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[lambda] Making my expression less complicated
by Peter Barker 05 Sep '08

05 Sep '08

Hello, In my test program below, I have a container of columns and want to output the column headers into a string separated by a tab. The lambda expression is looking fairly complicated so I wonder if it could be made simpler or if there's any other algorithm I should've used to put a separator between the elements? Regards, Pete #include <algorithm> #include <iostream> #include <string> #include <vector> #include <boost/lambda/bind.hpp> #include <boost/lambda/lambda.hpp> #include <boost/lambda/if.hpp> class Column { public: explicit Column(const std::string& str) : str_(str) {} const std::string& getColumnText() const {return str_;} private: std::string str_; }; int main() { using namespace boost::lambda; using boost::lambda::_1; std::vector<Column> cols; cols.push_back(Column("Fred")); cols.push_back(Column("Jim")); cols.push_back(Column("Harry")); const std::size_t numCols = static_cast<size_t>(cols.size()); const char fieldSeparator = '\t'; std::string outputText; std::size_t i = 1; var_type<std::size_t>::type iV(var(i)); std::for_each(cols.begin(),cols.end(), ( var(outputText) += bind(&Column::getColumnText,_1), if_then(iV < constant(numCols),var(outputText) += constant(fieldSeparator)), ++iV ) ); std::cout << '[' << outputText << ']'; }

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graph all pair shortest path problem
by Nicolas Heine 05 Sep '08

05 Sep '08

Hi *, I have a question about the All Pair Shortest Path (Johnson) algorithm. Here is my code: #include <boost/config.hpp> #include <fstream> #include <iostream> #include <iomanip> #include <vector> #include <boost/property_map.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/johnson_all_pairs_shortest.hpp> int main() { using namespace boost; typedef property<vertex_index_t, int, property<vertex_name_t, std::string> > VertexProperty; typedef property<edge_weight_t, int, property<edge_weight2_t, int> > EdgeProperty; typedef property<graph_name_t, std::string> GraphProperty; //adjacency_list<OutEdgeList, VertexList, Directed, // VertexProperties, EdgeProperties, // GraphProperties, EdgeList> typedef adjacency_list<listS, listS, undirectedS, VertexProperty, EdgeProperty, GraphProperty> Graph; boost::graph_traits<Graph>::vertex_descriptor u, v, w, first, second; int N = 10; Graph g; first = add_vertex(g); put(vertex_index, g, first, num_vertices(g)); second = add_vertex(g); put(vertex_index, g, second, num_vertices(g)); add_edge(first, second, g); u = first; v = second; for (int i = 2; i < N; i++) { w = add_vertex(g); put(vertex_index, g, w, i + 1); add_edge(u, w, g); add_edge(v, w, g); u = v; v = w; } add_edge(u, first, g); add_edge(v, second, g), add_edge(v, first, g); std::cout << "Finished to build Graph" << std::endl; //set weights to 1 typedef graph_traits<Graph>::edge_iterator EdgeIterator; EdgeIterator ei, edge_end; for ( boost::tie(ei, edge_end) = edges(g); ei != edge_end; ++ei){ put(edge_weight, g, *ei, 1); } std::vector<int> d(N, (std::numeric_limits<int>::max)()); int D[N][N]; johnson_all_pairs_shortest_paths(g, D, distance_map(&d[0])); std::cout << " "; for (int k = 0; k < N; ++k) std::cout << std::setw(5) << k; std::cout << std::endl; for (int i = 0; i < N; ++i) { std::cout << i << " -> "; for (int j = 0; j < N; ++j) { if (D[i][j] > 20 || D[i][j] < -20) std::cout << std::setw(5) << "inf"; else std::cout << std::setw(5) << D[i][j]; } std::cout << std::endl; } return 0; } When I compile I get the error: ../src/BGLTest.cpp: In function 'int main()': ../src/BGLTest.cpp:73: error: no matching function for call to 'johnson_all_pairs_shortest_paths(main()::Graph&, int [(((long unsigned int)(((int)N) - 1)) + 1u)][(((long unsigned int)(((int)N) - 1)) + 1u)], boost::bgl_named_params<int*, boost::vertex_distance_t, boost::no_property>)' What does that mean? I want to use the Johnson algorithm with a listS = Vertexlist and listS = Egelist. With listS, vecS as in your example it works fine. What can I do? Thanks in advance, Nico

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Closures emulation made easy
by Alexander Gutenev 05 Sep '08

05 Sep '08

Hi. Here's a trick. Use the idea of Boost.ScopeExit. But don't implement capturing of variables like in Boost.ScopeExit - use Boost.Bind which does it. Have easy to write and debug closure body - don't spend too much time on making Boost.Lamda work. And a compact implementation with very small proprocessor overhead, compared to Boost.ScopeExit. // Implementation #define CONCATENATE_DIRECT(s1, s2) s1##s2 #define CONCATENATE(s1, s2) CONCATENATE_DIRECT(s1, s2) #define ANONYMOUS_VARIABLE(str) CONCATENATE(str, __LINE__) #define LOCAL(R, P) \ typedef struct ANONYMOUS_VARIABLE(xg1) { \ typedef R(*F) P; static R body P { #define LOCAL_END(name) \ } } ANONYMOUS_VARIABLE(xg2); \ const ANONYMOUS_VARIABLE(xg2)::F name \ = ANONYMOUS_VARIABLE(xg2)::body; // Example #include <algorithm> int main() { LOCAL(bool, (int i, int j, bool reverse)) return reverse ? (j < i) : (i < j); LOCAL_END(myFcn) int a[] = { 2, 5, 1, 6 }; std::sort( a, a + sizeof(a)/sizeof(a[0]), boost::bind(myFcn, _1, _2, true)); }

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Cannot statically link to Boost.Filesystem
by Graham Bull 05 Sep '08

05 Sep '08

Hi all, I've got this really simple C++ program that's using the Boost.Filesystem library: #include <iostream> #include <boost/filesystem.hpp> int main() { boost::filesystem::path pathname = "/usr/local/bin"; std::cout << pathname.string() << std::endl; return 0; } It compiles fine, and I can get it to link to use the shared object: g++ -I/usr/local/include/boost-1_35 -o test test.cpp -lboost_filesystem-gcc42-mt-1_35 But I want to statically link instead. I've tried this and other similar combinations: g++ -I/usr/local/include/boost-1_35 -o test test.cpp -lboost_filesystem-gcc42-mt-s-1_35 -static -static-libgcc and I'm always getting these linker errors: /tmp/ccoiFv2v.o: In function `__static_initialization_and_destruction_0(int, int)': test.cpp:(.text+0x1dc): undefined reference to `boost::system::get_system_category()' test.cpp:(.text+0x1e6): undefined reference to `boost::system::get_posix_category()' test.cpp:(.text+0x1f0): undefined reference to `boost::system::get_posix_category()' test.cpp:(.text+0x1fa): undefined reference to `boost::system::get_system_category()' collect2: ld returned 1 exit status I've built Boost in full and have got these Boost.Filesystem libraries in /usr/local/lib: libboost_filesystem-gcc42-1_35.a libboost_filesystem-gcc42-1_35.so libboost_filesystem-gcc42-1_35.so.1.35.0 libboost_filesystem-gcc42.a libboost_filesystem-gcc42-d-1_35.a libboost_filesystem-gcc42-d-1_35.so libboost_filesystem-gcc42-d-1_35.so.1.35.0 libboost_filesystem-gcc42-d.a libboost_filesystem-gcc42-d.so libboost_filesystem-gcc42-mt-1_35.a libboost_filesystem-gcc42-mt-1_35.so libboost_filesystem-gcc42-mt-1_35.so.1.35.0 libboost_filesystem-gcc42-mt.a libboost_filesystem-gcc42-mt-d-1_35.a libboost_filesystem-gcc42-mt-d-1_35.so libboost_filesystem-gcc42-mt-d-1_35.so.1.35.0 libboost_filesystem-gcc42-mt-d.a libboost_filesystem-gcc42-mt-d.so libboost_filesystem-gcc42-mt-s-1_35.a libboost_filesystem-gcc42-mt-s.a libboost_filesystem-gcc42-mt-sd-1_35.a libboost_filesystem-gcc42-mt-sd.a libboost_filesystem-gcc42-mt.so libboost_filesystem-gcc42-s-1_35.a libboost_filesystem-gcc42-s.a libboost_filesystem-gcc42-sd-1_35.a libboost_filesystem-gcc42-sd.a libboost_filesystem-gcc42.so I hope someone can help me because I just can't see what I'm doing wrong! Graham

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[review] FSM Library review result
by Martin Vuille 05 Sep '08

05 Sep '08

This is a brief report of the results of the review of Andrey Semashev's Finite State Machines (FSM) library. I want to do justice to the discussions that took place, and will follow-up with a complete summary next week. In spite of a good amount of discussion and an extension of the review period, the number of reviews was smaller than I had hoped for. Nonetheless, I believe that the library received an adequate review and, based on the review comments and other discussions, the FSM library cannot be accepted into Boost at this time. A total of four reviews were submitted, as follows: Andrea Carbone: YES Phil Endecott: NO Jeff Flinn: NO Chris Knight: NO Darryl Green also submitted a mini-review, which did not include an explicit yes or no vote, but expressed doubt about whether the library should be accepted. On the positive side, several people noted that the goals of the library (simplicity and greater performance than Boost.StateCharts) were valid and that such a library was needed in some applications. I personally support this view. I would like to thank Andrey for his efforts in developing the library. I would like to encourage him to pursue the discussions that were begun during this review and perhaps try again with an updated submission. MV

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Re: [Boost-users] Format local time in W3C format (YYYY-MM-DDThh:mm:ss.sTZD) without providing the time zone myself?
by Paul Bormans 05 Sep '08

05 Sep '08

Does anyone have hints/tips for me to get properly formatted time zone (%Q) for local time "without" providing the time zone myself? _________________________________________________________________ Express yourself instantly with MSN Messenger! Download today it's FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/

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Boost.Multiindex namespace problem
by Axel 05 Sep '08

05 Sep '08

Hello I m using boost 1.35 and g++ v4.1.3 20070929 (Ubuntu 4.1.2-16ubuntu2) on ubuntu gutsy, I have a problem when using multindex namespaces. This compiles without problem : (this is in a class) using namespace boost::multi_index ; class myClass { public: struct foo { public: int getLocalDataId() ; } ; typedef hashed_unique<boost::multi_index::mem_fun<foo, int, &foo::getLocalDataId> > myIndex ; }; But the same code without the prefix "boost::multi_index" doesnt compile : typedef hashed_unique<mem_fun<foo, int, &foo::getLocalDataId> > myIndex ; I can obviously add the namespace before mem_fun, I just wonder why this compile error occurs. Thanks in advance.

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[Multi-index container] Why insertions into my Multi-index container are so slow?
by Angel Sunye 05 Sep '08

05 Sep '08

Hi everyone, I'm using a multi_index_container with 1 composite ordered_unique index and 1 hashed unique index. It have passed the unit tests perfectly, but when I have made the performance test, insertions into multi-index container went much slower than with a manual management. That grows exponentially with the number of insertions: 1000 insertions take 1.5 seconds, almost twice that without Multi-index library 10000 insertions take 160 seconds, thousands of times that without Multi-index library Below you can see my multi_index_container definition, and the insert calls that i have used. -----------------BEGIN CODE----------------- // TElementRec is a struct with its contructors // // Tags struct TMainIndexTag{}; struct TKeyIndexTag{}; typedef multi_index_container< TElementRec, indexed_by< ordered_unique< tag<TMainIndexTag>, composite_key< TElementRec, BOOST_MULTI_INDEX_MEMBER(TElementRec,PRIORITY_LEVEL,priority), BOOST_MULTI_INDEX_MEMBER(TElementRec,int,inputTimestamp), BOOST_MULTI_INDEX_MEMBER(TElementRec,TKey,key) > >, hashed_unique< tag<TKeyIndexTag>, BOOST_MULTI_INDEX_MEMBER(TElementRec,TKey,key) > > > TElementsMIContainer; // Using... TElementsMIContainer elMIContainer; elMIContainer.insert( elMIContainer.template get<TMainIndexTag>().end(), TElementRec( priority, key, content, inputTimestamp, 0 )); elMIContainer.insert( TElementRec( priority, key, content, inputTimestamp, 0 )); -----------------END CODE----------------- Is this boost implementation correct? Thanks a lot for your time Angel Suñe Marti

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boost::logging rolling files prefix
by Alejandro Martinez 05 Sep '08

05 Sep '08

Im trying to use rolling files, but im having a hard time formatting the names that the files should have. Like putting the date/time in it. The documentation has no examples and wasn't able to google it. Thanks for your time.

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[boost:regex]compiling error when building boost:regex with ICU
by gj_uestc 05 Sep '08

05 Sep '08

hi, while I tried to build all binaries of boost_1_35_0 with ICU, I only got 2 :libboost_regex-iw-mt-gd-1_35.lib and libboost_regex-iw-mt 1_35.lib,with the rest 6 are missing. I activated bjam like this: bjam --toolset=intel -with regex -sICU_PATH=/cygdrive/c/home/gejuan/ICU/icu4c-3_8_1-src/icu/source --build-type=complete -sHAVE_ICU=1 stage.and I got error message: Skipping build of: ./stage <build>no in common properties Skipping build of: ./stage <build>no in common properties Skipping build of: ./stage <build>no in common properties Skipping build of: ./stage <build>no in common properties Skipping build of: libs/regex/build/icucore <build>no in common properties Skipping build of: libs/regex/build/icuin <build>no in common properties Skipping build of: libs/regex/build/icudata <build>no in common properties C:/home/gejuan/boost_1_35_0/tools/build/v2/kernel\class.jam:93: in new *** argument error * rule object(searched-lib-target)(a)665.__init__ ( name : project : shared ? : search * : action ) * called with: ( icudata icui18n icuuc : object(project-target)@90 : true : libs/regex/build : object(null-action)@664 : : : : ) * extra argument icui18n C:/home/gejuan/boost_1_35_0/tools/build/v2/tools\builtin.jam:349:see definition of rule '__init__' being called C:/home/gejuan/boost_1_35_0/tools/build/v2/tools\builtin.jam:592: in object(searched-lib-generator)(a)6.run C:/home/gejuan/boost_1_35_0/tools/build/v2/build\generators.jam:859: in try-one-generator-really C:/home/gejuan/boost_1_35_0/tools/build/v2/build\generators.jam:920: in try-one-generator C:/home/gejuan/boost_1_35_0/tools/build/v2/build\generators.jam:1131: in construct-really what is the problem here?Did I miss something?

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