July 2007 - Boost-users - lists.preview.boost.org

Using boost graphic lib (newbie)
by E B 30 Jul '07

30 Jul '07

I need to display a graph . Therefore I need to compute coordinate of each node (XY) and I plan to use BGL which provide algorithms for this purpose. After having looked at the test examples, I can not see how to implement a graph and run one of the layout algorithms. Does anybody have any experience on using BGL ? My node stuct is struct { string name; int x; int y; } and I have a vector of pair that contain the edges (vector<pair<node*,node*> >). I need to feed the node.x and node.y by using my own struct or another ones provided I get the X Y.

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Stupid ostringstream question
by Bill Lear 30 Jul '07

30 Jul '07

I have been searching the world in vain for a stringstream that works with a static buffer, and does not use the heap for memory allocation. We have an application that uses lots (12-16Gb) of memory. This puts a strain on the memory allocation routines, and when we want to create a small string we find that stringstream is very, very expensive, and sprintf into a static buffer much, much faster. Does boost provide anything like this? This actually came up when we realized that boost lexical_cast was using stringstream. When we replaced it with sprintf, our runtimes (when memory usage was very high) went down significantly. I should also point out that ANYTHING we did with dynamic memory at that point in the application (vector::push_back, for example) was hideously slow. I'd like to have the best of both worlds: the relatively clear syntax of the ostringstream inserters, working on a static buffer. Any help (code samples especially) appreciated. Bill

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[Boost.Build v2] Please help updating my build process from v1 (1.33.1) to v2 (1.34.1)
by Ames, Andreas (Andreas) 30 Jul '07

30 Jul '07

Hi all, as most of my colleagues insist on using Visual Studio, I have made a vcproj-wrapper around Boost.Build v1 for 1.33.1. The Jamfile looks like this: <Jamfile> project-root ; BOOST_LOCAL_STAGE_DIR ?= stage ; rule Pseudo ( target : libname : kind : variant : name_prefix ? ) { LIBNAME = $(libname) ; LIBKIND = $(kind) ; VARIANT = $(variant) ; REALNAME = $(name_prefix)$(LIBNAME) ; REALNAME ?= $(LIBNAME) ; NOTFILE $(target) ; DEPENDS $(target) : $(BOOST_LOCAL_STAGE_DIR)/$(LIBKIND)/$(LIBNAME)/$(VARIANT) ; stage $(BOOST_LOCAL_STAGE_DIR)/$(LIBKIND)/$(LIBNAME)/$(VARIANT) : <$(LIBKIND)>@boost/libs/$(LIBNAME)/build/boost_$(REALNAME) : <sysinclude>../../../boost <debug-symbols>on <debug-store>database <runtime-build>$(VARIANT) <runtime-link>dynamic <native-wchar_t>on : $(VARIANT) ; } Pseudo signals_lib_debug : signals : lib : debug ; Pseudo signals_lib_release : signals : lib : release ; </Jamfile> Furthermore I've created a Jamrules and a boost-build.jam like follows: <Jamrules> project boost : ../../../boost ; </Jamrules> <boost-build.jam> boost-build ../../../boost/tools/build/v1 ; </boost-build.jam> From my vcproj-files I can then just invoke bjam with the appropriate target and TOOLS-spec. 1) Unfortunately this doesn't work any longer with Boost.Build v2. After changing boost-build.jam in the obvious way, I just get bjam to display: error: Could not find parent for project at '.' error: Did not find Jamfile or project-root.jam in any parent directory. although the Jamfile is definitely there. The same thing happens, when I change the name to Jamfile.v2. 2) Skimming over the docs, I don't see Jamrules (which was previously needed) mentioned. Is it still necessary? 3) Finally, the build wrapper needs to be selfcontained (we get it from our repository), so site-config.jam and user-config.jam must not be mandatory. I just wonder, where to specify my 'using' rule(s) (like 'using msvc : 8.0 ;'). TIA, aa -- Andreas Ames | Programmer | Comergo GmbH | ames AT avaya DOT com Sitz der Gesellschaft: Stuttgart Registergericht: Amtsgericht Stuttgart - HRB 22107 Geschäftsführer: Andreas von Meyer zu Knonow, Udo Bühler, Thomas Kreikemeier

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[filesystem] Using path in shared library fault (?)
by Hughes, James 30 Jul '07

30 Jul '07

Hello all, I am using filesystem::path is a shared library called 'common', to initialise a static var. static boost::filesystem::path p("/home/me"); However, this give a seg fault (Linux, gcc) when the shared library is loaded. I am guessing this is an issue with the filesytem library not being loaded in at the time of the loading of 'common' (when the static var is initialised) - hence the seg fault. Its only an issue with the static variable, as all other uses of path in the library work fine. Is there any way round this? James This message (including any attachments) contains confidential and/or proprietary information intended only for the addressee. Any unauthorized disclosure, copying, distribution or reliance on the contents of this information is strictly prohibited and may constitute a violation of law. If you are not the intended recipient, please notify the sender immediately by responding to this e-mail, and delete the message from your system. If you have any questions about this e-mail please notify the sender immediately.

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stream + file_descriptor_source + closing
by Tomasz Noiński 30 Jul '07

30 Jul '07

Hi, I'm trying to use boost::iostreams for a project I'm writing and I have a problem: It seems that the destructor of boost::iostreams::stream<boost::iostreams::file_descriptor_source> closes the file descriptor. I really need to be able to close this file descriptor manually and I can't find any way to do it. Note that file_descriptor_source has a constructor parameter specifying if the descriptor should be closed in file_descriptor_source destructor or not. It perfectly works - it's boost::iostreams::stream destructor that forces closing the description, not file_descriptor_source destructor. A short code illustrating this problem (for Linux): --- 8< --- #include <iostream> #include <boost/iostreams/device/file_descriptor.hpp> #include <boost/iostreams/stream.hpp> #include <cstring> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <errno.h> using namespace std; using namespace boost::iostreams; int main() { int fd = open("/etc/fstab", O_RDONLY); clog << "fd=" << fd << endl; { file_descriptor_source source(fd, false); stream<file_descriptor_source> strm(source); string s; strm >> s; clog << "first line: " << s << endl; } int closeRet = close(fd); int closeErrno = errno; clog << "closing result: " << closeRet << ", " << strerror(closeErrno) << endl; } --- 8< --- The behaviour I would expect is the close() at the end succeeding. However, it returns -1 with errno=EBADF. Is this the expected behaviour or a bug? TIA, Noix

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boost thread read_write_mutex
by Fei Liu 30 Jul '07

30 Jul '07

Just a question, I don't see any big bold note that the related read/write mutex or locks should not be used...What's the story of reader/writer's mutex in boost::thread? Fei

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[Boost.Graph] Compiler warning in dijkstra_shortest_paths
by Ewgenij Sokolovski 30 Jul '07

30 Jul '07

Hello. I use the Boost.Graph with the dijkstra_shortest_paths algorithm in my graph application. All works fine. But while compiling with the options -Wall -W I get a strange compiler warning: /usr/include/boost/graph/dijkstra_shortest_paths.hpp:80: Warning: »bfs_vis$m_decreased« is used in this function uninitialised This was the last line of the warning because it is quite long in its complete version. I translated the line above from German because I use a German version of g++, so maybe it sounds in the English version a little bit different. But the meaning remains the same:) Does anybody know what that is supposed to mean? Is something wrong with my program or is it a bug in dijkstra_shortest_paths? Here is the warning in the complete version: /usr/include/boost/graph/dijkstra_shortest_paths.hpp: In function »void boost::detail::dijkstra_dispatch2(const VertexListGraph&, typename boost::graph_traits<G>::vertex_descriptor, DistanceMap, WeightMap, IndexMap, const Params&, ColorMap) [with VertexListGraph = boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, boost::no_property, float, boost::no_property, boost::listS>, DistanceMap = float*, WeightMap = boost::adj_list_edge_property_map<boost::undirected_tag, float, float&, long unsigned int, boost::property<boost::edge_bundle_t, float, boost::no_property>, boost::edge_bundle_t>, IndexMap = boost::vec_adj_list_vertex_id_map<boost::no_property, long unsigned int>, Params = boost::bgl_named_params<boost::adj_list_edge_property_map<boost::undirected_tag, float, float&, long unsigned int, boost::property<boost::edge_bundle_t, float, boost::no_property>, boost::edge_bundle_t>, boost::edge_weight_t, boost::bgl_named_params<float*, boost::vertex_distance_t, boost::no_property> >, ColorMap = boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::default_color_type*, std::vector<boost::default_color_type, std::allocator<boost::default_color_type> > >, boost::vec_adj_list_vertex_id_map<boost::no_property, long unsigned int>, boost::default_color_type, boost::default_color_type&>]«: /usr/include/boost/graph/dijkstra_shortest_paths.hpp:80: Warning: »bfs_vis$m_decreased« is used in this function uninitialised Greetings Ewgenij -- Ist Ihr Browser Vista-kompatibel? Jetzt die neuesten Browser-Versionen downloaden: http://www.gmx.net/de/go/browser

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Problem Bjam
by question boost 30 Jul '07

30 Jul '07

Hi, using Code Blocks i got the folowing message: ld.exe "Cannot find -lboost_filesystem-mgw-mt-s-l_33_l". So I did :cd /jam source location/then build.bat Then, i put the following variables: path=C:\Program Files\CodeBlocks\bin BOOST_BUILD_PATH=C:\Documents and Settings\Administrateur\Bureau\boost_1_33_1\boost_1_33_1\tools\build\v2 BOOST_ROOT=C:\Documents and Settings\src\boost It is not the right things to do => i get the message again. My question is: What are the right things to do in order not to get the message any more? Thank You _________________________________________________________________ Windows Live Messenger vous offre 30 nouvelles émoticônes gratuites, installées directement dans votre Messenger ! http://www.emoticones-messenger.fr/

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How to build only Boost.Iostreams with compression filter support on Windows XP using MinGW
by Benjamin Lau 30 Jul '07

30 Jul '07

Good evening, Pardon my ignorance, or my poor documentation reading skills, but I am unable to build Boost.Iostreams with compression filter support on Windows XP using MinGW. I am using Boost 1.34.1, zlib 1.2.3 and bzip2 1.0.4. I tried the following command lines but to no avail: bjam --toolset=gcc -sNO_COMPRESSION=0 -sNO_BZIP2=0 -sBZIP2_LIBPATH=C:\bzip2-1.0.4 -sBZIP2_SOURCE=C:\bzip2-1.0.4 -sNO_ZLIB=0 -sZLIB_LIBPATH=C:\zlib-1.2.3 -sZLIB_SOURCE=C:\zlib-1.2.3 stage or bjam --toolset=gcc --NO_COMPRESSION=0 --NO_BZIP2=0 --BZIP2_LIBPATH=C:\bzip2-1.0.4 --BZIP2_SOURCE=C:\bzip2-1.0.4 --NO_ZLIB=0 --ZLIB_LIBPATH=C:\zlib-1.2.3 --ZLIB_SOURCE=C:\zlib-1.2.3 stage I searched through the Boost.Iostreams documentation, the Boost.Jam documentation, and the Boost.Build V2 documentation. Boost.Jam documentation indicates that the former should work, but Boost.Build V2 seems to use very little of or not at all of the -s flag for Boost.Jam, so I tried the latter. The result of both commands were the same, Boost.Iostreams was built without the compression filters. However, I do get 12 "warning: Unable to construct ./stage-unversioned" as the first output from Boost.Jam, after which it says "...patience..." and continues with the building process. Thank you in advance for assisting me in my problem, and in case I have missed out something critical yet obvious, and hence resulting in my failure, I apologise for not reading carefully enough. Thank you and have a nice day Benjamin Lau

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Zhang has Tagged you :)
by Zhang Shenpeng 29 Jul '07

29 Jul '07

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