searchThroughGraph( const Graph &graph, VertexRef start, VertexRef goal, std::vector<VertexRef> &shortestPath ) { AStarHeuristic aStarHeuristic; AStarVisitor aStarVisitor( goal ); typedef boost::property_map<Graph, double EdgeProp::*>::type EdgeWeightMap; EdgeWeightMap edgeWeightMap = get(&EdgeProp::cost, graph); std::vector<VertexRef> predecessors(num_vertices(graph)); try { astar_search( graph, start, aStarHeuristic, boost::weight_map(edgeWeightMap). predecessor_map(&predecessors[0]). visitor(aStarVisitor) ); } catch ( const FoundGoal& ) { shortestPath.clear(); for ( VertexRef vertex = goal;; vertex = predecessors[vertex] ) { shortestPath.push_back( vertex ); if ( predecessors[vertex]==vertex ) break; } std::reverse( shortestPath.begin(), shortestPath.end() ); return true; } // If we get to here, we couldn't reach the goal return false; } int main() { Graph graph; std::vector<VertexRef> path; searchThroughGraph(graph,0,1,path); return 0; } ------------------------------------------------------------- /home/a.brooks/shh/src/libs/prm/test/stupid.cpp: In function ‘bool searchThroughGraph(const Graph&, VertexRef, VertexRef, std::vector<unsigned int, std::allocator<unsigned int> >&)’: /home/a.brooks/shh/src/libs/prm/test/stupid.cpp:64: error: conversion from ‘boost::bundle_property_map<const boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, Point*, EdgeProp, boost::no_property, boost::listS>, boost::detail::edge_desc_impl<boost::undirected_tag, unsigned int>, EdgeProp, const double>’ to non-scalar type ‘searchThroughGraph(const Graph&, VertexRef, VertexRef, std::vector<unsigned int, std::allocator<unsigned int> >&)::EdgeWeightMap’ requested ------------------------------------------------------------- Does anyone know what might be wrong? More generally, I'm a bit mystefied by the "<Graph, double EdgeProp::*>::type" syntax -- can anyone give me any pointers about what this syntax means, or where I can look it up? (googling for colon-colon-star doesn't help much). I also tried pattern-matching from the documentation page about bundled properties (the weight_map(get(&Highway::miles, map)) example) but couldn't get this to compile either. Is this example correct? Thanks very much in advance, Alex

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Boost multiindex: Usage of erase
by Ramesh 05 Jan '09

05 Jan '09

Hello Joaquin, I am trying to erase members of a container selectively, I get a compile error (no matching function found) at the point where I use erase (highlighted line) below: Could you please point out whats wrong with the usage? Thanks /Ramesh Here is the code: ------------- struct MyMap { Adapter *pAdapter; unsigned long timestamp; MyMap(Adapter * param_Adp, unsigned long param_timestamp ): pAdapter(param_Adp), timestamp(param_timestamp) {} ~MyMap(){ pAdapter = 0; timestamp = 0; } }; struct pAdapter{}; struct timestamp{}; typedef multi_index_container< MyMap, indexed_by < ordered_unique< tag <pAdapter>, BOOST_MULTI_INDEX_MEMBER(MyMap, Adapter *, pAdapter) >, ordered_unique< tag <timestamp>,BOOST_MULTI_INDEX_MEMBER(MyMap, unsigned long, timestamp) > > > tMap; class ACtr { private: tMap AContainer; public: // Constructor ACtr(); //Destructor ~ACtr(); //Remove stale bool pruneBad(); }; bool ACtr::pruneBad { for ( tMap::index_iterator<timestamp>::type it = AContainer.get<timestamp>().begin(), it_end = AContainer.get<timestamp>().end();it != it_end; count++) { it = AContainer.erase(it); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ } } ----

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