August 2003 - Boost-users - lists.preview.boost.org

Getting std::iterator_category from boost iterator adaptor
by Raoul Gough 13 Aug '03

13 Aug '03

I have a situation where I want to specialize a class template on the basis of iterator_category, but I don't see how to get one of the standard categories when passed a boost iterator adapter. Currently, std::iterator_traits<MyIter>::iterator_category is giving me: boost::iterator_tag<boost::writable_lvalue_iterator_tag , boost::random_access_traversal_tag> I need random_access_iterator_tag for the right specialization to happen. Is there any way to get the *standard* iterator category from a boost iterator? MyIter is boost::indirect_iterator<std::vector<int *>::iterator> compiler is gcc 3.2.3 (mingw special 20030504-1) BTW, isn't this non-standard iterator_category bound to cause problems? e.g. if I use std::distance (MyIter(), MyIter()), how does the compiler know that it should use the std::random_access_iterator_tag specialization of std::distance? -- Raoul Gough "Let there be one measure for wine throughout our kingdom, and one measure for ale, and one measure for corn" - Magna Carta

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[Spirit] file_iterator confusion
by Angus Leeming 13 Aug '03

13 Aug '03

Hello. I am just beginning to look at the spirit library, but am confused by the way file_iterator is working. Could anyone explain to me why this works: typedef spirit::file_iterator <char_t> iterator_t; iterator_t first(argv[1]); // check first is valid ... iterator_t last = first.make_end(); but this doesn't: typedef spirit::file_iterator <char_t> iterator_t; iterator_t first; iterator_t last; boost::tie(first, last) = open_file(argv[1]); // check first is valid ... Both codes compile, but only the first method results in the file being read. In the second instance, the correct number of chars are read, but only the first char is output (multiple times). The open_file function is simply: std::pair<iterator_t, iterator_t> open_file(char const * name) { iterator_t first(name); iterator_t last = first ? first.make_end() : iterator_t(); return std::make_pair(first, last); } Minimal sample code attached. My tests have been with boost 1.30.1. Changing the line #define FAILURE_MODE 1 toggles between the two cases. Best regards, Angus [Non-text portions of this message have been removed]

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Using BGL Graphviz with MSVC7
by Trevon Fuller 12 Aug '03

12 Aug '03

Is there documentation anywhere that explains how to build and link graphviz for MSVC .NET for use with the BOOST graph library? I am trying to compile the example ospf-example.cpp from the BOOST graph library in MSVC .NET. I am using BOOST 1.30.0. I built the graphviz library using bjam with the vc7 toolset. I am getting a compile error: c:\boost_1_30_0\boost\tuple\detail\tuple_basic_no_partial_spec.hpp(83): error C2679: binary '=' : no operator found which takes a right-hand operand of type 'const boost::detail::adj_list_gen<Graph,VertexListS,OutEdgeListS,DirectedS,VertexP roperty,EdgeProperty,GraphProperty,EdgeListS>::config::edge_iterator' (or there is no acceptable conversion) with [ Graph=boost::adjacency_list<boost::vecS,boost::vecS,boost::directedS,boost:: no_property,boost::property<boost::edge_weight_t,int,boost::no_property>,boo st::no_property,boost::listS>, VertexListS=boost::vecS, OutEdgeListS=boost::vecS, DirectedS=boost::directedS, VertexProperty=boost::no_property, EdgeProperty=boost::property<boost::edge_weight_t,int,boost::no_property>, GraphProperty=boost::no_property, EdgeListS=boost::listS ] I think this error is due to the fact that MSVC does not support partial template specialization. Also, when I comment out all of the code except for the first 3 lines of the main, I get the error : dijkstra_link_state_routing error result returned from 'cl.exe' ("dijkstra_link_state_routing" is the name of the solution that contains the file ospf-example.cpp). Any suggestions anyone could offer would be appreciated. Below is the code for ospf-example.cpp. It is the same as the code on the BOOST website. Thanks, Trevon Fuller //====================================================================== // Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee, // // This file is part of the Boost Graph Library // // You should have received a copy of the License Agreement for the // Boost Graph Library along with the software; see the file LICENSE. // If not, contact Office of Research, Indiana University, // Bloomington, IN 47405. // // Permission to modify the code and to distribute the code is // granted, provided the text of this NOTICE is retained, a notice if // the code was modified is included with the above COPYRIGHT NOTICE // and with the COPYRIGHT NOTICE in the LICENSE file, and that the // LICENSE file is distributed with the modified code. // // LICENSOR MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED. // By way of example, but not limitation, Licensor MAKES NO // REPRESENTATIONS OR WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY // PARTICULAR PURPOSE OR THAT THE USE OF THE LICENSED SOFTWARE COMPONENTS // OR DOCUMENTATION WILL NOT INFRINGE ANY PATENTS, COPYRIGHTS, TRADEMARKS // OR OTHER RIGHTS. //====================================================================== #include <fstream> // for file I/O #include <boost/graph/graphviz.hpp> // for read/write_graphviz() #include <boost/graph/dijkstra_shortest_paths.hpp> #include <boost/lexical_cast.hpp> int main() { using namespace boost; GraphvizDigraph g_dot; read_graphviz("figs/ospf-graph.dot", g_dot); typedef adjacency_list < vecS, vecS, directedS, no_property, property < edge_weight_t, int > > Graph; typedef graph_traits < Graph >::vertex_descriptor vertex_descriptor; Graph g(num_vertices(g_dot)); property_map < GraphvizDigraph, edge_attribute_t >::type edge_attr_map = get(edge_attribute, g_dot); graph_traits < GraphvizDigraph >::edge_iterator ei, ei_end; for (tie(ei, ei_end) = edges(g_dot); ei != ei_end; ++ei) { int weight = lexical_cast < int >(edge_attr_map[*ei]["label"]); property < edge_weight_t, int >edge_property(weight); add_edge(source(*ei, g_dot), target(*ei, g_dot), edge_property, g); } vertex_descriptor router_six; property_map < GraphvizDigraph, vertex_attribute_t >::type vertex_attr_map = get(vertex_attribute, g_dot); graph_traits < GraphvizDigraph >::vertex_iterator vi, vi_end; for (tie(vi, vi_end) = vertices(g_dot); vi != vi_end; ++vi) if ("RT6" == vertex_attr_map[*vi]["label"]) { router_six = *vi; break; } std::vector < vertex_descriptor > parent(num_vertices(g)); // All vertices start out as there own parent typedef graph_traits < Graph >::vertices_size_type size_type; for (size_type p = 0; p < num_vertices(g); ++p) parent[p] = p; #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300 std::vector<int> distance(num_vertices(g)); property_map<Graph, edge_weight_t>::type weightmap = get(edge_weight, g); property_map<Graph, vertex_index_t>::type indexmap = get(vertex_index, g); dijkstra_shortest_paths (g, router_six, &parent[0], &distance[0], weightmap, indexmap, std::less<int>(), closed_plus<int>(), std::numeric_limits<int>::max(), 0, default_dijkstra_visitor()); #else dijkstra_shortest_paths(g, router_six, predecessor_map(&parent[0])); #endif graph_traits < GraphvizDigraph >::edge_descriptor e; for (size_type i = 0; i < num_vertices(g); ++i) if (parent[i] != i) { e = edge(parent[i], i, g_dot).first; edge_attr_map[e]["color"] = "black"; } #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300 // VC++ can't handle write_graphviz :( { std::ofstream out("figs/ospf-sptree.dot"); out << "digraph loops {\n" << "size=\"3,3\"\n" << "ratio=\"fill\"\n" << "shape=\"box\"\n"; graph_traits<Graph>::vertex_iterator vi, vi_end; for (tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi) { out << *vi << "["; for (std::map<std::string,std::string>::iterator ai vertex_attr_map[*vi].begin(); ai != vertex_attr_map[*vi].end(); ++ai) { out << ai->first << "=" << ai->second; if (next(ai) != vertex_attr_map[*vi].end()) out << ", "; } out<< "]"; } for (tie(ei, ei_end) = edges(g); ei != ei_end; ++ei) { out << source(*ei, g) << " -> " << target(*ei, g) << "["; std::map<std::string,std::string>& attr_map = edge_attr_map[*ei]; for (std::map<std::string,std::string>::iterator eai attr_map.begin(); eai != attr_map.end(); ++eai) { out << eai->first << "=" << eai->second; if (next(eai) != attr_map.end()) out << ", "; } out<< "]"; } out << "}\n"; } #else graph_property < GraphvizDigraph, graph_edge_attribute_t >::type & graph_edge_attr_map = get_property(g_dot, graph_edge_attribute); graph_edge_attr_map["color"] = "grey"; write_graphviz("figs/ospf-sptree.dot" , g_dot); #endif std::ofstream rtable("routing-table.dat"); rtable << "Dest Next Hop Total Cost" << std::endl; for (tie(vi, vi_end) = vertices(g_dot); vi != vi_end; ++vi) if (parent[*vi] != *vi) { rtable << vertex_attr_map[*vi]["label"] << " "; vertex_descriptor v = *vi, child; int path_cost = 0; property_map < Graph, edge_weight_t >::type weight_map = get(edge_weight, g); do { path_cost += get(weight_map, edge(parent[v], v, g).first); child = v; v = parent[v]; } while (v != parent[v]); rtable << vertex_attr_map[child]["label"] << " "; rtable << path_cost << std::endl; } return EXIT_SUCCESS; }

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tuples: operator ==
by Konstantin M. Litvinenko 12 Aug '03

12 Aug '03

Hello, All! I can't compile this simple test: --------------------------------------------- #include <boost/tuple/tuple.hpp> #include <iostream> using namespace boost::tuples; using namespace std; int main() { typedef tuple<int, tuple<int, int> > Tuple; Tuple t1(1, make_tuple(1, 1)); Tuple t2(2, make_tuple(2, 2)); if (get<1>(t1) == get<1>(t2)) { cout << "equal"; } else { cout << " not equal"; } return 0; } ----------------------------------------- What am I doing wrong? Compilers: Borland Builder 6 (bcc32.exe 5.6.4) and VC7 With best regards, Konstantin M. Litvinenko aka Dark Angel.

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RE: [Boost-Users] boos::bind class member function
by Ioffe, Robert 12 Aug '03

12 Aug '03

Dirk, The following should not compile: for_each(v.begin(), v.end(), boost::bind(&myclass::print, _1)); since myclass::print actually takes two arguments and the first one is not the std::string, but the object of class myclass. So you should do something like this: myclass foo; for_each(v.begin(), v.end(), boost::bind(&myclass::print, foo, _1)); Have fun, Robert Ioffe -----Original Message----- From: dirk_griffioen [mailto:diddekio@yahoo.com] Sent: Tuesday, August 12, 2003 3:43 AM To: Boost-Users(a)yahoogroups.com Subject: [Boost-Users] boos::bind class member function Hi, I would like to use a for_each with a class member function. The for_each in myclass::do_print below does not compile. And I simply cant figure it out. I'm using vc7.1. //////////////////////////////// void print2(std::string s) { cout << s << '\n'; } class myclass { public: void print(std::string s); void do_print(); }; void myclass::print(std::string s) { cout << s << '\n'; } void myclass::do_print() { vector<std::string> v; v.push_back("a"); v.push_back("b"); v.push_back("c"); v.push_back("d"); for_each(v.begin(), v.end(), boost::bind(boost::type<void>(), &myclass::print, _1)); } ///////////////////////////////////////// nor will for_each(v.begin(), v.end(), boost::bind(&myclass::print, _1)); for_each(v.begin(), v.end(), boost::bind(print, _1)); whereas for_each(v.begin(), v.end(), boost::bind(print2, _1)); is ok It seems natural to do, but I cant get it. Dirk Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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BUG: _DLL used to define BOOST_SIGNALS_STATIC_LINK
by kaineumann2001 12 Aug '03

12 Aug '03

Under cl(MS)/icl(Intel) compiler hash-def '_DLL' denotes dynamic linking of the C runtime library. Therefore, signals library should not use this to determine linkage (I may wish to statically link the signals library, while dynamically linking c-runtime.) see file boost/signals/detail/signals_common.hpp where the following snippet is invalid: #if defined(_MSC_VER) && defined(_DLL) # define BOOST_SIGNALS_HAS_DLL_RUNTIME #endif #if defined(BOOST_SIGNALS_HAS_DLL_RUNTIME) && !defined (BOOST_SIGNALS_STATIC_LINK) # if defined(BOOST_SIGNALS_IN_LIBRARY_SOURCE) # define BOOST_SIGNALS_DECL __declspec(dllexport) # define BOOST_SIGNALS_BUILD_DLL # else # define BOOST_SIGNALS_DECL __declspec(dllimport) # endif #endif here BOOST_SIGNALS_DECL is defined as __declspec(dllimport) as a consequence of linking the c-runtime dynamically under cl/icl compilers. But that's not what I wanted - I wanted to link signals.lib statically. This same bug is in the regex library. In fact, anyone able to fix this, should search for _DLL in the BOOST headers. Cheers, Kai

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boos::bind class member function
by dirk_griffioen 12 Aug '03

12 Aug '03

Hi, I would like to use a for_each with a class member function. The for_each in myclass::do_print below does not compile. And I simply cant figure it out. I'm using vc7.1. //////////////////////////////// void print2(std::string s) { cout << s << '\n'; } class myclass { public: void print(std::string s); void do_print(); }; void myclass::print(std::string s) { cout << s << '\n'; } void myclass::do_print() { vector<std::string> v; v.push_back("a"); v.push_back("b"); v.push_back("c"); v.push_back("d"); for_each(v.begin(), v.end(), boost::bind(boost::type<void>(), &myclass::print, _1)); } ///////////////////////////////////////// nor will for_each(v.begin(), v.end(), boost::bind(&myclass::print, _1)); for_each(v.begin(), v.end(), boost::bind(print, _1)); whereas for_each(v.begin(), v.end(), boost::bind(print2, _1)); is ok It seems natural to do, but I cant get it. Dirk

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how to convert c++ objects to Python?
by cavok＠filibusta.crema.unimi.it 12 Aug '03

12 Aug '03

hi, i have a c++ function that returns a reference to a c++ object. i want to expose this function to Python making it return the Python version of the object. i'm using Boost.Python. i understood that i have to use to_python_converter but the body of the A_to_Python::convert function is mystery for me. Boost documentation's example solves the problem in a manner i'm not able to apply to my case. my A object is complex and i'd like to somewhat (re)use the class_ object. ---------------- CUT HERE ---------------- #include <boost/python.hpp> using namespace boost::python; struct A { void f() {} }; A a; struct A_to_Python { static PyObject* convert(const A& a) { // documentation says: // return PyObject_New(noddy_NoddyObject, &noddy_NoddyType); } }; A& get_A() { return a; } BOOST_PYTHON_MODULE(hello) { class_<A>("A") .def("f", &A::f) ; to_python_converter<A, A_to_Python>(); def("get_A", get_A, return_value_policy<reference_existing_object>()); } ---------------- CUT HERE ---------------- please, somebody enlighten me. many thanks domenico -----[ Domenico Andreoli, aka cavok --[ http://filibusta.crema.unimi.it/~cavok/gpgkey.asc ---[ 3A0F 2F80 F79C 678A 8936 4FEE 0677 9033 A20E BC50

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BGL write_graphviz and VertexList type
by Solomon Gibbs 12 Aug '03

12 Aug '03

Hello, I've been trying to use the write_graphviz function in BGL, and I've noticed that it appears to be sensitive to the type of VertexList used in the graph. adjacency_lists using a boost::vecS produce vertex indices in integer form like: graph G { 0[label="0"]; 1[label="1"]; 0--1 [label="2.8"]; } but the same code backed by boost::listS seems to not dereference completely: graph G { 0x80545f0[label="10"]; 0x8054608[label="11"]; 0x80545f0--0x8054608 [label="2.8"]; } dot doesn't like this. I notice that write_graphviz dereferences boost::graph_traits<Graph>::vertex_iterator to print the vertex. Are the listS and vecS *operators different somehow? The vector backed adjacency_list also seems to be automagically setting the vertex_index property to the actual index of the vertex in the storage vector instead of the value given in add_vertex(). My question is: Is this the expected behavior for these classes or some problem I've managed to create on my own? Thanks, Solomon

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boost::python - how to expose c++ instancess?
by cavok＠filibusta.crema.unimi.it 11 Aug '03

11 Aug '03

hi, i'd like to do something like this: -------------- CUT HERE -------------- #include <boost/python.hpp> using namespace boost::python; struct A { void f() { /* do something */ } }; A a; BOOST_PYTHON_MODULE(hello) { class_<A>("A") .def("f", &A::f) ; def_readwrite("a", a); } -------------- CUT HERE -------------- i don't see how to do it with boost. any hint for a poor newbie? thanks dom -----[ Domenico Andreoli, aka cavok --[ http://filibusta.crema.unimi.it/~cavok/gpgkey.asc ---[ 3A0F 2F80 F79C 678A 8936 4FEE 0677 9033 A20E BC50

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