// typedef boost::property_map::type EdgeWeightMap; // EdgeWeightMap edgeWeightMap = get(&EdgeProp::cost, graph);

Option A works, but is a bit ugly. Option B is what you suggested, but it gives the following error:

Gotta a const Graph also: property_map Andrew Sutton andrew.n.sutton@gmail.com

Hi Alex, I was able to compile your original code by changing the line typedef boost::property_map::type EdgeWeightMap; to typedef boost::property_map::const_type EdgeWeightMap; hope this will help, Dmitry Alex Brooks escribió:

...

Gotta a const Graph also:

property_map

Any other ideas?

Thanks again,

Alex

/usr/include/c++/4.3/ext/new_allocator.h:82: error: 'const _Tp* __gnu_cxx::new_allocator<_Tp>::address(const _Tp&) const [with _Tp = const double]' cannot be overloaded /usr/include/c++/4.3/ext/new_allocator.h:79: error: with '_Tp* __gnu_cxx::new_allocator<_Tp>::address(_Tp&) const [with _Tp = const double]'

Not good... astar passes its graph by non-const reference so when it declares: typedef typename property_traits<WeightMap>::value_type D; typename std::vector<D>::size_type D is apparently const double, and std::vector<const double> doesn't seem to work too well - not to mention the fact that you probably want to assign values to elemetns of that vector :) I guess your only solution is to pass the graph by non-const reference. This may be a bug, but I'm not entirely sure. Andrew Sutton andrew.n.sutton@gmail.com

Alex Brooks wrote:

...

Gotta a const Graph also:

property_map

This line compiles now, but I get a new compile error from the astar_search line. The important bits are:

typedef boost::property_map::type EdgeWeightMap; EdgeWeightMap edgeWeightMap = get(&EdgeProp::cost, graph);

std::vector<VertexRef> predecessors(num_vertices(graph)); astar_search( graph, start, aStarHeuristic, boost::weight_map(edgeWeightMap). predecessor_map(&predecessors[0]). visitor(aStarVisitor) );

The error is:

/usr/include/c++/4.3/bits/allocator.h:84: instantiated from 'std::allocator<const double>' /usr/include/c++/4.3/bits/stl_vector.h:75: instantiated from 'std::_Vector_base' /usr/include/c++/4.3/bits/stl_vector.h:176: instantiated from 'std::vector' /usr/include/boost/graph/astar_search.hpp:360: instantiated from 'void boost::detail::astar_dispatch1(VertexListGraph&, typename boost::graph_traits<G>::vertex_descriptor, AStarHeuristic, CostMap, DistanceMap, WeightMap, IndexMap, ColorMap, const Params&) [with VertexListGraph = const boost::adjacency_list, AStarHeuristic = AStarHeuristic, CostMap = boost::detail::error_property_not_found, DistanceMap = boost::detail::error_property_not_found, WeightMap = boost::bundle_property_map, boost::detail::edge_desc_impl, EdgeProp, const double>, IndexMap = boost::vec_adj_list_vertex_id_map, unsigned int>, ColorMap = boost::detail::error_property_not_found, Params = boost::bgl_named_params, boost::detail::edge_desc_impl, EdgeProp, const double>, boost::edge_weight_t, boost::no_property> > >]' /usr/include/boost/graph/astar_search.hpp:394: instantiated from 'void boost::astar_search(VertexListGraph&, typename boost::graph_traits<G>::vertex_descriptor, AStarHeuristic, const boost::bgl_named_params&) [with VertexListGraph = const boost::adjacency_list, AStarHeuristic = AStarHeuristic, P = AStarVisitor, T = boost::graph_visitor_t, R = boost::bgl_named_params, boost::detail::edge_desc_impl, EdgeProp, const double>, boost::edge_weight_t, boost::no_property> >]' /home/a.brooks/shh/src/libs/prm/test/stupid.cpp:83: instantiated from here /usr/include/c++/4.3/ext/new_allocator.h:82: error: 'const _Tp* __gnu_cxx::new_allocator<_Tp>::address(const _Tp&) const [with _Tp = const double]' cannot be overloaded /usr/include/c++/4.3/ext/new_allocator.h:79: error: with '_Tp* __gnu_cxx::new_allocator<_Tp>::address(_Tp&) const [with _Tp = const double]'

Any other ideas?

Thanks again,

Alex

I'm having the same problem though mine (with MSVC9) says: error C2678: binary '=': no operator found which takes a left-hand operand of type 'const Weight' (or there is no acceptable conversion) c:\program files\boost\boost_1_37_0\boost\property_map.hpp 161 A follow-up would be greatly appreciated. Thanks, Geoff

Dmitry Bufistov wrote:

Geoff Hilton wrote:

...

I'm having the same problem though mine (with MSVC9) says:

error C2678: binary '=': no operator found which takes a left-hand operand of type 'const Weight' (or there is no acceptable conversion) c:\program files\boost\boost_1_37_0\boost\property_map.hpp 161

A follow-up would be greatly appreciated.

Thanks, Geoff

You can try to use boost::remove_const<Weight>::type

Regards, Dmitry

I appreciate your suggestion, but the reason I'm getting the error is because I'm trying to make the code const-correct, until yesterday code that raised this issue would have the graph parameter be rendered non-const as a temporary "fix", but that's not good style, I'm looking to remedy this by making the code const-correct now. :) If there's no other solution then I'll revert the const-correctedness changes until there is one, but I have a hard time believing this to be the case. Thanks, Geoff

Dmitry Bufistov wrote:

Geoff Hilton wrote:

...

I'm having the same problem though mine (with MSVC9) says:

error C2678: binary '=': no operator found which takes a left-hand operand of type 'const Weight' (or there is no acceptable conversion) c:\program files\boost\boost_1_37_0\boost\property_map.hpp 161

A follow-up would be greatly appreciated.

Thanks, Geoff

You can try to use boost::remove_const<Weight>::type

Regards, Dmitry

To help things along, here's the code in question: Note: graph variable is of type const Graph&. const boost::property_map::const_type eprop = boost::get(&EdgeProp::weight, graph); const boost::property_map::const_type vindex = boost::get(boost::vertex_index, graph); const vertex_descriptor firstVertex = *GetGraphBeginVertexIterator(graph); PredecessorMap preds = PredecessorMap(numVertices); DistanceMap dists = DistanceMap(numVertices); boost::bellman_ford_shortest_paths(graph, numVertices, weight_map(eprop) .predecessor_map(boost::make_iterator_property_map(preds.begin(), vindex)) .distance_map(boost::make_iterator_property_map(dists.begin(), vindex)) .root_vertex(firstVertex) .distance_combine(Combiner()) .distance_compare(Comparer(currentOffset)) ); Also, my Weight type has an explicit constructor which takes a POD convertible to 0, a requirement imposed it seems by line 155 of bellman_ford_shortest_paths.hpp. Why doesn't the algorithm take a weight of value zero as a parameter and use it instead? Anyway, because of this explicit constructor I've added a (typical) assignment operator (not sure if this is relevant, but I'm mentioning it just in case). I should also note that out of curiosity I commented out line 103 of bellman_ford_shortest_paths.hpp which is: function_requires >(); Commenting out the above line allows my code as written above to compile, otherwise it fails with the error written in my original response (quoted above). Whether the compiled code (with line 103 commented out) functions as expected I don't know, I haven't tested it. Thanks, Geoff

Dmitry Bufistov wrote:

Geoff Hilton escribió:

...

Note: graph variable is of type const Graph&.

[skip]

...

Also, my Weight type has an explicit constructor which takes a POD convertible to 0, a requirement imposed it seems by line 155 of bellman_ford_shortest_paths.hpp. Why doesn't the algorithm take a weight of value zero as a parameter and use it instead?

Anyway, because of this explicit constructor I've added a (typical) assignment operator (not sure if this is relevant, but I'm mentioning it just in case).

I should also note that out of curiosity I commented out line 103 of bellman_ford_shortest_paths.hpp which is:

function_requires >();

Commenting out the above line allows my code as written above to compile, otherwise it fails with the error written in my original response (quoted above). Whether the compiled code (with line 103 commented out) functions as expected I don't know, I haven't tested it.

Thanks, Geoff

It looks like the problem is with template struct ReadablePropertyMapConcept;

The following code fails to compile:

#include #include

using namespace boost; struct EdgeProp { double weight; };

typedef boost::adjacency_list graph_t; int main() { typedef boost::property_map::const_type WeightMap; typedef boost::graph_traits::edge_descriptor Edge; function_requires >(); }

You may try to change the boost/property_map.hpp as follows: (in the version 1.37 the line number is 165) typename typename property_traits<PMap>::value_type val; to the typename remove_const::type val;

Does it work for you?

Regards, Dmitry

Thanks Dmitry, it does work! I do wonder though, isn't there a better fix? What about specializing ReadablePropertyMapConcept specifically for const properties, or does that not make sense with concept classes? I'm okay with modifying BGL code, but the remove_const makes me feel dirty. This sounds like something that should be brought up with BGL maintainers... Geoff

Thanks Dmitry, it does work! I do wonder though, isn't there a better fix?

...

What about specializing ReadablePropertyMapConcept specifically for const properties, or does that not make sense with concept classes? I'm okay with modifying BGL code, but the remove_const makes me feel dirty.

This sounds like something that should be brought up with BGL maintainers...

Geoff

I believe that something is bad with the const version of bundled_properties. Andrew, what do you think?

This is the only report - to my knowledge - of this kind of problem. I'm not entirely that the best solution is to change the BGL. I'll have to take a good look tomorrow morning. Andrew Sutton andrew.n.sutton@gmail.com