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Is there a spatialIndex in boost?
by Peng Yu 22 Oct '08

22 Oct '08

Hi, Some message mentioned spatialindex. I'm wondering where the package homepage is at? Thanks, Peng

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Is there a way to generate the library names used by auto_link.hpp
by Patrick Harris 22 Oct '08

22 Oct '08

I'd like to be able to use the generated library names to automatically add a linker delay load option but the auto_link.hpp file undefs the lib name and some of the other defines used. Is there a supported way of getting the generated names other than duplicating and customising bits of the auto_link.hpp file? Thanks

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[graph] Newbie question: iterator shows vertices not added, always lo .. hi
by Chris Lott 21 Oct '08

21 Oct '08

Hi, I am new to the Boost graph library and trying to learn from examples in the documentation. I would like to ask about the simple vertex iterator's behavior. Below is sample code. In a nutshell, the program adds some edges to a Boost graph, then prints the vertices. The vertex numbers added are not contiguous: the loop basically adds edges between vertices 0, 1, 2, 6, and 7; no edges are added for vertices 3, 4, 5. Then I use a vertex iterator to show tine in- and out-degree of each vertex. My expectation was that the iterator would only show me the vertices for which I added edges, but instead it shows vertices from 0..7, essentially from the low value to the high value. This seems to be a feature, but I don't know where to look to find an explanation. Perhaps this behavior is dictated by my choices of data structures vecS? So far I have been relying on the online documentation, which I find to be quite difficult to use. For example, the web site doesn't seem to have a comprehensive index to Boost generic types and functions, just that alone would be an enormous help. Is the Boost book is (substantially?) better than using the online docs, or is it just the same content on paper? Please advise, thanks for your help. chris... -------- [code] #include <iostream> // for std::cout #include <utility> // for std::pair #include <algorithm> // for std::for_each #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> int /* GraphExample_ */ main(int,char*[]) { // create a typedef for the Graph type typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS> Graph; // Make convenient labels for the vertices enum { A, B, C, X, Y, Z, D, E, N }; const int num_vertices = N; typedef std::pair<int, int> Edge; Edge edge_array[] = { Edge(A,B), Edge(A,D), Edge(C,A), Edge(D,C), Edge(C,E), Edge(B,D), Edge(D,E) }; const int num_edges = sizeof(edge_array)/sizeof(edge_array[0]); // Declare a graph object with the specified number of vertices. Graph g(num_vertices); // add the edges to the graph object // Each vertex is an integer. for (int i = 0; i < num_edges; ++i) boost::add_edge(edge_array[i].first, edge_array[i].second, g); // Iterate through the vertices and print them out. // This iterator seems to be simply 0.. (largest vertex number). // Some vertices were never added as part of any edge, yet the // loop below shows them anyhow. typedef boost::graph_traits<Graph>::vertex_iterator vertex_iter; std::pair<vertex_iter, vertex_iter> vp; for (vp = vertices(g); vp.first != vp.second; ++vp.first) { vertex_iter iter = vp.first; boost::graph_traits<Graph>::vertex_descriptor v = *iter; int in = boost::in_degree(v, g); std::cout << "Vertex " << v << " has in degree " << in << std::endl; int out = boost::out_degree(v, g); std::cout << "Vertex " << v << " has out degree " << out << std::endl; } return 0; } [/code]

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[mutli_index] class reference available? / How to detect insertion failures
by Nick Martin 21 Oct '08

21 Oct '08

I recently discovered the boost multi_index library. It appears to be an incredible resource that I am really looking forward to using. Unfortunately, I have been frustrated by the documentation and unable to get much usable code written. The bulk of the information that has been helpful to me is in the examples. Branching out beyond what is specifically done in an example has proven to be difficult for me because of a lack of reference documentation. I am not an expert in reading templatized and type-defed code, so reading the headers themselves has been very time consuming. That led me to wonder if Doxygen-like documentation is available? For instance, the Asio library has a very nice reference available http://www.boost.org/doc/libs/1_36_0/doc/html/boost_asio/reference.html Looking at the TCP socket's connect method leads you here: http://www.boost.org/doc/libs/1_36_0/doc/html/boost_asio/reference/basic_st… Here I can see the parameters and return types and in general figure out how to use this class. Contrast that with multi_index. There doesn't appear to be comprehensive class reference documentation. I only figured out how to do simple tasks like inserting new items into the container by looking at the examples ( http://www.boost.org/doc/libs/1_36_0/libs/multi_index/example/basic.cpp) My specific question (which the examples don't seem to cover) is how to tell when insertion fails. What if the new item's unique key constraint fails? I have had many other, seemingly simple questions that I would hope could be answered in minutes or seconds that have turned into hours of trial and error and combing through example programs. What other resources are out there that I refer to in order to use this great library? Thanks, Nick

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How can I use unique_ptr with container and string in boost::interprocess?
by blp330 21 Oct '08

21 Oct '08

Hi, I have a complex data structure that wants to put into shared memory. In STL way it should be: list<tuple<string, string, map<string, string>>> As you can see, there are a lot of strings which will be put into shared memory. My current way to a string into a container is (I use list<string> as a example): typedef allocator<char, managed_windows_shared_memory::segment_manager> CharAllocator; typedef basic_string<char, std::char_traits<char>, CharAllocator> SharedMemoryString; typedef allocator<SharedMemoryString, managed_windows_shared_memory::segment_manager> PushValueAllocator; typedef list<PushValue, PushValueAllocator> PushQueue; In this way, I always must construct a SharedMemoryString first then put it into container: SharedMemoryString mStr(charAlloc); mStr = "some stirng..."; queue->push_back(mStr); In my understanding, this will cost twice memory allocations to store this string into shared memory. First time is mStr = "some string...", second time is that mStr is put into list container, then mStr's memory will be destructed after leaving the scope. This means if the string length is 1KB, my shared memory size at least must be 2 * 1KB + container overhead. This seems stupid because twice memory allocation and copy operation. So, I want to use unique_ptr to solve this problem. I try: typedef managed_unique_ptr<SharedMemoryString, managed_windows_shared_memory>::type StringUniquePtr; typedef allocator<StringUniquePtr, managed_windows_shared_memory::segment_manager> PushValueAllocator; typedef list<PushValue, PushValueAllocator> PushQueue; SharedMemoryString* mStr = new SharedMemoryString(charAlloc); *mStr = "some stirng..."; queue->push_back(StringUniquePtr(make_managed_unique_ptr(mStr, segment))); But it can't compile... :( I have no idea to make unique_ptr to work with string in container in boost::interprocess. How do I make this work? Thank you very much. -- View this message in context: http://www.nabble.com/How-can-I-use-unique_ptr-with-container-and-string-in… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] [graph] Newbie question: iterator shows vertices not added, always lo .. hi
by Cooprider, Nathan (US SSA) 21 Oct '08

21 Oct '08

Let me start off by saying I'm fairly new as well, but I won't let that stop me from putting my foot in my mouth: > Perhaps this behavior is dictated by my choices of data structures vecS? This would be my guess as well. Did you try using a different structure to see if the behavior changes? > Is the Boost book is (substantially?) better than using the online docs, > or is it just the same content on paper? I found the BGL book to be helpful to a certain degree. The walkthroughs and examples seem easier to follow, and the index and table of contents are helpful to have at one's fingertips. Unfortunately, it is a bit old and so some important features are not covered in the book at all (property bundles, subgraphs). For those you have to rely on the online documentation. Nathan

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Re: [Boost-users] Boost [Asio] Problem with POST Request and async_read
by anti00Zero 21 Oct '08

21 Oct '08

I Found the problem myself. The problem was transfer_at_least(1). I should write the hole content to the thhp server and after this I should read. With transfer_at_least(1) I wrote some content and want to read again from the server. But the server wants to recieve more content. >Hello. > >I've wrote a SSL Proxy and have a big problem. >I use a HTTP Client in bei Proxy to communicate with my HTTP Server. >HTTP Client and HTTP Server are localhost. A SSL Browser should call my local SSL Proxy and internal >a HTTP Client communicate with my HTTP Server. >If the SSL Brower sends a POST request to my proxy, I have a problem. > >This is my code: > >async_write(m_HTTPSocket, buffer(m_sSSLRequestBuffer), > transfer_at_least(1), > boost::bind(&CSession::HandleHTTPWriteRequest, this, placeholders::error)); > >void CSession::HandleHTTPWriteRequest(const error_code& error) >{ > if (!error) > { > async_read(m_HTTPSocket, buffer(m_HTTPResponse, >MAX_HTTPRESPONSE_BUFFER_LENGTH), > transfer_at_least(1), > boost::bind(&CSession::HandleHTTPReadResponse, this, placeholders::error, > placeholders::bytes_transferred)); > } > else if(error != error::eof) > { > SendErrorToSSL(error); > } >} > >void CSession::HandleHTTPReadResponse(const error_code& error, size_t iTransferredBytes) >{ > if(!error) > { > >The error is boost::asio::error::connection_aborted (10053 (WSAECONNABORTED)). If I don't use my >SSL Proxy the HTTP Browser works correct. > >I use Visual Studio 2005 with Boost 1.36 > >Thanks for help. -- GMX startet ShortView.de. Hier findest Du Leute mit Deinen Interessen! Jetzt dabei sein: http://www.shortview.de/wasistshortview.php?mc=sv_ext_mf@gmx

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error when using boost::thread_group
by Meng Yu 21 Oct '08

21 Oct '08

Dear all, I delted the boost folder carelessly,so I had to rebuild boost1_33_1. after i build bjam,I can compile ,run the thread.cpp in /boost_1_33_1/libs/thread/example/ but,when I compile and run the thread_group.cpp,I got these message: (gdb) bt #0 ~function0 (this=0xbffaacd0) at function_template.hpp:313 #1 0x080497c6 in main (argc=1, argv=0xbffaada4) at thread_group.cpp:17 (gdb) step Program received signal SIGSEGV, Segmentation fault. [Switching to Thread -1208067152 (LWP 29013)] 0x08049c57 in boost::detail::function::void_function_invoker0<void (*)(), void>::invoke (function_ptr= {obj_ptr = 0xb7fe53af, const_obj_ptr = 0xb7fe53af, func_ptr = 0xb7fe53af, data = "?}) at function_template.hpp:103 103 BOOST_FUNCTION_RETURN(f(BOOST_FUNCTION_ARGS)); and I got the same message when I use thread_group my system version :Linux version 2.6.9-5.EL ( bhcompile(a)decompose.build.redhat.com) (gcc version 3.4.3 20041212 (Red Hat 3.4.3-9.EL4)) boost:1.33.1

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[Proto] Extracting types of sub-expression in transform
by Ivan Godard 21 Oct '08

21 Oct '08

Eric Niebler wrote: Anybody who understands van Wijngaarden grammars can help by explaining them to me in small words. :-) A van Wijngaarden Grammar definition for some target language (Algol68 in this case) is essentially an executable program written in a text substitution language i.e. VWG itself. If a candidate program purportedly written in the language defined by the grammar (Algol68) is submitted to an interpreter for the VWG language definition and the result is the empty string then the submitted program is well formed according to the grammar. If the result of the exercise is not the empty string then the submitted program contains an error. The content of the left-over string (if one happens) is a clue about what was wrong in the submitted program, but practical compilers do not just run the submitted program against the grammar and tell you the result if any. Instead, the grammar is turned into a more conventional parser (automatically one hopes) so that actions can be performed as the grammar engine does the substitutions. These actions kick out the intermediate code for conventional middle- and back-ends. Note that such a parser is not pure syntax - because the VWG grammar embeds type and semantic constraints as well as syntactic ones, the actions can contain type and semantic behavior as well as conventional ASTs (Abstract Syntax Trees) - no separate bug-ridden semantic pass is needed. You can validly see the VWG definitional mechanism as merely writing a canonical compiler for the target language and then using that compiler for the definition. The advantage of writing this compiler in VWG instead of say C is the brevity and rigor of the grammar representation. However, VWG does not remove the fundamental ontological paradox involved in language definition and indeed involved in mathematics itself, where the problem of axioms remains since the Greeks. Ivan p.s. a tutorial for two-level Grammars is at http://homepages.cwi.nl/~steven/vw.html, but the surface syntax (of the Grammar) is somewhat different from that used in the Report. p.p.s. Also note that VWG is only a notational device for language definition; it still leaves the definition of the language itself up to the designer. Consequently designing a practical language remains. Thus it is trivial to write a VWG grammar that contains free non-terminals such that the syntax check of a candidate program in the defined language is equivalent to the halting problem. You thought gcc was slow? As a practical matter Algol68 was carefully defined to be LL(1) and compilable by a one-pass compiler with single-symbol lookahead, but that was the choice of the designers and not required by VWG. Would that C had been so designed! :-)

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[Boost.Python] Can't work out what an extractor does
by Kirit Sælensminde 21 Oct '08

21 Oct '08

I've been puzzling around about how to deal with converting my string type to/from Python. I've managed to get one part of the puzzle solved, but can't work out from the documentation what the other part is. The code I have so far is this: namespace { struct to_pystr { static PyObject *convert( const fostlib::string &s ) { std::wstring u( fostlib::coerce< std::wstring >( s ) ); return PyUnicode_FromWideChar( u.c_str(), u.length() ); } static PyTypeObject const* get_pytype() { return &PyUnicode_Type; } }; } BOOST_PYTHON_MODULE( crypto ) { using namespace boost::python; // fostlib::string fostlib::sha1( const fostlib::string& ) def( "sha1", fostlib::sha1 ); implicitly_convertible< fostlib::native_string, fostlib::string >(); to_python_converter< fostlib::string, to_pystr, false >(); } This works ok if the Python type is str, but it doesn't work for unicode strings: Boost.Python.ArgumentError: Python argument types in crypto.sha1(unicode) did not match C++ signature: sha1(fostlib::string) What I guess I need is some way to wrap the Python call PyUnicode_FromObject in order to construct my string type, probably from PyObject, but certainly from unicode. From the documentation at [1] it isn't at all clear what actually needs to be done -- I can't even tell from that what the function signature I need to code to is. I think this [2] is relevant, but can't work out in what way -- no mention is made of where the reference object comes from and nor is there an example of the implementation of a simple extractor concept -- the internal implementations of the ones given on the page are far from illuminating. [1]http://www.boost.org/doc/libs/1_36_0/libs/python/doc/v2/Extractor.html [2]http://www.boost.org/doc/libs/1_36_0/libs/python/doc/v2/lvalue_from_pytyp… It looks like there's some good emails linked from this page [3], but unfortunately the links to the Python list archives are broken. [3]http://www.boost.org/doc/libs/1_36_0/libs/python/doc/internals.html I did think about exposing my string class, but the __unicode__ operator doesn't seem to be supported. Adding it to the relevant Boost.Python headers doesn't appear to be enough to get it working and I don't think that is the right way to do this either. So, basically, I guess there ought to be a fairly simple way to add this sort of type conversion into the Boost.Python type registry, but it appears to be undocumented and I can't see anything for this in the examples or the tests in the library either. K

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