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by giridhar 12 Feb '18

12 Feb '18

Hi Boost https://goo.gl/wknrVF Giridhar

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[Graph] const safety in edge_list_impl::edge_iterator
by Hormoz Zarnani 11 Feb '18

11 Feb '18

Hello, I am wondering if there is a particular reason why the == and != operators for edge_list_impl::edge_iterator (defined in boost/graph/edge_list.hpp) are not marked const: // The implementation class for edge_list. template <class G, class EdgeIter, class T, class D> class edge_list_impl { public: ... struct edge_iterator { ... bool operator==(const self& x) { return _iter == x._iter; } bool operator!=(const self& x) { return _iter != x._iter; } EdgeIter _iter; edge_id _i; }; ... }; Also, it does not seem correct to have different const qualifiers for the operands of these operators (the above effectively says that the right operand is const, but the left operand may be changed). Thanks, Hormoz

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[Interprocess] Message queue hex names
by Davies, John 09 Feb '18

09 Feb '18

I have a handful of processes all communicating with message queues. Infrequently, if a process crashes and restarts, it can't connect to the previously created message queue and creates a new one with a long hex name. This is under Windows, but I'm seeing indications the same thing is happening under Linux. Or something very similar. Under what circumstances does it do this and if I can't stop it, can I at least detect that it happened? ________________________________ The information contained in this message may be confidential and legally protected under applicable law. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, forwarding, dissemination, or reproduction of this message is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message.

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coroutine2: pull/push_type ctors with r-value ref arg
by MM 09 Feb '18

09 Feb '18

Hello, push_type class have this ctor: template< typename Fn > push_type( Fn && fn) that moves the object fn, leaving it in a moved-from state. I have a vector V1<C> of class C instances that expose a public member operator: void operator()( coroutine::pull_type& source ); and I would like to construct a vector V2 of push_types, of same size, each element of V2 I construct by emplacing back a element from V1. I assume that leaves the objects in vector V1 in a moved-from state and not usable. Those objects C in V1 are needed for other purposes. Can I use those instances of C by accessing them where they've been moved to inside the elements of V2? If not, should I make a copy of V1 before populating V2? Thanks,

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Mailman upgrade
by Sys Admin - Boost 08 Feb '18

08 Feb '18

All, Per https://bugs.launchpad.net/mailman/+bug/1747209, Ciere staff will install 2.1.26 beginning 9-Feb-2018 04:00 UTC. While the maintenance is performed, incoming messages to the mailing lists for Boost will be temporarily blocked. This may result in “temporarily unable to deliver” messages received by senders if a message is delivered during the upgrade. The upgrade is expected to finish by 9-Feb-2018 05:00 UTC. Thanks, Brad Johnson Your Friendly Mailing List Admin

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[test] data driven test fails to compile when number of samples greater than 9
by Georgios Sermaidis 08 Feb '18

08 Feb '18

Hello, I am having trouble compiling a simple data driven test with 10 samples. I am using clang++ (Apple LLVM version 9.0.0 (clang-900.0.39.2))with C++14 flags enabled. According to this help page http://www.boost.org/doc/libs/1_66_0/libs/test/doc/html/boost_test/utf_refe… <http://www.boost.org/doc/libs/1_66_0/libs/test/doc/html/boost_test/utf_refe…> my compiler should have no problem dealing with number of samples greater than BOOST_TEST_DATASET_MAX_ARITY which is 10 by default. Even defining BOOST_TEST_DATASET_MAX_ARITY to 20 prior to including any headers still fails to compile with the following error: /usr/local/include/boost/test/data/test_case.hpp:182: error: no matching function for call to 'bind' boost::bind( &TestCase::template test_method<Arg...>, ^~~~~~~~~~~ Any ideas how to fix it? Here is the code: #define BOOST_TEST_MODULE dataset_example68 #define BOOST_TEST_DYN_LINK #include <boost/test/unit_test.hpp> #include <boost/test/data/test_case.hpp> #include <boost/test/data/monomorphic.hpp> #include <sstream> namespace bdata = boost::unit_test::data; BOOST_DATA_TEST_CASE( test1, bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ) ^ bdata::make( { 1, 2, 3, 5 } ), sample1, sample2, sample3, sample4, sample5, sample6, sample7, sample8, sample9, sample10) {} Thank you!

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[log] Setting log format with string
by Dirk Van Haerenborgh 07 Feb '18

07 Feb '18

Hi, I'm trying to simply set the log format of the sinks using a string. For example from a config file or just in code. Take for instance this simple line taken from the basic_example (https://github.com/boostorg/log/blob/master/example/basic_usage/ main.cpp) logging::add_console_log(std::clog, keywords::format = "%TimeStamp%: %Message%"); Whenever I add %Timestamp% to the log format, I keep getting this error: terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::gregorian::bad_year> >' what(): Year is out of valid range: 1400..10000 I can easily reproduce this by running these examples (without modification): https://github.com/boostorg/log/blob/master/example/basic_usage/ main.cpp https://github.com/boostorg/log/blob/master/example/ settings_file/main.cpp Am I doing something wrong? I have this same behaviour on both boost1.62 and boost1.65. The former as installed from the debian package manager. The latter was manually compiled... -Dirk

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[intrusive] list compatibility with existing application-defined intrusive lists
by Rahul Ramadas 05 Feb '18

05 Feb '18

Hi all, boost::intrusive lists can be easily customized to be compatible with an existing doubly-linked intrusive list implementation, such as the one used in the linux kernel (struct list_head). Indeed, I have been able to declare and use a boost::intrusive::list of my own with custom traits that uses struct list_head as the underlying representation, enabling me to simply use .end().pointed_node() to get access to the list head and pass it to legacy C code that expects a struct list_head*. However, I can't think of a way to achieve interoperability in the opposite direction. For example, I have an existing function (to be precise, a callback that I pass to legacy C code), that accepts a struct list_head* that is expected to contain a list of elements of a certain type. I want some way to "wrap" this raw pointer in a type-safe intrusive list type that I use as naturally as a boost::intrusive::list (iteration, modification, etc.). I see no way to achieve this. The way I see it, what I need is a boost::intrusive::list_ptr, a container that doesn't actually own the list head, but rather, points to a list head stored elsewhere. It would have the same interface as a list, allowing me to push_back, clear, etc., but behaves as a pointer when it comes to moves and copies. Additionally, there should also be a boost::intrusive::const_list_ptr, which will not allow me to modify the list, but still allows iteration and other non-modifying operations. Unless, of course, there are already existing mechanisms to achieve this. If anyone has any ideas, please let me know. Thanks.

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Boost Python with Continuum Anaconda?
by Stephen Gray 02 Feb '18

02 Feb '18

I'm trying to get started with Boost Python. I've built the Boost Python libraries and linked a simple test programme with embedded Python. My Python environments are managed by Anaconda. There are errors at runtime as detailed in this Stackoverflow posting: https://stackoverflow.com/questions/48552092/boost-python-embedding-error Can anyone please help me understand what the issue is and how to solve it? With thanks.

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asio: cancelling a named pipe client
by Stian Zeljko Vrba 01 Feb '18

01 Feb '18

I have a client which connects to a named pipe as follows: CreateFile(pipeName.c_str(),GENERIC_READ | GENERIC_WRITE, 0, nullptr, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, nullptr); The result of this call is assigned to a stream_handle. I want that io service shuts down orderly by run() returning due to running out of work. To achieve this, I post a lambda that effectively calls cancel() on the handle (hidden inside Kill()): _io.post([this]() { for (auto& w : _workers) w->Kill(); }); However, cancel() has no effect: the callback for async_read continues to return with error code of zero and data read from the pipe. For reference, this is the read call with its handler: template<typename T> void read(T& ioh, const asio::mutable_buffer& buf) { ioh.async_read_some(asio::buffer(buf), [this, self = shared_from_this()](const boost::system::error_code& ec, size_t sz) { if (ec == boost::system::errc::operation_canceled) return; if (ec) QUINE_THROW(Error(self->_ownersId, ec, "async_read_some")); self->ReadCompleted(sz); }); } ReadCompleted() processes the received data and loops by calling read() again. If I call close() the callback gets an error code and everything works out correctly, *except* that I get an error code [invalid handle] that gets logged as an error (though it's not). Am I correct in assuming that cancel() is an apparent noop in this case because of the race-condition where an I/O request completes successfully before cancel is invoked? If so, can you suggest a more elegant way (i.e., a way that doesn't induce a hard error) of exiting a loop as described here? Setting a member variable instead of calling cancel? Given the existence of the race-condition, what are use-cases for cancel? How to use it correctly, if at all possible? -- Stian

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