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Re: [Boost-users] Boost-users Digest, Vol 2650, Issue 4
by Robert Lupton the Good 27 Apr '11

27 Apr '11

> Sorry for the slow response. I simply defined the following: > > typedef boost::gil::pixel<float, boost::gil::gray_layout_t> gray_float_pixel_t; > typedef boost::gil::image<gray_float_pixel_t, false> gray_float_image_t; > typedef gray_float_image_t::view_t gray_float_view_t; > typedef gray_float_image_t::const_view_t gray_float_const_view_t; > > As Dr. Bourdev advised, I do not use with these typedefs any of the color conversion operations offered by GIL. Apparently those rely on the scaling properties of the float wrapper type. > > So far, all I have done with these typedefs is ... > > 1. construct views using interleaved_view and pixel data pointed to by [const] float*, as illustrated near the beginning of the GIL tutorial > 2. create x- and y- iterators for the views to apply row- and column-oriented algorithms? Sorry for _my_ slow response (I was in Japan). I don't care about colour conversions, but I think that these types will convert to integral types with scaling unless you add more boilerplate. I added the following -- but it may not all have been needed; this was quite a while ago and I was new to gil. I also have some remaining conversion problems where I have to rewrite expressions to make them compile, but this may be something else. Anyway, I'd really like to see native gil support for a complete set of NON-scaling types. namespace boost { namespace gil { /* * Define a type that's a pure float, without scaling into [0, 1] */ typedef float bits32f_noscale; GIL_DEFINE_BASE_TYPEDEFS(32f_noscale, gray) GIL_DEFINE_ALL_TYPEDEFS_INTERNAL(32f_noscale, dev2n, devicen_t<2>, devicen_layout_t<2>) template<> struct channel_multiplier<bits32f_noscale> : public std::binary_function<bits32f_noscale,bits32f_noscale,bits32f_noscale> { bits32f_noscale operator()(bits32f_noscale a, bits32f_noscale b) const { return a*b; } }; template <typename DstChannelV> struct channel_converter<bits32f_noscale, DstChannelV> : public std::unary_function<bits32f_noscale,DstChannelV> { DstChannelV operator()(bits32f_noscale x) const { return DstChannelV(x + 0.5f); } }; template <typename SrcChannelV> struct channel_converter<SrcChannelV,bits32f_noscale> : public std::unary_function<SrcChannelV,bits32f_noscale> { bits32f_noscale operator()(SrcChannelV x) const { return bits32f_noscale(x); } }; // // Totally specialised templates to resolve ambiguities // #define CONVERT_NOOP(T1, T2) \ template <> \ struct channel_converter<T1, T2> : public std::unary_function<T1, T2> { \ T2 operator()(T1 x) const { return static_cast<T2>(x); } \ }; \ \ template <> \ struct channel_converter<T2, T1> : public std::unary_function<T2, T1> { \ T1 operator()(T2 x) const { return static_cast<T1>(x); } \ } CONVERT_NOOP(unsigned char, short); CONVERT_NOOP(unsigned char, unsigned short); CONVERT_NOOP(unsigned char, int); CONVERT_NOOP(unsigned short, short); CONVERT_NOOP(unsigned short, int); CONVERT_NOOP(short, int); #undef CONVERT_NOOP

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[Units] Extension for units of data (and data rate)
by David, Robert (NSN - HU/Budapest) 27 Apr '11

27 Apr '11

Hello, I have created an extension to Boost.Units to support data sizes (bit / byte / kilobit / etc.) and data rates (bit per sec / Byte per sec / kbps / etc.), trying to mimic the logic behind the SI, GCS systems, so it might be added to the library after some review and fixes. Please see the attachment for the code (8 kB zip). Before that, a problem has to be fixed in my implementation: If I define the unit byte_per_second using make_scaled_unit and bit_per_second, I get a mile-long template error about not being able to figure out the prefix when I try to convert a quantity using that unit to string. I did a workaround for this problem using decltype(), but that requires including data_size.hpp and time.hpp to data_rate.hpp (although I don't know if it is a problem), and also, it only works on compilers supporting c++0x. You can see this workaround starting at line 40 in boostex/units/systems/data/data_rate.hpp. If I comment back line 41, and comment out line 44-45, the following will not compile: quantity<byte_per_sec_unit> speed(5.0 * byte_per_sec_unit); std::cout << speed << std::endl; however, auto speed = 5.0 * byte_per_sec_unit; std::cout << speed << std::endl; does (although only on compilers supporting c++0x auto), but prints out "second^-1 byte" instead of "byte/second" - effectively it does not call the name_string specialization for byte_per_sec in boostex/units/systems/data/io.hpp. All of this works correctly with the decltype() workaround. So my question is: can I define byte_per_sec (kilobyte_per_sec, megabyte_per_sec, etc.) in a c++03-compatible way? Br, Robert

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Boost::serialization problem when use archive in a loop
by mikesam 27 Apr '11

27 Apr '11

I have a problem with serialization, and I do not know how to solve it. Time to serialize the class a lot of growing when I do it in a loop. The first iteration takes about 40 ms, for example, but any other takes about 400 ms. class NODE { public: NODE(){} NODE* add(NODE* node) { children.push_back(node); return node; } ~NODE() { for(vector<NODE*>::const_iterator it = children.begin(); it != children.end(); ++it) { delete *it; } } vector<NODE*> children; private: friend class boost::serialization::access; template <typename Archive> void serialize(Archive &ar, const unsigned int version) { ar & children; } }; void save(NODE* main) { std::ofstream stream("test", std::ios::binary); boost::archive::binary_oarchive oa(stream, boost::archive::no_header); oa << main; } int main() { boost::timer t; NODE* main(new NODE()); for (int i=0; i<2000;i++) { NODE* subnode = main->add( new NODE()); for (int k=0; k<20; k++) subnode->add( new NODE()); } for (int i=0; i<4; i++) { t.restart(); save(main); cout<<"serialize: "<<t.elapsed()<<endl; } delete main; return 0; } -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-serialization-problem-when-use-arc… Sent from the Boost - Users mailing list archive at Nabble.com.

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[Boost][BGL] Dynamic Property, dynamic_get_failure.
by Mathieu - 27 Apr '11

27 Apr '11

Hi, I'm trying to generate random graphs (with random edge weight) and write them to a dot file, but I get this exception in the write_graphviz_dp() function : "what(): dynamic property get cannot retrieve value for property: weight." The code looks like this : typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, property<edge_index_t, int>, property<edge_weight_t, int> > graph; boost::minstd_rand gen; graph g; boost::generate_random_graph(g, 10, 30, gen, false, false); boost::randomize_property<boost::edge_weight_t>(g, gen); dynamic_properties dp; dp.property("weight", get(edge_weight, g)); boost::write_graphviz_dp(std::cout, g, dp, std::string("weight")); (don't pay attention to the random generator it's just to keep it simple). I've been looking at the examples and at the doc and it doesn't seem to me that I'm doing something wrong... but apparently I am. Thanks in advance!.

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Re: [Boost-users] Boost versions and the Interprocess library
by David Ohlemacher 27 Apr '11

27 Apr '11

Ion: I think you are probably quite right...and I am just going to have to find another method. I guess I could always give a quick try, but testing would become an issue. How would I really know there are no broken edge cases... Nat: The CORBA implementation works this way. I submit an IDL file that defines my object model (OM) to a website. What I get back is a library (binary, no source) and a pile of additional source files. Together they implement my OM using CORBA. They have dependencies on Boost 1.31. When I link my application, I link in autogenerated COBRA libs, Boost 1.31 libs, and include in various places Boost header files. | I'm perplexed what "closed source" means in this context. Maybe it's | because I don't understand the CORBA environment. But if you have a | prebuilt CORBA executable using Boost version 1.31, I don't understand | how that would constrain in any way the version of Boost you yourself | choose? Thanks for the input, -d

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[Polygon] using polygon for linesegment intersection
by gast128 26 Apr '11

26 Apr '11

Hello all, I was trying to use the Boost.Polygon library to test for line segment intersection. I define 2 polygons (lines) and use the Boolean operators of the polygon_set. However it gives an empty result: void TestBoostPolygonIntersectLineSegment() { using namespace boost::polygon::operators; typedef boost::polygon::polygon_data<int> Polygon; typedef boost::polygon::point_data<int> Point; typedef boost::polygon::polygon_set_data<int> PolygonSet; typedef std::vector<Polygon> PolygonVector; Point aPts1[] = { Point(0, 0), Point(10, 0) }; Point aPts2[] = { Point(5, 5), Point(5, -5) }; Polygon line1(aPts1, aPts1 + count_array(aPts1)); Polygon line2(aPts2, aPts2 + count_array(aPts2)); //both share point (5, 0) assert(boost::polygon::contains(line1, Point(5, 0))); assert(boost::polygon::contains(line2, Point(5, 0))); //eh..., expected it to be 1, but anyway assert(boost::polygon::size(line1) == 2); assert(boost::polygon::size(line2) == 2); PolygonSet ps1; PolygonSet ps2; ps1.insert(line1); ps2.insert(line2); PolygonSet ps3 = ps1 & ps2; //gives no result if (!ps3.empty()) //<--- { PolygonVector vec1; ps3.get(vec1); } } Also the documentation states that the size function gives the number of edges, but a line has only 1 edge: assert(boost::polygon::size(line1) == 2); //not 1?

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[MultiArray][Variant][Serialization]
by Johann Goetz 26 Apr '11

26 Apr '11

I am trying to serialize a multi_array object but keep the dimensions variable (I only want to support 1, 2 and 3 dimensions). So I attempted to create a Variant of the three multi_array's and the corresponding serialize methods as shown below, but I am getting a run-time error when for the 1-Dimensional case. Here is the minimal code example I came up with that shows the problem. I am using the boost SVN trunk as of this posting (April 26, 2011). Maybe I am implementing the load() method incorrectly for the multi_array. Should there be a special case for when Dim == 1? Running the program, I get the following error: > ./test test: /home/goetz/local/src/boost-trunk/boost/multi_array/multi_array_ref.hpp:487: boost::multi_array_ref<T, NumDims>& boost::multi_array_ref<T, NumDims>::operator=(const ConstMultiArray&) [with ConstMultiArray = boost::multi_array<float, 1ul>, T = float, long unsigned int NumDims = 1ul, boost::multi_array_ref<T, NumDims> = boost::multi_array_ref<float, 1ul>]: Assertion `std::equal(other.shape(),other.shape()+this->num_dimensions(), this->shape())' failed. Aborted (core dumped) /// Begin File: multiarray-variant-serialize.cpp /** * gcc compile command: * g++ multiarray-variant-serialize.cpp -otest -lboost_serialization * * to run: * ./test **/ #include <fstream> #include <string> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/array.hpp> #include <boost/serialization/variant.hpp> #include <boost/multi_array.hpp> typedef boost::variant< boost::multi_array<float,1>, boost::multi_array<float,2>, boost::multi_array<float,3> > multi_array_variant; namespace boost { namespace serialization { template<class Archive, typename T, size_t Dim> void save( Archive& ar, const boost::multi_array<T,Dim>& ma, const unsigned int version) { ar << boost::serialization::make_array(ma.shape(), Dim); ar << boost::serialization::make_array(ma.data(), ma.num_elements()); } template<class Archive, typename T, size_t Dim> void load( Archive& ar, boost::multi_array<T,Dim>& ma, const unsigned int version) { typedef typename boost::multi_array<T,Dim>::index index_t; boost::array<index_t,Dim> shape; ar >> boost::serialization::make_array(shape.data(), Dim); ma.resize(shape); ar >> boost::serialization::make_array(ma.data(), ma.num_elements()); } template<class Archive, typename T, size_t Dim> void serialize( Archive & ar, boost::multi_array<T,Dim>& ma, const unsigned int version) { split_free(ar, ma, version); } } /// namespace boost::serialization } /// namespace boost int main() { boost::multi_array<float,1> a1(boost::extents[5]); /// replacing the above line with either of the following two /// works as anticipated. Only the 1-Dimension breaks /// breaks at run-time. //boost::multi_array<float,2> a1(boost::extents[5][5]); //boost::multi_array<float,3> a1(boost::extents[5][5][5]); multi_array_variant a3 = a1; multi_array_variant a4; std::string filename = "archive.tmp"; { std::ofstream ofs(filename.c_str()); boost::archive::text_oarchive oa(ofs); oa << a3; } { std::ifstream ifs(filename.c_str()); boost::archive::text_iarchive ia(ifs); ia >> a4; } return 0; } /// EOF -- Johann T. Goetz

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[Review] Boost.Convert library is ongoing
by Edward Diener 26 Apr '11

26 Apr '11

Since there have been no reviews of this library yet, this is another reminder that formal review of the Boost.Convert library by Vladimir Batov is ongoing and ends on May 2. If you have felt that lexical_cast is not flexible enough for use, please take a look at this library and review it. *************** * Its Purpose * *************** The library builds on the past boost::lexical_cast experience, then takes those conversion-related ideas further to suit better today's applications and programing needs. It still offers simple, minimal interface, familiar conversion behavior and additionally provides: * throwing and non-throwing conversion-failure behavior; * support for the default/fallback value to be returned when conversion fails; * two types of the conversion-failure check - basic/simple and better/safe; * formatting support based on the standard std::streams and std::stream-based manipulators (like std::hex, std::scientific, etc.); * support for different locales; * support for boost::range-compliant char and wchar_t-based containers; * no DefaultConstructibility requirement for the Target/Destination type; * consistent framework to uniformly incorporate any type-to-type conversions, extensibility and additional room to grow. With its present support for string-to-type and type-to-string conversions it is an essential tool for applications making extensive use of configuration or MS-Windows-Registry-style files or having to process/prepare considerable amounts of data in, say, XML, etc. More so, it is easily extendable to accommodate, specialize and uniformly deploy new user-defined type-to-type conversions. ******************* * Where to get it * ******************* You can get the library, using Subversion, from https://svn.boost.org/svn/boost/sandbox/convert. The HTML documentation is part of the distribution and can be found at libs/convert/index.html in the distribution above. ******************** * Writing a review * ******************** The reviews and all comments should be submitted to the developers list, and the email should have "[convert] Review" at the beginning of the subject line to make sure it's not missed. Please explicitly state in your review whether the library should be accepted. The general review checklist: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Edward Diener, Review Manager

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boost.serializaion off by one error
by . lai 26 Apr '11

26 Apr '11

Hi all: Recently i come up with a problem in boost.serializaion when serializing primitives. with the following code, the output is: 1 0 input stream error But what i expect is: 1 input stream error test code: #include <boost/archive/text_iarchive.hpp> #include <boost/archive/text_oarchive.hpp> #include <sstream> #include <iostream> int main(int argc, char *argv[]) { std::stringstream stream; { boost::archive::text_oarchive oa(stream); int i = 1; oa << i; } try { boost::archive::text_iarchive ia(stream); int i = 0; ia >> i; std::cout << i << std::endl; i = 0; ia >> i; std::cout << i << std::endl; i = 0; ia >> i; std::cout << i << std::endl; }catch(boost::archive::archive_exception& ex){ std::cout << ex.what() << std::endl; } return 0; } the exception is threw in /usr/include/boost/archive/basic_text_iprimitive.hpp: basic_text_iprimitive:: template<class T> void load(T & t) { if(! is.fail()){ is >> t; //HERE SHOULD TEST IF READ IS SUCCUSSFULL return; } boost::serialization::throw_exception( archive_exception(archive_exception::input_stream_error) ); } In the function basic_text_iprimitive::load(T t), when T is a primitive, and is >> t fails, there is no exception threw, where there should. The same problem exsits in binary archive and text archive. Is it a bug or a feature? would it be fixed?

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Why can't I use boost graph write_graphviz with OutEdgeList=listS and VertexList=listS
by Allan Nielsen 25 Apr '11

25 Apr '11

Hi Why can't I compile the following simple app. If I changes listS to vecS every thing works just fine. (I'am using boost 1.46.1 and gcc 4.4.5) #include <iostream> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/graphviz.hpp> int main(int argc, const char *argv[]) { boost::adjacency_list< boost::listS, boost::listS, boost::bidirectionalS > g; boost::write_graphviz(std::cout, g); return 0; } Best regards Allan W. Nielsen

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