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status of Boost.LockFree and Boost.Atomic. Boost.Endian libraries?
by Igor Hersht 28 Jan '12

28 Jan '12

Could you tell me what is the status of Boost.LockFree and Boost.Atomic <https://svn.boost.org/trac/boost/wiki/ReviewScheduleLibraries#Boost.Atomic> . Boost.Endian libraries? Boost.LockFree and Boost.Atomic <https://svn.boost.org/trac/boost/wiki/ReviewScheduleLibraries#Boost.Atomic> accepted a while ago, but I didn't find the libraries in the latest 1.49 beta. Similar question about Boost.Endian ($(boost)\spirit\home\support\detail\endian\endian.hpp). When/if the Boost.Endian is going to be accepted as a separate library.

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[interprocess] compilation errors with 1.48 on 64-bit Centos 5.5
by Daniel Herring 27 Jan '12

27 Jan '12

Hi, I started updating an application from Boost 1.35. It had a few compiler errors with 1.44, and things got worse with 1.48. While tracing down the new issues, problems were found with the distributed examples. For example, the following commands pass with 1.44 and 1.47 but fail with 1.48 (see attached logs). $ cd libs/interprocess/example $ ../../../bjam doc_managed_allocation_command > doc_managed_allocation_command.log $ ../../../bjam doc_managed_raw_allocation > doc_managed_raw_allocation.log All 1.44, 1.47, and 1.48 were built locally from the release source tarballs using a simple `./bootstrap.sh; ./bjam`. The example sources haven't changed during this period; so this may be a portability issue with the interprocess library itself. Here's some more info on the system. $ cat /etc/redhat-release CentOS release 5.5 (Final) $ g++ --version g++ (GCC) 4.1.2 20080704 (Red Hat 4.1.2-48) Copyright (C) 2006 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ rpm -qi gcc-c++ Name : gcc-c++ Relocations: (not relocatable) Version : 4.1.2 Vendor: CentOS Release : 48.el5 Build Date: Wed 31 Mar 2010 12:09:02 PM EDT Install Date: Mon 20 Sep 2010 06:02:55 AM EDT Build Host: builder17.centos.org Group : Development/Languages Source RPM: gcc-4.1.2-48.el5.src.rpm Size : 7824005 License: GPL Signature : DSA/SHA1, Mon 26 Apr 2010 07:41:02 PM EDT, Key ID a8a447dce8562897 URL : http://gcc.gnu.org Summary : C++ support for GCC Description : This package adds C++ support to the GNU Compiler Collection. It includes support for most of the current C++ specification, including templates and exception handling. The above commands do pass on release 1.48 when compiled using g++44 from the gcc44-c++-4.4.0-6.el5 package. However, that might not be an option for some of my users. Please let me know if more information is needed to debug the problem, if this is a known problem with gcc, etc. Thanks, Daniel

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Re: [Boost-users] mpi::allocator::construct function in gcc 4.6.2
by MM 27 Jan '12

27 Jan '12

> -----Original Message----- > From: MM [mailto:finjulhich@gmail.com] > Sent: 27 January 2012 18:54 > To: 'boost-users(a)lists.boost.org' > Subject: mpi::allocator::construct function in gcc 4.6.2 > > Hello, > > I get the following error: > > In file included from /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/vector:64:0, > from /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/bits/random.h:34, > from /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/random:50, > from /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_algo.h:67, > from /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/algorithm:63, > from /usr/include/boost/utility/swap.hpp:24, > from /usr/include/boost/swap.hpp:10, > from /usr/include/boost/array.hpp:44, > from /usr/include/boost/serialization/array.hpp:26, > from > /usr/include/boost/archive/detail/oserializer.hpp:58, > from > /usr/include/boost/mpi/detail/mpi_datatype_oarchive.hpp:14, > from > /usr/include/boost/mpi/detail/mpi_datatype_cache.hpp:13, > from /usr/include/boost/mpi/datatype.hpp:27, > from /usr/include/boost/mpi/packed_iarchive.hpp:21, > from /home/hich/trunk/serialization/contract.cpp:3: > /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_uninitialized.h: In > function 'void std::__uninitialized_default_n_a(_ForwardIterator, > _Size, _Allocator&) [with _ForwardIterator = char*, _Size = long > unsigned int, _Allocator = boost::mpi::allocator<char>]': > /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/bits/vector.tcc:477:8: > instantiated from 'void std::vector<_Tp, > _Alloc>::_M_default_append(std::vector<_Tp, _Alloc>::size_type) [with > _Tp = char, _Alloc = boost::mpi::allocator<char>, std::vector<_Tp, > _Alloc>::size_type = long unsigned int]' > /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_vector.h:592:4: > instantiated from 'void std::vector<_Tp, > _Alloc>::resize(std::vector<_Tp, _Alloc>::size_type) [with _Tp = char, > _Alloc = boost::mpi::allocator<char>, std::vector<_Tp, > _Alloc>::size_type = long unsigned int]' > /usr/include/boost/mpi/detail/packed_iprimitive.hpp:57:23: > instantiated from here > /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_uninitialized.h:576: > 6: error: no matching function for call to > 'boost::mpi::allocator<char>::construct(char*)' > /usr/lib/gcc/x86_64-redhat- > linux/4.6.2/../../../../include/c++/4.6.2/bits/stl_uninitialized.h:576: > 6: note: candidate is: > /usr/include/boost/mpi/allocator.hpp:168:8: note: void > boost::mpi::allocator<T>::construct(boost::mpi::allocator<T>::pointer, > const T&) [with T = char, boost::mpi::allocator<T>::pointer = char*] > /usr/include/boost/mpi/allocator.hpp:168:8: note: candidate expects 2 > arguments, 1 provided > > I am using c++0x. > > Should mpi::allocator::construct() be different? Is it required to > provide a 1-arg construct()? > > > > Regards, > > MM I have added a 1-arg construct() that constructs default T()to mpi::allocator and that seems to compile correctly ,

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Mersenne Twister 19937 suffers from "lattice effect"?
by Matthias Nagel 27 Jan '12

27 Jan '12

Hello, I tried to implement a two-dimensional multi-modal gaussian mixture and used the "mt19937" as the underlying generator. After I drew some samples (from the gaussian mixture) the outcome was not as I expected. After some bug tracking I suppose that the reason is something that is called "lattice effect" in German math literature. A pseudo-random generator suffers from a lattice effect, if one draws a sequence of samples, groups them together into N-dimensional vectors and these N-dimensional vectors are not uniformly distributed in the N-dimensional euclidean space. Does anybody know if the boost implementation has this problem? In the following, I will present my problem (and my algorithm) more elaborately, especially how I implemented my multi-model gaussian that is the origin of my problem: Lets assume we want a 2-dimensial gaussian mixture with M gaussian. 1) Create three lists (stl vector objects in my case), each with M entries. The first list stores the weight of each gaussian. The weights sum up to 1. The second list stores the mean value of each gaussian, i.e. a two-dimensional vector (in the mathematical sense, not the stl vector). The third list stores a 2-by-2 covariance matrix for each gaussian 2) Create a "mt19937" object, a "discrete_distribution" object and a "normal_distribution" object The "mt19937" is the common source of randomness for "discrete_distribution" and "normal_distribution". The "discrete_distribution" produces integers between 0 and M (number of gaussians) according the the given weights The "normal_distribution" is parameteized with mean = 0 and variance = 1, i.e. it is the standard normal distribtion. 3) Drawing one sample from the gaussian mixture - Draw one sample from the mt19937 and feed it into the discrete_distribution object. Denote the result by "index". - Draw a second sample from the mt19937 and feed it into the normal_distribution object. Denote the result by "u". - Draw a third sample from the mt19937 and feed it into the normal_distribution object. Denote the result by "v". - Pick up the mean vector and covariance matrix from the lists with respect to "index" - Transform the vector (u,v) according to the selected mean vector and covariance matrix. Denote the result "(x,y)". - Return (x,y) Lets remark that three samples are drawn from mt19937 to obtain one sample from the gaussian mixture. The result of this algorithm depends on the numbers of gaussians that build the mixture. 1) If M equals 1, the result looks fine. The (x,y) samples form an ellipsoid in the 2-dimensional euclidean space 2) If M equals 2, one gaussian looks like an ellipsoid, but it is too small. The second "gaussian" looks like a torus. Obviously all samples (u,v) with large coordinates are assigned to one gaussian, all (u,v) near zero are assigned to the other gaussian 3) If M equals 3, the "gaussians" look like segments of an ellipsoid. In each ellipsoid one third is missing. 4) For higher M the result is not correct either, but not as vivid and easily to explain as the "small" cases. As soon as I switch to random_device instead of mt19937 the phenomena disappears. ---------------------------------------------------------------------- Matthias Nagel Willy-Andreas-Allee 1, Zimmer 506 76131 Karlsruhe Telefon: +49 721 8695-1506 Telefax: +49 721 8695-4506 Mobil: +49 151 15998774 e-Mail: matthias.nagel(a)student.kit.edu ICQ: 499797758 Skype: nagmat84

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BOOST_RESULT_OF_USE_DECLTYPE not default on C++11 compilers
by Jeremiah Willcock 27 Jan '12

27 Jan '12

At least on GCC 4.6 in C++0x (C++11) mode, BOOST_RESULT_OF_USE_DECLTYPE is not set by default, preventing classes such as boost::transform_iterator from working on built-in lambda expressions. Is there a reason that the use of decltype is not on by default for compilers that support it, perhaps with a flag to force emulation mode (like Boost.Move supports)? -- Jeremiah Willcock

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Accessing exterior graph properties by name
by David Doria 26 Jan '12

26 Jan '12

Is there a way to "associate" an external property map to a name so that it can be retrieved from the graph? With a standard interior property, you can do: // Declare that you will be able to identify a property map by "vertex_data" namespace boost { enum vertex_data_t { vertex_data }; BOOST_INSTALL_PROPERTY(vertex, data); }; // Get the vertex_data property map from the graph typedef boost::property_map<Graph, boost::vertex_data_t>::type PropertyMapType; PropertyMapType propertyMap = get(boost::vertex_data, g); However, with the exterior properties, I can associate the property map with the nodes of the graph: typedef boost::property_map<GraphType, boost::vertex_index_t>::const_type indexMapType; indexMapType indexMap(get(boost::vertex_index, graph)); boost::vector_property_map<float, indexMapType> myMap(100, indexMap); but how would I then be able to, only having the graph object, get this map? That is, there was never any name, like "vertex_data" introduced in this case. Thanks, David

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was it created or opened when using boost::interprocess::shared_memory_object?
by Gehua Yang 26 Jan '12

26 Jan '12

Dear folks, I have been using Boost's Interprocess module for communication between several peer processes. In particular, I am using the shared_memory_object. As I was trying to create it with open_or_create_t flag (to ensure it finishes in an atomic operation), I cannot tell whether it was created or it was just opened. I would like to apply initialization when it was created but use its current information when it was opened. I hope there is a member function that can return this status. Best regards, Gehua Yang

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[BOOST USERS] [ BGL ] [GRAPH ] iterating through the vertices and edges of a filter graph
by srinivas boppu 26 Jan '12

26 Jan '12

Hello All, I need a small help in iterating through the vertices and edges of a filtered graph. Here is some sample code of the filtered graph. ( http://programmingexamples.net/wiki/CPP/Boost/BGL/FilteredGraph) ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- #include <iostream> #include <boost/graph/adjacency_list.hpp>#include <boost/array.hpp>#include <boost/graph/filtered_graph.hpp>#include <boost/graph/graph_utility.hpp> template <typename TGraph>struct vertex_id_filter{ bool operator()(const typename boost::graph_traits<TGraph>::vertex_descriptor& v) const { return 3 < v; // keep all vertx_descriptors greater than 3 }}; int main(){ using namespace boost; typedef adjacency_list<vecS, vecS, directedS, no_property, property<edge_weight_t, int> > Graph; typedef property_map<Graph, edge_weight_t>::type EdgeWeightMap; unsigned int numberOfVertices = 10; Graph g(numberOfVertices); for(unsigned int i = 0; i < numberOfVertices - 1; ++i) { add_edge(i, i+1, g); } std::cout << "Original graph:" << std::endl; boost::print_graph(g); vertex_id_filter<Graph> filter; filtered_graph<Graph, boost::keep_all, vertex_id_filter<Graph> > filteredGraph(g, boost::keep_all(), filter); // (graph, EdgePredicate, VertexPredicate) std::cout << "Filtered graph:" << std::endl; boost::print_graph(filteredGraph); return 0;} ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Here is my question. How do I iterate through the vertices and edges of "filteredGraph". I wanted to use the functions vertices( filteredGraph) and edges(filteredGraph) seems that we cannot use these functions as in the case of filtered graphs they return filtered_iterators. Please, can some one extend the above example and show me how to iterate through the vertices and edges. Thanks and Regards, Srinivas Boppu

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Ticket 4787 / Udp control headers.
by amit khandelwal 26 Jan '12

26 Jan '12

I was going through the 1.48 source code and I don't see it there. Is there a plan to add this patch or was it rejected due to some reason? Thanks, Amit Khandelwal

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boost filesystem
by John Emmas 26 Jan '12

26 Jan '12

Hello, I hope someone here will be able to help with this. Sorry, but the background is a little long-winded.... I've just discovered to my dismay that Microsoft's implementation of fstream, ifstream and ofstream are fatally flawed. I'm not sure if these characters will display correctly across this mailing list but consider the following character set:- ΔΗΜΗΤΡΗΣ which is apparently the Greek name "Dimitris". In an English locale, the following path would only be considered valid (by Windows) in a Unicode environment:- C:/Users/ΔΗΜΗΤΡΗΣ/some_file_name That's fine - because the user name doesn't contain valid English characters. However in Greece, that same path should qualify as a valid, non-Unicode file path and should therefore be openable without needing Unicode. For example, when building with MSVC this works:- #include <fcntl> int file = _open("C:/Users/ΔΗΜΗΤΡΗΣ/some_file_name", _O_RDONLY); However, this fails to work - even though it uses the same path:- #include <fstream> using std::fsrream; fstream file("C:/Users/ΔΗΜΗΤΡΗΣ/some_file_name", fstream::in | fstream::out); To cut a long story short, I noticed that libboost offers its own 'filesystem' implementation. Does boost::filesystem implement its own fstream, ifstream and ofstream? If so, would they likely suffer from the same problem (on Windows). If not, where can I find some examples of using boost::filesystem? Thanks, John

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