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[BGL] adding behaviour to nodes and edges
by martin f krafft 22 Jun '05

22 Jun '05

I would like my nodes and edges to have behaviours. Bundled properties -- the method to attach struct instances to nodes and edges -- seems like the way to go. However, if that is the suggested method, then "bundled properties" is somewhat of a misnomer. What's the suggested way to attach behaviour to nodes and edges? I.e. I'd love to be able to iterate through vertices(G) with std::for_each and have it call a member function for each vertex. -- martin; (greetings from the heart of the sun.) \____ echo mailto: !#^."<*>"|tr "<*> mailto:" net@madduck invalid/expired pgp subkeys? use subkeys.pgp.net as keyserver! spamtraps: madduck.bogus(a)madduck.net the english take english for granted. but if we explore its paradoxes, we find that quicksand can work slowly.

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Problem using edge_descriptors as indices into an external property
by Andrea Olgiati 22 Jun '05

22 Jun '05

Folks, I've encountered a problem whilst compiling the following program, and I can't quite figure out why it shouldn't work. Whilst compiling usign boost 1.32.0 and gcc 3.3.4, I get cannot convert `boost::detail::edge_desc_impl<boost::bidirectional_tag, size_t>' to `int' for argument `2' to `const T& get(const T*, int) [with T = int]' I believe this is saying that edge descriptors cannot be used as indices into a property map (that is, "wm"). Why is this different from vertex descriptors, which are accepted as indices into "p" and "dist"? Any help appreciated. Thanks, Andrea #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/bellman_ford_shortest_paths.hpp> int main () { typedef boost::adjacency_list < boost::vecS, boost::vecS, boost::bidirectionalS > Graph; Graph G; std::vector < int > wm; std::vector < boost::graph_traits < Graph >::vertex_descriptor > p; std::vector < int > dist; boost::bellman_ford_shortest_paths (G, boost::num_vertices(G), &wm[0], &p[0], &dist[0], boost::closed_plus < int >(), std::less < int >(), boost::default_bellman_visitor ()); return 0; }

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[signal] custom connect/disconnect
by John Maguire 22 Jun '05

22 Jun '05

Hi all, I have a program where I have several signals, and I want an action to be taken when connect/disconnect occurs on them. I would prefer to avoid wrapping the calls, since it would reduce composibility. I would imagine that this isn't the first time that such a requirement has been made of signals, so I was wondering if someone could point me towards the standard solution for this? Regards, John

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[BGL] Question on prim_minimum_spanning_tree
by Wang Johny 22 Jun '05

22 Jun '05

Hi, there I am a new user of boost (in particular BGL). For my project, I am using the function of "prim_minimum_spanning_tree" to construct the minimum spanning tree. But I found a strange problem and hope to get your help. Specifically, I am following the sample code "prim-example.cpp" (using MSVC), with one modification to the weight property. That is, I am defining the weight property as property < edge_weight_t, float > not the original one property < edge_weight_t, int > And I found by doing so, the function of "prim_minimum_spanning_tree" return wrong results (no edge is returned at all). But the original version using "property < edge_weight_t, int >" definition works well. So I am wondering if I missed something to make user-defined weitgh property work for this function. Any suggestion is welcome. Thank you very much. Best regards, Shenai Problematic code: /////////////////////////////////////////////////////////////////////////////////////////////////// typedef adjacency_list < vecS, vecS, undirectedS, property<vertex_distance_t, int>, property < edge_weight_t, float > > Graph; typedef std::pair < int, int >E; const int num_nodes = 5; E edges[] = { E(0, 2), E(1, 1), E(1, 3), E(1, 4), E(2, 1), E(2, 3), E(3, 4), E(4, 0) }; float weights[] = { 1.0f, 2.0f, 1.0f, 2.0f, 7.0f, 3.0f, 1.0f, 1.0f }; Graph g(num_nodes); property_map<Graph, edge_weight_t>::type weightmap = get(edge_weight, g); for (std::size_t j = 0; j < sizeof(edges) / sizeof(E); ++j) { graph_traits<Graph>::edge_descriptor e; bool inserted; tie(e, inserted) = add_edge(edges[j].first, edges[j].second, g); weightmap[e] = weights[j]; } std::vector < graph_traits < Graph >::vertex_descriptor > p(num_vertices(g)); property_map<Graph, vertex_distance_t>::type distance = get(vertex_distance, g); property_map<Graph, vertex_index_t>::type indexmap = get(vertex_index, g); prim_minimum_spanning_tree(g, *vertices(g).first, &p[0], distance, weightmap, indexmap, default_dijkstra_visitor()); for (std::size_t i = 0; i != p.size(); ++i){ if (p[i] != i){ TRACE("I am here"); } } /////////////////////////////////////////////////////////////////////////////////////////////////// --------------------------------- Do You Yahoo!? 150万曲MP3疯狂搜，带您闯入音乐殿堂美女明星应有尽有，搜遍美图、艳图和酷图 1G就是1000兆，雅虎电邮自助扩容！

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style: overloading vs default parameters
by Noel Yap 22 Jun '05

22 Jun '05

Is there any particular reason why at least some boost code uses default parameters. IME, I've found the using overloading is preferable. For example, when using boost::bind, one would have to explicitly give the default parameters whereas one wouldn't if overloading were used. Also, using overloading rather than default parameters when a new function interface is needed can potentially break less client code (eg code that uses the type of the function won't break if overloading were used). Given this, I'd like to hear some arguments for using default arguments over overloading (outside of constructors, of course, where one may not have much of a choice). Thanks, Noel

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boost building question
by H 22 Jun '05

22 Jun '05

Hi, In the Jamfile help it says: --builddir=DIR Build in this location instead of building within the distribution tree. Recomended! Does this mean the build is not the same as the install, i.e. while building, files are being stored somewhere and removed after final installation? Thank you, H.

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Boost.Function: How does the template param mechanism work?
by Brian Braatz 21 Jun '05

21 Jun '05

My question is, given: boost::function< int (char, long) > func(&f); how is it possible to pass the (char,long)? (I tried to receive this in a template as a single template param, or as three , but neither worked) I have been studying the headers, but the indirection used (FTSE :) ) is making it hard for me to figure this one out. The reason I am asking I is I am trying to clean up the syntax of some template params and I would like to use this technique. i.e. I would like to write: struct A {}; struct B {}; struct C {}; struct D {}; struct E {}; struct F {}; typedef MyThingdef< (A,B), (C,D), (E,F) > splat; instead of typedef MyThingdef< A,B, C,D, E,F > splat; Any direction on things to research or dig into appreciated. Thanks Brian

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Serialization truncation?: xml_oarchive, ostringstream vs. ofstream
by Benjamin.Sternlieb＠ubs.com 21 Jun '05

21 Jun '05

Hi, I was trying out boost serialization and ran into a snag. If I serialize the same object onto two xml_oarchives, one constructed with a ostringstream and one constructed with an ofstream, I get differing results - the file based xml is well formed, but the string based xml is missing its final closing tag. Here is the generating code snippet: // now serialize ostringstream os; boost::archive::xml_oarchive ar(os); ofstream ofs("/home/sternlbe/boo.xml"); boost::archive::xml_oarchive ar2(ofs); Portfolio& port = *p; ar << BOOST_SERIALIZATION_NVP(port); ar2 << BOOST_SERIALIZATION_NVP(port); string s = os.str(); LOG_DEBUG(logger) << "Xml string: \n" << s; For the file output, I get the (correct) result: <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="3"> <port class_id="0" tracking_level="1" version="0" object_id="_0"> <m_id>2124433</m_id> <m_name>This is a stub!</m_name> <m_isLoaded>0</m_isLoaded> </port> </boost_serialization> However, the string result is missing the final line (closing tag): <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="3"> <port class_id="0" tracking_level="1" version="0" object_id="_0"> <m_id>2124433</m_id> <m_name>This is a stub!</m_name> <m_isLoaded>0</m_isLoaded> </port> Any thoughts? Thanks in advance, Ben Visit our website at http://www.ubs.com This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. E-mail transmission cannot be guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. The sender therefore does not accept liability for any errors or omissions in the contents of this message which arise as a result of e-mail transmission. If verification is required please request a hard-copy version. This message is provided for informational purposes and should not be construed as a solicitation or offer to buy or sell any securities or related financial instruments.

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boost log and vc 7
by Oliver Schoenborn 21 Jun '05

21 Jun '05

Hi, I am trying to create a dll for boost log v1.33(ie a dll containing code compiled from functions.cpp, log.cpp and log_manager.cpp) using VC++ 7.1 on WinXP. I get the same error whether I do it from VisualStudio or using bjam. The bjam file is : dll libboost_log : functions.cpp log.cpp log_manager.cpp : <include>c:/Boost/include/boost-1_32 <include>../../include ; and the vc-Link fails with the message that it "cannot open file 'boost_log-vc71-mt-gd-1_32.lib'". I have *no* idea where or how vc-Link comes to the conclusion that it needs that lib file. Any ideas? Thanks, Oliver p.s. The output from bjam session is: $ bjam ...patience... ...found 310 targets... ...updating 2 targets... vc-Link libboost_log.dll\vc-7_1\debug\threading-multi\libboost_log.dll libboost_log.dll\vc-7_1\debug\threading-multi\libboost_log.lib LINK : fatal error LNK1104: cannot open file 'boost_log-vc71-mt-gd-1_32.lib' CALL "C:\Program Files\Microsoft Visual Studio .NET 2003\VC7\bin\VCVARS32.BAT" >nul "C:\Program Files\Microsoft Visual Studio .NET 2003\VC7\bin\link" /nologo /INCREMENTAL:NO /DEBUG /DLL /subsystem:console /out:"libboost_log.dll\vc-7_1\debug\threading-multi\libboost_log.dll" /IMPLIB:"libboost_log.dll\vc-7_1\debug\threading-multi\libboost_log.lib" @"libboost_log.dll\vc-7_1\debug\threading-multi\libboost_log.CMD" ...failed vc-Link libboost_log.dll\vc-7_1\debug\threading-multi\libboost_log.dll libboost_log.dll\vc-7_1\debug\threading-multi\libboost_log.lib... ...failed updating 2 targets... --------------------------------------------- Oliver Schoenborn Consultant, Modelling & Simulation Greenley & Associates Inc. 5 Corvus Court Ottawa, ON K2E 7Z4 Canada D: (613) 247-0342 x217 C: (613) 371-4773 F: (613) 225-4281 www.greenley.ca <http://www.greenley.ca/>

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Re: [Boost-users] Reusing indexing base from multi_array_ref
by Sohail Somani 20 Jun '05

20 Jun '05

I should be slightly more careful, version without accesses below: #include <boost/multi_array.hpp> int main() { typedef boost::multi_array<double, 2> array_type; typedef boost::multi_array_ref<double,2> array_type_ref; typedef array_type::index_range range; typedef boost::multi_array_types::extent_range extent_range; array_type A(boost::extents[extent_range(1,4)][extent_range(1,10)]); // [1,4),[1,10) A[3][9]=95; array_type::array_view<1>::type f = A[boost::indices[range()][9]]; assert(f[2]==A[3][9]); // Would like to have assert(f[3]==A[3][9]). f.reindex(1); assert(f[3]==A[3][9]); // Do I *have* to reindex in this way? } Thanks.

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