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[Graph] Computing reachable vertices on a graph
by Florian.PONROY＠fr.thalesgroup.com 20 Mar '09

20 Mar '09

Hi all, I need to get the list of all reachable vertices from a given vertex in a graph. I'm currently using the BFS algorithm to achieve that, which seems to fit well to my need. To understand its behavior, I simplified the http://www.boost.org/doc/libs/1_38_0/libs/graph/example/bfs.cpp example source code to this : typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::directedS > Graph; Graph G(1); boost::add_edge(0, 1, G); boost::add_edge(1, 2, G); boost::add_edge(2, 5, G); boost::add_edge(3, 2, G); boost::add_edge(4, 3, G); boost::add_edge(5, 3, G); typedef Graph::vertex_descriptor Vertex; std::vector<int> distances; distances.reserve(6); std::fill_n(&distances[0], 6, 0); // The source vertex Vertex s = *(boost::vertices(G).first); boost::breadth_first_search(G, s, boost::visitor(boost::make_bfs_visitor(boost::record_distances(&distances[0], boost::on_tree_edge())))); boost::print_graph(G); for (int i = 0; i < 6; i++) { std::cout << "Node " << i << " : "; if (distances[i] != 0) std::cout << "reachable, distance " << distances[i] << std::endl; else std::cout << "not reachable" << std::endl; } However, I encounter the following issue : in this example, vertices are numbered from 0 to 5. However, in my project, this is not the case, vertices could be numbered 5, 38, 42, 384... Using a vector in that case might not work as expected, a map<vertex, distance> would probably be better. I'm not quite familiar with BGL so far, maybe should I deal with a specific property map? Or using a visitor to record a vertex distance upon graph discovery? I'm a little bit lost, any help will be greatly appreciated! Thank you very much, -- Florian PONROY Thales Land & Joint France Tel. : +33(0)1 41 304 363 Fax : +33(0)1 41 303 560 Email : florian.ponroy(a)fr.thalesgroup.com

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Bug in boost.asio ssl::stream write_some read_some methods?
by Michael Peltonen 20 Mar '09

20 Mar '09

Hi, When I compile my program that uses synchronous ssl::stream methods read_some and write_some, the compiler complains about ambigious binds. I believe this is a bug in the boost.asio library. My code compiled and run fine on boost_1_36_0 in windows environment, but not with boost_1_37_0 or boost_1_38_0 on solaris SPARC 10 environment? Boost compiles fine without any errors on solaris, so I believe this is a new boost.asio bug that has been introduced in the newest two releases. I tried to confirm this by building boost_1_36_0 on my solaris machine, but could not get it to compile without errors. The error message: /usr/local/include/boost/asio/ssl/detail/openssl_stream_service.hpp: In member function `size_t boost::asio::ssl::detail::openssl_stream_service::read_some(boost::asio::ssl::detail::openssl_stream_service::impl_struct*&, Stream&, const Mutable_Buffers&, boost::system::error_code&) [with Stream = boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, Mutable_Buffers = boost::asio::mutable_buffers_1]': /usr/local/include/boost/asio/ssl/stream_service.hpp:149: instantiated from `size_t boost::asio::ssl::stream_service::read_some(boost::asio::ssl::detail::openssl_stream_service::impl_struct*&, Stream&, const MutableBufferSequence&, boost::system::error_code&) [with Stream = boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, MutableBufferSequence = boost::asio::mutable_buffers_1]' /usr/local/include/boost/asio/ssl/stream.hpp:397: instantiated from `size_t boost::asio::ssl::stream<Stream, Service>::read_some(const MutableBufferSequence&, boost::system::error_code&) [with MutableBufferSequence = boost::asio::mutable_buffers_1, Stream = boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, Service = boost::asio::ssl::stream_service]' program.cpp:691: instantiated from here /usr/local/include/boost/asio/ssl/detail/openssl_stream_service.hpp:416: error: call of overloaded `bind(int (*)(SSL*, void*, int), boost::arg<1>, void*, int)' is ambiguous /usr/local/include/boost/bind.hpp:1298: note: candidates are: boost::_bi::bind_t<R, F, typename boost::_bi::list_av_3<a1, A2, A3>::type> boost::bind(F, A1, A2, A3) [with R = int, F = int (*)(SSL*, void*, int), A1 = boost::arg<1>, A2 = void*, A3 = int] /usr/local/include/boost/bind/bind_cc.hpp:47: note: boost::_bi::bind_t<R, R (*)(B1, B2, B3), typename boost::_bi::list_av_3<a1, A2, A3>::type> boost::bind(R (*)(B1, B2, B3), A1, A2, A3) [with R = int, B1 = SSL*, B2 = void*, B3 = int, A1 = boost::arg<1>, A2 = void*, A3 = int] /usr/local/include/boost/asio/ssl/detail/openssl_stream_service.hpp: In member function `size_t boost::asio::ssl::detail::openssl_stream_service::write_some(boost::asio::ssl::detail::openssl_stream_service::impl_struct*&, Stream&, const Const_Buffers&, boost::system::error_code&) [with Stream = boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, Const_Buffers = boost::asio::const_buffers_1]': /usr/local/include/boost/asio/ssl/stream_service.hpp:132: instantiated from `size_t boost::asio::ssl::stream_service::write_some(boost::asio::ssl::detail::openssl_stream_service::impl_struct*&, Stream&, const ConstBufferSequence&, boost::system::error_code&) [with Stream = boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, ConstBufferSequence = boost::asio::const_buffers_1]' /usr/local/include/boost/asio/ssl/stream.hpp:320: instantiated from `size_t boost::asio::ssl::stream<Stream, Service>::write_some(const ConstBufferSequence&, boost::system::error_code&) [with ConstBufferSequence = boost::asio::const_buffers_1, Stream = boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, Service = boost::asio::ssl::stream_service]' program.cpp:704: instantiated from here /usr/local/include/boost/asio/ssl/detail/openssl_stream_service.hpp:342: error: call of overloaded `bind(int (*)(SSL*, const void*, int), boost::arg<1>, const void*, int)' is ambiguous /usr/local/include/boost/bind.hpp:1298: note: candidates are: boost::_bi::bind_t<R, F, typename boost::_bi::list_av_3<a1, A2, A3>::type> boost::bind(F, A1, A2, A3) [with R = int, F = int (*)(SSL*, const void*, int), A1 = boost::arg<1>, A2 = const void*, A3 = int] /usr/local/include/boost/bind/bind_cc.hpp:47: note: boost::_bi::bind_t<R, R (*)(B1, B2, B3), typename boost::_bi::list_av_3<a1, A2, A3>::type> boost::bind(R (*)(B1, B2, B3), A1, A2, A3) [with R = int, B1 = SSL*, B2 = const void*, B3 = int, A1 = boost::arg<1>, A2 = const void*, A3 = int] make: *** [program.o] Error 1 The code: boost::asio::io_service io_service; boost::asio::ip::tcp::acceptor acceptor(io_service, boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), 7722)); boost::asio::ssl::context context(io_service, boost::asio::ssl::context::sslv23); context.set_options( boost::asio::ssl::context::default_workarounds | boost::asio::ssl::context::no_sslv2 | boost::asio::ssl::context::single_dh_use); context.set_verify_mode( boost::asio::ssl::context::verify_peer | boost::asio::ssl::context::verify_fail_if_no_peer_cert); context.use_certificate_chain_file("server-public.pem"); context.use_private_key_file("server-private.pem", boost::asio::ssl::context::pem); context.use_tmp_dh_file("dh4096.pem"); context.load_verify_file("client-public.pem"); while(!exit) { for (;;) { std::string message; boost::array<char, 128> buf; boost::system::error_code error; boost::asio::ssl::stream<boost::asio::ip::tcp::socket> socket(io_service, context); acceptor.accept(socket.lowest_layer()); socket.handshake(boost::asio::ssl::stream_base::server); size_t len = socket.read_some(boost::asio::buffer(buf), error); if (error == boost::asio::error::eof) break; // Connection closed cleanly by peer. else if (error) throw boost::system::system_error(error); // Some other error. message.assign(buf.data(), len); if(message.compare("statistics") == 0) message = statistics_reply(); else message = error_reply(); boost::system::error_code ignored_error; socket.write_some(boost::asio::buffer(message), ignored_error); } } Regards, -Michael

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[mpl] for_each and set_c: misunderstanding or bug?
by Nevin ":-]" Liber 19 Mar '09

19 Mar '09

A friend of mine is having problems using setc with for_each. Given the following code: struct p { template<typename T> void operator()(T) const { std::cout << typeid(T).name() << std::endl; } }; typedef mpl::vector_c<int, 1, 2> vc; typedef mpl::set< mpl::integral_c<int, 1>, mpl::integral_c<int, 2> > si; typedef mpl::set_c<int, 1, 2> sc; int main() { mpl::for_each<vc>(p()); mpl::for_each<si>(p()); mpl::for_each<sc>(p()); // line does not compile } Under gcc 4.0.1 and Boost 1.38.0, we get the following error messages for the line in question: boost/mpl/next_prior.hpp:30: error: no type named 'base' in 'struct boost::mpl::set0_c<int>' boost/mpl/eval_if.hpp:38: error: no type named 'type' in 'struct boost::mpl::next<boost::mpl::s_iter<sc, boost::mpl::set0_c<int> > >' boost/mpl/for_each.hpp:78: error: 'value' is not a member of '<declaration error>' boost/mpl/for_each.hpp:78: error: 'execute' is not a member of '<declaration error>' Is this a misunderstanding on how to use for_each and set_c on our part? Regards, -- Nevin ":-)" Liber <mailto:nevin@eviloverlord.com> (847) 691-1404

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[version 1.38.0] Problems with dynamic linking to boost libraries
by Juan Antonio Farré Basurte 19 Mar '09

19 Mar '09

Hello, I'm using boost libraries in my research work and I need to link to graph and program options libraries. I've been working with version 1.37.0 without any problem. Now I updated to 1.38.0. I built the libraries in the same way and the same directories as 1.37.0 (on /usr/local). The compilation and dynamic linkage phase work, but when I run the program it complains with "file not found" on the shared library files. I've tried it in my home Fedora 10 installation and the Debian installation at my workplace and I have the same problem. For the moment, the only workaround I've found is explicitly linking the static versions of both libraries, while still dynamically linking to other libraries (like expat). Is there any problem in the installation phase of "./configure ; make install"? What can I do? Thanks in advance.

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Boost Serialization - Base Classes (very confused)
by Adrien Guillon 19 Mar '09

19 Mar '09

Hi all, I don't understand why the following code does not work. I get an unregistered class exception. AJ #include <boost/serialization/serialization.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/export.hpp> #include <string> #include <sstream> #include <iostream> namespace pbb { // BEGIN NAMESPACE pbb namespace internal { // BEGIN NAMESPACE internal /** * The base class for all requests to be made of a server. */ class server_request { friend class boost::serialization::access; public: virtual ~server_request(); virtual std::string description() = 0; private: template <typename Archive> void serialize(Archive& ar, const unsigned int version) { } }; class hello_request : public server_request { friend class boost::serialization::access; public: virtual ~hello_request(); virtual std::string description(); private: template <typename Archive> void serialize(Archive& ar, const unsigned int version) { ar & boost::serialization::base_object<server_request>(*this); } }; } // END NAMESPACE internal } // END NAMESPACE pbb namespace pbb { // BEGIN NAMESPACE pbb namespace internal { // BEGIN NAMESPACE internal server_request::~server_request() { } hello_request::~hello_request() { } std::string hello_request::description() { return "HELLO REQUEST"; } } // END NAMESPACE internal } // END NAMESPACE pbb BOOST_CLASS_EXPORT(pbb::internal::server_request); BOOST_CLASS_EXPORT(pbb::internal::hello_request); void msave(const pbb::internal::server_request& request, boost::archive::text_oarchive& o) { o << request; } pbb::internal::server_request* mload(boost::archive::text_iarchive& in) { pbb::internal::server_request* r; in >> r; return r; } int main() { // Create a string stream for I/O std::stringstream stream; pbb::internal::server_request* request = new pbb::internal::hello_request(); // Write a server request { boost::archive::text_oarchive out_archive(stream); msave(*request, out_archive); } // Read a server request pbb::internal::server_request* incoming_request; { boost::archive::text_iarchive in_archive(stream); incoming_request = mload(in_archive); } std::cout << incoming_request->description() << std::endl; }

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[asio] Problem with async_read/async_read_some not reacting to incoming data
by Stig Sandø 19 Mar '09

19 Mar '09

Hei, We're rewriting a client with boost asio but have run into some problems when stresstesting the client. The client is fetching textual and graphics from a server with one connection that is open at all time. When the client is getting large amounts of graphics data it will after awhile suddenly stop receiving data, and eventually it will hit our timeouts and the last call sent is an async_read/async_read_some. We are keeping the server well-fed with requests so there should be graphics forthcoming without pause. The problem has been seen on win32, linux and darwin when testing on a gigabit net fetching raw 1080i graphics (4M for each field), and is most frequent on darwin. This is naturally an absolute show-stopper for us. So we are a bit loss what is going wrong and why async_read/async_read_some stops reacting in the middle of the fetch-queue, despite wireshark showing that the data is incoming. When using compression on the data the problem is harder to reproduce, which might suggest a race-condition somewhere. But our code is just using a single thread for io_service and all async-communication is triggered from this io-thread which has a work-object to keep the io_service spinning. We're also making sure there is at most one async_read and one async_write in effect at a time, roughly similar to the chat_client sample. Has anyone seen something similar or have any input on how best to figure out what goes wrong? Are there invariants that says you cannot read and write at the same time? Some symptoms are the same in each test. When we get the last image from the socket the buffersize is zero afterwards, and the next async_read request is to transfer_at_least(1). The async_read never calls the handler for completion of this byte, so Nagle would have kicked in. It is also fairly hard to strip down to a small example using a mock server. I have included some stripped down code below in case that might be helpful spotting something that we cant see. Cheers, Stig Stacktrace during timeout of the asio-thread: (gdb) bt #0 0x91302f66 in kevent () #1 0x003e8010 in boost::asio::detail::kqueue_reactor<false>::run () #2 0x0045f70a in boost::asio::detail::task_io_service<boost::asio::detail::kqueue_reactor<false> >::do_one () #3 0x0045f8c3 in boost::asio::detail::task_io_service<boost::asio::detail::kqueue_reactor<false> >::run () #4 0x0045f972 in boost::asio::io_service::run () #5 0x003f8bbc in vcl::connection_pool::implementation::run () #6 0x003fa2fa in boost::_mfi::mf0<void, vcl::connection_pool::implementation>::operator() () #7 0x003fa356 in boost::_bi::list1<boost::_bi::value<vcl::connection_pool::implementation*> >::operator()<boost::_mfi::mf0<void, vcl::connection_pool::implementation>, boost::_bi::list0> () #8 0x003fa399 in boost::_bi::bind_t<void, boost::_mfi::mf0<void, vcl::connection_pool::implementation>, boost::_bi::list1<boost::_bi::value<vcl::connection_pool::implementation*> > >::operator() () #9 0x003fa62e in boost::detail::thread_data<boost::_bi::bind_t<void, boost::_mfi::mf0<void, vcl::connection_pool::implementation>, boost::_bi::list1<boost::_bi::value<vcl::connection_pool::implementation*> > > >::run () #10 0x003b97ce in thread_proxy () #11 0x913036f5 in _pthread_start () #12 0x913035b2 in thread_start () The connection headerfile: #ifndef VCL_ASIO_CONNECTION_HPP #define VCL_ASIO_CONNECTION_HPP #include <vcl/connection.hpp> #include <queue> #include <boost/asio.hpp> #include <boost/thread.hpp> #include <boost/enable_shared_from_this.hpp> namespace soul { struct logger_base; typedef boost::shared_ptr<logger_base> logger; } using boost::asio::ip::tcp; namespace vcl { class connection_manager; class dispatcher; class protocol; class response; typedef boost::shared_ptr<connection_manager> connection_manager_ptr; typedef boost::weak_ptr<connection_manager> connection_manager_wptr; typedef boost::shared_ptr<dispatcher> dispatcher_ptr; typedef boost::shared_ptr<protocol> protocol_ptr; typedef boost::weak_ptr<protocol> protocol_wptr; typedef boost::shared_ptr<response> response_ptr; typedef std::queue<request_ptr> req_queue; enum read_status { rs_no_valid_data, rs_read_one_block, rs_error_occured }; class asio_connection : public connection, public boost::enable_shared_from_this<asio_connection> { public: asio_connection(const soul::logger &logger, boost::asio::io_service& io_service, connection_manager_wptr cmgr, const dispatcher_ptr &disp, const vbl::host_repr_ptr &host, const protocol_ptr &cp); virtual ~asio_connection(); void handle_resolve(const boost::system::error_code& error, tcp::resolver::iterator endpoint_iterator); void handle_connect(const boost::system::error_code& error, tcp::resolver::iterator endpoint_iterator); virtual void lose_connection(); virtual void start_connecting(); virtual vbl::host_repr_ptr get_host(); virtual bool send(const request_ptr &req); static connection_ptr connect(const std::string &host, unsigned short port, const protocol_ptr &cp); private: void handle_write_request(const boost::system::error_code& error); unsigned handle_capture_request(); read_status handle_text_request(); read_status handle_icon_request(unsigned &next_amount); void start_reading(unsigned bytes=1); void handle_read_info(const boost::system::error_code& error, std::size_t tf); read_status _handle_read_info(unsigned &next_amount); void io_send(const request_ptr &req); bool io_dispatch_response(response_ptr myresponse); bool io_dispatch_error(const boost::system::error_code& error); std::string prepared_request(const request_ptr &msg) const; private: soul::logger local_logger; boost::asio::io_service& m_io_service; connection_manager_wptr m_manager; dispatcher_ptr m_dispatcher; tcp::socket m_socket; vbl::host_repr_ptr m_host; tcp::resolver::iterator m_host_iterator; protocol_wptr wcp; req_queue outgoing_requests; req_queue incoming_requests; boost::asio::streambuf inbuffer; request_ptr currently_reading; }; } #endif /* VCL_ASIO_CONNECTION_HPP */ And the stripped down communication-part of the connection object: #include "connection.hpp" #include "../logging.hpp" #include "../internal_response.hpp" #include <vcl/protocol.hpp> #include <vcl/request.hpp> #include "../manager.hpp" #include <vbl/host.hpp> #include <vbl/exceptions.hpp> #include <vcl/callback.hpp> #include <vcl/dispatcher.hpp> #include <boost/bind.hpp> namespace vcl { asio_connection::asio_connection(const soul::logger &logger, boost::asio::io_service& io_service, connection_manager_wptr cmgr, const dispatcher_ptr &disp, const vbl::host_repr_ptr &host, const protocol_ptr &cp) : local_logger(logger), m_io_service(io_service), m_manager(cmgr), m_dispatcher(disp), m_socket(io_service), m_host(host), wcp(cp) { } asio_connection::~asio_connection() { } void asio_connection::start_connecting() { tcp::resolver resolver(m_io_service); tcp::resolver::query query(m_host->get_hostname(), m_host->get_port_as_string()); boost::system::error_code ec; m_host_iterator = resolver.resolve(query, ec); handle_resolve(ec, m_host_iterator); } void asio_connection::handle_resolve(const boost::system::error_code& error, tcp::resolver::iterator endpoint_iterator) { // THIS CAN BE ANY THREAD if (!error) { tcp::endpoint endpoint = *endpoint_iterator; m_socket.async_connect(endpoint, boost::bind(&asio_connection::handle_connect, shared_from_this(), boost::asio::placeholders::error, ++m_host_iterator)); } else { m_io_service.post(boost::bind(&asio_connection::io_dispatch_error, shared_from_this(),error)); } } void asio_connection::handle_connect(const boost::system::error_code& error, tcp::resolver::iterator endpoint_iterator) { if (!error) { if (protocol_ptr p = wcp.lock()) { p->set_connection(shared_from_this()); m_dispatcher->dispatch(make_callback("connection made", boost::bind(&protocol::connection_made, p))); } // Now we start reading start_reading(); } else { io_dispatch_error(error); lose_connection(); } } bool asio_connection::io_dispatch_error(const boost::system::error_code& error) { if (protocol_ptr p = wcp.lock()) { m_dispatcher->dispatch(make_callback("Error occured", boost::bind(&protocol::error, p, error))); return true; } else { return false; } } void asio_connection::lose_connection() { /* vaious cleanup */ } void asio_connection::io_send(const request_ptr &msg) { // if the request expects an answer, push it in the incoming requests queu if (msg->get_type() != noreply_request) { incoming_requests.push(msg); } bool write_in_progress = !outgoing_requests.empty(); outgoing_requests.push(msg); if (!write_in_progress) { std::string data(prepared_request(outgoing_requests.front())); boost::asio::async_write(m_socket, boost::asio::buffer(data.data(), data.size()), boost::bind(&asio_connection::handle_write_request, shared_from_this(), boost::asio::placeholders::error)); } } void asio_connection::handle_write_request(const boost::system::error_code& error) { if (!error) { outgoing_requests.pop(); if (!outgoing_requests.empty()) { std::string data(prepared_request(outgoing_requests.front())); boost::asio::async_write(m_socket, boost::asio::buffer(data.data(), data.size()), boost::bind(&asio_connection::handle_write_request, shared_from_this(), boost::asio::placeholders::error)); } } else { lose_connection(); } } bool asio_connection::send(const request_ptr &msg) { if (!msg.get()) return false; // make sure we do the real stuff on the io-thread m_io_service.post(boost::bind(&asio_connection::io_send, shared_from_this(), msg)); return true; } void asio_connection::start_reading(unsigned bytes) { boost::asio::async_read(m_socket, inbuffer, boost::asio::transfer_at_least(bytes), boost::bind(&asio_connection::handle_read_info, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); } bool asio_connection::io_dispatch_response(response_ptr myresponse) { if (protocol_ptr p = wcp.lock()) { // make a callback and see what happens m_dispatcher->dispatch(make_callback("response received", boost::bind(&protocol::dispatch_response, p, myresponse))); return true; } else { return false; } } void asio_connection::handle_read_info(const boost::system::error_code& error, std::size_t tf) { if (!error) { unsigned next_amount = 0; read_status rs = _handle_read_info(next_amount); while (rs == rs_read_one_block) rs = _handle_read_info(next_amount); if (next_amount < 2) next_amount = 1; start_reading(next_amount); } else if (error.value() == boost::system::errc::operation_canceled) { // ignore this error for now, resolve it later lose_connection(); } else { lose_connection(); } } }

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range transformed -adaptor incompatible with lambda functions
by Sandeep Gupta 19 Mar '09

19 Mar '09

Hi, I would be nice if range-transformed worked with lambda functions. Is this an intended behaviour. To illustrate the following two statements fail for_each(myvec|boost::adaptors::transformed(arg1+mask), std::cout<<arg1<<' '); for_each(myvec|boost::adaptors::transformed(boost::lambda::_1 + mask), std::cout<<boost::lambda::_1<<' '); But this is fine: for_each(myvec|boost::adaptors::transformed(double_int()), std::cout<<boost::lambda::_1<<' '); where double_int hand created function object with result_type declaration. Thanks sandeep

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Re: [Boost-users] share_ptr reset() question
by 张亚霏 19 Mar '09

19 Mar '09

of cource, no memory leak. check out the source code of method 'reset'. there is a little trick help release the memory, which is similar with Effective STL: item 17: Use "swap trick" to trim excess capacity good luck ------------------ Original ------------------ From: "Ben"<befung(a)gmail.com>; Date: Thu, Mar 19, 2009 08:28 AM To: "boost-users"<boost-users(a)lists.boost.org>; Subject: [Boost-users] share_ptr reset() question Hello, Consider the following: void createSharePtr( boost::shared_ptr<int> value) { value.reset( new int(100)); } main() { boost::shared_ptr<int> y( new int(0)); createSharePtr( y); }; Question: Does the function createSharePtr() cause memory leak? Thanks, Ben _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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share_ptr reset() question
by Ben 19 Mar '09

19 Mar '09

Hello, Consider the following: void createSharePtr( boost::shared_ptr<int> value) { value.reset( new int(100)); } main() { boost::shared_ptr<int> y( new int(0)); createSharePtr( y); }; Question: Does the function createSharePtr() cause memory leak? Thanks, Ben

2 1

Re: [Boost-users] [graph] Convert bidirectional graphs into directed graphs
by Juan Antonio Farré Basurte 19 Mar '09

19 Mar '09

>> I need to convert any bidirectional graph into an >> adjacency_list<vecS,vecS,directedS>, >> but looks like the copy constructor cannot handle it (needs the same type in input). >> I don't see any simple way to convert any directed graph into an adjacency_list<vecS,vecS,directedS>. >> Is there any more-or-less-simple way to do it that I don't know? May be there is a way to copy graphs constrained not by the concrete type of the graph, >> but only, may be, on graph concepts? >> Thanks, > > There's no direct conversion between *any* bidirectional graph and a directed adjancency_list. If you're talking about any bidirectional adjacency list and a directed one, you shouldn't actually need to convert them. > > As an alternative, you could use copy_graph. > I need to do a copy of the graph before writing it into graphml or graphviz as a workaround for the problem I reported with subject [graph] Looks like there is a bug in some graph-writing function , which in my second message with the same subject I clarified the problem was related with creating dynamic_properties from bundled properties. It doesn't work with const graphs and I don't trust just performing a const_cast. I want to make sure that the input graph to my graph-writing functions is not modified at all. One solution would be just to do Graph *copy=new Graph(graph); where Graph is the graph-type template parameter, but this would require Graph to model Assignable, and I don't want to impose that. Also, copying the graph into a directed (not bidirectional) adjacency_list will save memory. copy_graph is perfect for my needs, as graph-writing boost functions already require the graph to model VertexListGraph (and, in general, the code I'm developing too). Sorry for not remembering about copy_graph and thank you very much :) Juan

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