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[lambda & range] bind for transformed - how to do it.
by Robert Jones 29 Nov '11

29 Nov '11

In this code (fabricated) sequence, ages_by_bind compiles, but ages_by_lambda does not. I believe this is because the lambda version does not publish result_type to its resultant functors, since the increased generality of lambda makes this difficult or impossible to do. Is there any way I can get round this, as it currently makes the lambda/transformed combination completely unusable AFAICS. Thx, - Rob. #include <map> #include <vector> #include <string> #include <boost/bind.hpp> #include <boost/range.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/range/algorithm_ext/push_back.hpp> #include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> std::vector<int> ages_by_bind( const std::map<std::string, int> & people ) { using boost::adaptors::transformed; std::vector<int> result; boost::range::push_back( result, people | transformed( bind( & std::map<std::string, int>::value_type::second, _1 ) ) ); return result; } std::vector<int> ages_by_lambda( const std::map<std::string, int> & people ) { using boost::adaptors::transformed; namespace ll = boost::lambda; std::vector<int> result; boost::range::push_back( result, people | transformed( ll::bind( & std::map<std::string, int>::value_type::second, ll::_1 ) ) ); return result; }

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BGL with MPI
by Neiderer, Andrew M USA CIV (US) 29 Nov '11

29 Nov '11

I have libs/graph/example's working fine under RH in boost_1_48_0. But cannot get MPI working with BGL, e.g. libs/mpi/example/hello_world.cpp :-( When I translate using $g++ -I .../boost_1_48_0 -I .../boost_1_48_0/boost/mpi hello_world.cpp I get a bunch of errors, the first of which boost/mpi/config.hpp cannot find mpi.h. Not even sure where mpi.h is located and how it differs from mpi.hpp? Maybe if I solve this problem then all the other error messages, or most, will also go away. If there is a simple/obvious fix please let me know. Thank you. Andrew M. Neiderer US Army Research Laboratory

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[smart_ptr] make_shared imposes const ref.
by Robert Jones 29 Nov '11

29 Nov '11

Why is make_shared declared as template<typename T, typename Arg1 > shared_ptr<T> make_shared( Arg1 const & arg1 ); rather than template<typename T, typename Arg1 > shared_ptr<T> make_shared( Arg1 arg1 ); since the effect is that if you have a constructor that takes non-const references you cannot use make_shared( ) on it. Thx, - Rob.

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exception mechanism of boost.regex conflicts with QT lib.
by cat fa 29 Nov '11

29 Nov '11

a short piece of code: ///////////////////////////////////// boost::regex reg;; try { reg.assign( "[]d"); } catch(std::runtime_error &e) { //exception } ////////////////////////// this code runs well in Eclipse with MingW. When I copy this code in my QT project and run, it seems that QT lib cannot handle the exception which boost.regex lib throws. A run time termination warning shows as a result. I'm using win7 64bit. My QT is integrated with MingW 4.4 . Did any one encounter a similar problem? Could someone help me ?

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Re: [Boost-users] multi_array with large dimensions crashes
by Jothy 28 Nov '11

28 Nov '11

Hi Pierre, Sorry for the late reply. The code work now, thanks very much. But the programme crashes with a run-time error when the dimensions of the array are huge 500x500x500. This is probably due to the limitation of the 32 bit addrress space. Is there any other work around. I heard of creating arrays with strides and allocating them in different blocks of memory rather than in contiguos memory? Thanks again Jothy On Wed, Aug 24, 2011 at 6:25 PM, Pierre-Andre Noel < noel.pierre.andre(a)gmail.com> wrote: > Yes, 500, 300 and 400 were the example dimensions you used in your earlier > message. > > Did you got it to work? > > Pierre-André > > PS: This email was not sent to the whole list. > > > > On Wed, Aug 24, 2011 at 11:55 AM, Jothy <jothybasu(a)gmail.com> wrote: > >> You mean 500,300,400 are the required dimesnions and xDim,yDim,zDim are >> site_type parameters. >> >> So the code should be like below I guess for an array of [x][y][z] >> >> >> array_ref_type::size_type xDim(x), yDim(y), zDim(z); >> >> array_storage_type Storage(xDim*yDim*zDim); >> array_ref_type Array(&Storage.front(),boost::extents[xDim][yDim][zDim]); >> >> Thanks >> >> Jothy >> >> >> >> >> >> >> On Wed, Aug 24, 2011 at 3:51 PM, Pierre-Andre Noel < >> noel.pierre.andre(a)gmail.com> wrote: >> >>> >> I am not familiar with multi_array, but it seems that you are creating >>> a >1GB object on the stack. This will almost always crash. Try creating it >>> on the heap instead. Be prepared for std::bad_alloc. >>> >>> > But how to do this? I am new to c++. >>> >>> I suggest you to either 1. read on the operators "new" and "delete" or 2. >>> use a std::vector to allocate the memory then use a boost::multi_array_ref >>> to refer to it. Here's an example: >>> >>> #include <vector> >>> #include <boost/multi_array.hpp> >>> >>> int main() >>> { >>> typedef float data_type; >>> typedef std::vector<data_type> array_storage_type; >>> typedef boost::multi_array_ref<data_type,3> array_ref_type; >>> >>> array_ref_type::size_type xDim(500), yDim(300), zDim(400); >>> array_storage_type Storage(xDim*yDim*zDim); >>> array_ref_type >>> Array(&Storage.front(),boost::extents[xDim][yDim][zDim]); >>> // You may now use Array as usual. >>> } >>> >>> Hope it helps, >>> >>> Pierre-André Noël >>> >>> >>> On Wed, Aug 24, 2011 at 5:20 AM, Jothy <jothybasu(a)gmail.com> wrote: >>> >>>> Thanks for pointing this out. >>>> >>>> But how to do this? I am new to c++. >>>> >>>> Jothy >>>> >>>> >>>> On Tue, Aug 23, 2011 at 10:42 PM, Juraj Ivančić < >>>> juraj.ivancic(a)gmail.com> wrote: >>>> >>>>> On 23.8.2011. 12:18, Jothy wrote: >>>>> >>>>>> Hi all, >>>>>> >>>>>> I have just started to use boost libs. I am trying to create a large >>>>>> float array (mandatory for my purpose). it works fine till certain >>>>>> limit, but crashes above that. I think it about allocating memory in >>>>>> the >>>>>> stack. >>>>>> >>>>>> My code is like this >>>>>> >>>>>> typedefboost::multi_array<**float,3>array_type; >>>>>> typedefarray_type::indexindex; >>>>>> array_typeArray(boost::**extents[xDim][yDim][zDim]);//**500,300,400 >>>>>> for instance >>>>>> >>>>>> >>>>>> Can some one help me to resolve this? >>>>>> >>>>> >>>>> I am not familiar with multi_array, but it seems that you are creating >>>>> a >1GB object on the stack. This will almost always crash. Try creating it >>>>> on the heap instead. Be prepared for std::bad_alloc. >>>>> >>>>> HTH >>>>> >>>>> >>>>> ______________________________**_________________ >>>>> Boost-users mailing list >>>>> Boost-users(a)lists.boost.org >>>>> http://lists.boost.org/**mailman/listinfo.cgi/boost-**users<http://lists.boost.org/mailman/listinfo.cgi/boost-users> >>>>> >>>> >>>> >>>> _______________________________________________ >>>> Boost-users mailing list >>>> Boost-users(a)lists.boost.org >>>> http://lists.boost.org/mailman/listinfo.cgi/boost-users >>>> >>> >>> >>> _______________________________________________ >>> Boost-users mailing list >>> Boost-users(a)lists.boost.org >>> http://lists.boost.org/mailman/listinfo.cgi/boost-users >>> >> >> >> _______________________________________________ >> Boost-users mailing list >> Boost-users(a)lists.boost.org >> http://lists.boost.org/mailman/listinfo.cgi/boost-users >> > >

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BGL: invalidated/changing vertex_descriptor?
by Anders Wallin 28 Nov '11

28 Nov '11

Hi all, I have an directed adjacency_list graph with VertexListS=listS. I'm using this for a DCEL/winged-edge data-structure[1] for storing a planar graph. In this data structure each edge (src,trg) has a "twin edge" (trg,src). In the algorithm where I update the graph I have various sanity-checks, one of which is that the source and target of an edge should match the target and source of the twin edge. So if we have an edge and the associated twin_edge we can do: Vertex source = boost::source(edge, g); Vertex target = boost::target(edge, g); Vertex twin_source = boost::source(twin_edge, g); Vertex twin_target = boost::target(twin_edge, g); assert( source == twin_target ); assert( target == twin_source ); I have lately started seeing these asserts fail for some reason.The output, when the assert fails, can look like this: edge: (0x2f88850,0x2f8a7d0) twin_edge: (0x202f8a7d0,0x2f88850) Clearly this case will cause the above asserts to fail. I seem to pass the asserts many hundreds or thousands of times in my algorithm before at some point I get a failure. The failure always seems to happen at a different point in the code (with fairly large input, 10s or 100s of thousands of vertices). It is always of this same form, i.e. one vertex-descriptor address seems to have had "20" pre-pended from 0xAAAAAAA to 0x20AAAAAAA. If I do a release build which disables asserts I get segfaults instead when trying to access vertex-properties with the rouge vertex-descriptor. tested on two 64-bit ubuntu systems: (both show the behavior described above) Boost 1.42 with gcc 4.5.2 and Boost 1.46.1 with gcc 4.6.1 thanks for any input, (what's with the vertex_descriptors being output as seven hex-digits? why do I see a pre-pended "20"? what, if anything causes invalidation of vertex_descriptors?) Anders [1] http://en.wikipedia.org/wiki/Doubly_connected_edge_list

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broken documentation link
by niXman 28 Nov '11

28 Nov '11

Hi list. boost.pool broken documentation link: http://www.boost.org/doc/libs/1_48_0/libs/pool/doc/index.html >404 Not Found >File "/home/grafik/www.boost.org/archives/live/boost_1_48_0/libs/pool/doc/index.html" not found. >Unable to find file. Regards, niXman.

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[bind+signals] binding overloaded function + gcc4.6.2 = call of overloaded is ambiguous
by Bogdan Slusarczyk 28 Nov '11

28 Nov '11

Hi all, Such code can be built without problem using gcc3.4.3: typedef boost::signal< void () > Signal; Signal s; boost::bind( &Signal::operator(), &s ); but gcc4.6.2 returns: error: call of overloaded 'bind(<unresolved overloaded function type>, Signal*)' is ambiguous Is it expected behaviour? or problem in gcc4.6.2? Is there any solution except casting function pointer to particular type? Regards, Bogdan PS. I tried boost 1.38/1.48 and gcc 3.4.3/4.6.2

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[fusion] how apply action to to subset of fusion sequence
by Gennadiy Rozental 28 Nov '11

28 Nov '11

Hi, I need to apply action to first N elements in fusion sequence. What the best way to achieve it? Gennadiy

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[fusion] mutable action
by Gennadiy Rozental 28 Nov '11

28 Nov '11

Hi, How can I apply mutable action to the fusion sequence? It seems like fusion::for_each does not allow non const operator(). Gennadiy

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