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error: template argument for template type parameter must be a type template< class Allocator = std::allocator< none > >
by Phil Phil 05 Jul '24

05 Jul '24

Greetings, I try to port a c++ project to a new environment with clang++-17, libcxx 17 and std=c++17 for x64 Linux. Also, I switched form boost 1.65 to 1.84. Now I start getting errors in boost itself: /workspace/usr/include/boost/statechart/fifo_worker.hpp:55:45: error: template argument for template type parameter must be a type 55 | template< class Allocator = std::allocator< none > > As far as I know this has to do with deprecation of some variable type in allocator. Any ideas how I might fix this on short notice? Regards

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directory_iterator UNC path
by Lars Sunde 04 Jul '24

04 Jul '24

Hello, Using boost::filesystem::directory_iterator with an UNC path failed with Boost 1.84 and Windows 10. Did some research on this topic and found this bug report from 2022; https://github.com/boostorg/filesystem/issues/245 This issue contain a link to this fix; https://github.com/boostorg/filesystem/commit/9c9d127bddc2b72187c57f4933c49… When looking at boost 1.84 and 1.85 source code I cannot find the fix shown above. Please excuse my ignorance but what is the relationship between https://github.com/boostorg/filesystem and the sw released at https://www.boost.org<https://www.boost.org/> ? Kind regards, Lars [https://opengraph.githubassets.com/d5334b4df3942668241ead9dde0a136ddc1b0979…]<https://github.com/boostorg/filesystem> GitHub - boostorg/filesystem: Boost.org filesystem module<https://github.com/boostorg/filesystem> Boost.org filesystem module. Contribute to boostorg/filesystem development by creating an account on GitHub. github.com

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Re: [Boost-users] Windows binaries, etc
by Michael Powell 30 Jun '24

30 Jun '24

Hello, Been a minute since I last updated my Boost libraries. Curious what the condition of the binaries is, re: VS2022 C++ compiler compatibility, alignment with current lang standards, such as this? https://boost.teeks99.com/bin/1.85.0/ As far as integration goes, I just add include and library paths to my projects, and on from there. Already more or less familiar with that aspect. Cheers, best, Michael W. Powell

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boost-python - call c++ methods within another method with embedded Python ?
by Nicholas Yue 28 Jun '24

28 Jun '24

Hi I am trying to add an ability to allow for the calling of methods within a another method that is running an embedded python but I get an error saying "TypeError: No Python class registered for C++ class MyClass". #include <boost/python.hpp> class MyClass { public: MyClass() = default; void method1(); void method2(); void executePython(); }; #include <iostream> void MyClass::method1() { std::cout << "Method 1 called" << std::endl; } void MyClass::method2() { std::cout << "Method 2 called" << std::endl; } void MyClass::executePython() { try { Py_Initialize(); // Expose the current instance (self) to the embedded Python script boost::python::object main_namespace; main_namespace["self"] = boost::python::ptr(this); // Execute Python code that calls method1 and method2 on self boost::python::exec("self.method1()\nself.method2()", main_namespace); Py_Finalize(); } catch (boost::python::error_already_set&) { PyErr_Print(); } } int main() { MyClass mc; mc.executePython(); return 0; } -- Nicholas Yue https://www.linkedin.com/in/nicholasyue/

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Fwd: [beast] Trying to Integrate Chunked Encoding into server-sync Example
by Max D 29 May '24

29 May '24

Hi everyone, I'm trying to integrate the manual chunked encoding example [0] into the sync-server example [1] and have difficulties understanding a compiler error. I thought I might find some help in this mailing list. Here's my diff to the original example: @@ -151,6 +151,22 @@ handle_request( req.method() != http::verb::head) return send(bad_request("Unknown HTTP-method")); + if (req.target().find("/chunked") == 0) { + std::vector<uint8_t> data; + for (int i = 0; i < 10; i++) { + data.push_back(0x00); + } + net::const_buffer buf {data.data(), 10}; + + send.send_chunk_headers(); + + for (int i = 0; i < 3; i++) { + send.send_chunk(buf); + } + + send.send_last_chunk(); + } + // Request path must be absolute and not contain "..". if( req.target().empty() || req.target()[0] != '/' || @@ -243,6 +259,29 @@ struct send_lambda http::serializer<isRequest, Body, Fields> sr{msg}; http::write(stream_, sr, ec_); } + + void + send_chunk_headers() + { + http::response<http::empty_body> res {http::status::ok, 11}; + res.set(http::field::server, "Beast"); + res.chunked(true); + + http::response_serializer<http::empty_body> sr{res}; + http::write_header(stream_, sr); + } + + void + send_last_chunk() + { + http::write(stream_, http::make_chunk_last()); + } + + void + send_chunk(net::const_buffer buf) const + { + http::write(stream_, http::make_chunk(buf)); + } }; // Handles an HTTP server connection I'm passing a TCP socket as well as the result of http::make_chunk() with a net::const_buffer to http::write() which, if I understand correctly, is the same thing that is done in the example. However, I'm getting the following error when compiling: .../server-sync/src/beast.cpp: In instantiation of ‘void send_lambda<Stream>::send_chunk(boost::asio::const_buffer) const [with Stream = boost::asio::basic_stream_socket<boost::asio::ip::tcp>]’: .../server-sync/src/beast.cpp:164:28: required from ‘void handle_request(boost::beast::string_view, boost::beast::http::request<Body, boost::beast::http::basic_fields<Allocator> >&&, Send&&) [with B ody = boost::beast::http::basic_string_body<char>; Allocator = std::allocator<char>; Send = send_lambda<boost::asio::basic_stream_socket<boost::asio::ip::tcp> >&; boost::beast::string_view = boost::basic_string_view<char, std::char_traits< char> >; boost::beast::http::request<Body, boost::beast::http::basic_fields<Allocator> > = boost::beast::http::message<true, boost::beast::http::basic_string_body<char>, boost::beast::http::basic_fields<std::allocator<char> > >]’ .../server-sync/src/beast.cpp:313:57: required from here .../server-sync/src/beast.cpp:283:20: error: no matching function for call to ‘write(boost::asio::basic_stream_socket<boost::asio::ip::tcp>&, boost::beast::http::chunk_body<boost::asio::const_buffer>) ’ 283 | http::write(stream_, http::make_chunk(buf)); | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The same thing happens for the send_last_chunk() call. Why isn't the call to write() working? Did I misunderstand something in the example? I'm using boost 1.71 and am compiling with GCC 10.3.0. Let me know if you need any more details. Thanks in advance for any help Max --- [0] https://www.boost.org/doc/libs/1_71_0/libs/beast/doc/html/beast/using_http/… [1] https://www.boost.org/doc/libs/1_71_0/libs/beast/example/http/server/sync/h…

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boost::flyweights::intermodule_holder
by Foelsche, Peter 10 May '24

10 May '24

Dear All, Thanks for the boost library! Apparently the boost::flyweight::intermodule_holder on LINUX is creating shared memory objects, which by accident (crash?) can persist after the process having created them is already gone. As a result I ran into the following situation: I could not successfully run some code, as it attempted to create an already existing shared memory object created by another user. Would the following be a solution to this problem: Use a copy of the code of the static_holder inside another namespace as attached and compile one module with __INCLUDE_HOLDER__ defined and all the rest without this define? Peter

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Boost Graph - adjacency_list in_edge_iterator are only input_iterator_tag?
by Nic 10 May '24

10 May '24

Hi, Hopefully this is the right place for this. This with Boost 1.81.0 It looks like boost::adjacency_list's in_edge_iterator, out_edge_iterator, and for bidirectional graphs also edge_iterator all are only input iterators. This seems a bit restrictive, and is regardless of the type of EdgeList template parameter. For example, this code (which seems a relatively reasonable thing to want to do) doesn't work: https://godbolt.org/z/n3PdEYo49 It doesn't work because transform_view doesn't define iterator_category if the iterator is not at least a forward iterator (I'm a bit confused as to why that is, but that's not a boost-related thing). I did some digging and found out why the iterator is always an input iterator: The iterators are defined as following: template < class BaseIter, class VertexDescriptor, class EdgeDescriptor, class Difference > struct in_edge_iter : iterator_adaptor< in_edge_iter< BaseIter, VertexDescriptor, EdgeDescriptor, Difference >, BaseIter, EdgeDescriptor, use_default, EdgeDescriptor, Difference > { // .... }; EdgeDescriptor is passed in as the reference type, but it is not a reference so the iterator adaptor always chooses input_iterator_tag for the iterator_category. Does anyone know of a workaround, or know if this is the desired behavior for edge iterators? Am I missing something obvious here? Thank you very much, Nicolas Morales

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boost.asio: random_access_file, io_uring and thread safety
by Matwey V. Kornilov 30 Apr '24

30 Apr '24

Hello, random_access_file is backed by the io_uring kernel interface on Linux. However, It is still unclear from Boost.Asio documentation, whether simultaneous parallel async_write_at in-flight requests are permitted by Asio? The queue of simultaneous requests is natively supported by io_uring. Is it still true for Asio? Is it also safe to fire parallel async_write_at from different threads? -- With best regards, Matwey V. Kornilov

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Is there a buffered tcp stream in ASIO?
by accelerator0099 29 Apr '24

29 Apr '24

|Prepare a tcp server listening on [::]:23380, run the following code: #include <boost/asio.hpp> namespace io = boost::asio; using boost::system::system_error; int main() { try { io::io_context ctx; using io::ip::tcp; using io::buffer; tcp::socket s1(ctx); s1.connect(tcp::endpoint(io::ip::address_v4::loopback(), 23380)); for (size_t i{}; i != 10; ++i) io::write(s1, buffer("123", 3)); } catch (system_error& e) { return 1; } } strace says there are 10 syscalls: connect(6, {sa_family=AF_INET, sin_port=htons(23380), sin_addr=inet_addr("127.0.0.1")}, 16) = 0 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 sendto(6, "123", 3, MSG_NOSIGNAL, NULL, 0) = 3 If I use boost::asio::ip::tcp::iostream: #include <boost/asio.hpp> namespace io = boost::asio; using boost::system::system_error; int main() { try { io::io_context ctx; using io::ip::tcp; using io::buffer; tcp::iostream s1{ tcp::socket(ctx) }; auto& nl = s1.socket(); nl.connect(tcp::endpoint(io::ip::address_v4::loopback(), 23380)); for (size_t i{}; i != 10; ++i) s1.write("123", 3); s1.flush(); } catch (system_error& e) { return 1; } } It does not make sense, still 10 syscalls: connect(6, {sa_family=AF_INET, sin_port=htons(23380), sin_addr=inet_addr("127.0.0.1")}, 16) = 0 ioctl(6, FIONBIO, [1]) = 0 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="123", iov_len=3}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 3 Is there a stream in asio that could buffer the multiple and small pieces of data into one syscall? |

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Difference in regex_replace replacement format handling between Boost.Regex and std::regex
by Josué Andrade Gomes 22 Apr '24

22 Apr '24

There is a difference in how the replacement format string is handled by regex_replace in Boost.Regex and std::regex. Consider the following example: #include <iostream>#include <regex>#include <boost/regex.hpp> int main() { std::string s{"a:b:c"}; std::string rx{":"}; std::string r{"\\$&"}; // Using std::regex std::string result_std = std::regex_replace(s, std::regex(rx), r); std::cout << "std::regex result: " << result_std << std::endl; // Outputs "a\:b\:c" // Using Boost.Regex std::string result_boost = boost::regex_replace(s, boost::regex(rx), r); std::cout << "Boost.Regex result: " << result_boost << std::endl; // Outputs "a$&b$&c" return 0; } std::regex result: a\:b\:c Boost.Regex result: a$&b$&c Affects Boost.Regex 1.84. I didn’t try other versions. Tested with GCC 13.2, clang 18.10 , cl 19.39.33523 and results are the same. Not tested with other versions. https://github.com/boostorg/regex/issues/210

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