November 2017 - Boost-users - lists.preview.boost.org

[interprocess] Determine size of managed_shared_memory
by Kai Benndorf 12 Oct '19

12 Oct '19

Hi all, I want to create a managed_shared_memory in exactly the size I needed. Therefore I do something like this: size = sizeof( common_managed_shared_memory ); size += sizeof( MyClassInSharedMem ); managed_shared_memory segment(create_only, "name", size ); MyClassInSharedMem allocates itself some memory by segment->allocate(). I added this also to the size, but get a boost::interprocess::bad_alloc exception on allocating this additional memory. Are there some magic bytes I forgot to add? Many thanks in advance Kai

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boost::filtered_graph filtering on vertex color... if I only had a colormap
by Brian Davis 19 Jul '19

19 Jul '19

Lets say I have a graph g (of type graph_t) and a color map (boy I wish I had a colormap): typedef boost::property_map<graph_t, boost::vertex_color_t>::type color_map_t; or is it? auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::default_color_type>(indexmap); or maybe? auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::vertex_color_t>(indexmap); or possibly some goop found on the internet? boost::make_iterator_property_map(color_map.begin(), boost::get(boost::vertex_index, data_->g), color_map[0]) or other internet goop? typedef boost::property_map<GraphType, boost::vertex_color_t>::type color_map_t; color_map_t colorMap; boost::color_map(colorMap)) or other internet goop?? std::vector<int> colorMap(num_vertices(g), boost::white_color); so confused... (certainly not surprised why bgl is not a part of stl) Can someone help explain the various types and ways of specifying colormaps and the logic for each way and means? and a function (if I could get that far without VS syntax highlighter going bonkers and gobs of compiler errors.. you know the type): make_pretty(g, colormap ) which colors the graph colormap and a filter struct for boost::filtered_graph<Graph, EdgePredicate, VertexPredicate> (where I wonder why if I only want to filter vertices I have to set boost::keep_all for EdgePredicate... sigh... I know the answer... and also know how long it found me to find/figure out boost::keep_all - and if you are looking for boost::keep_all and found it here... your welcome ;-) ) and modifying (probably incorrectly) boost::filtered_graph example to: template <typename ColorMap> struct vertex_color_filter_eq { vertex_color_filter_eq() { } vertex_color_filter_eq(ColorMap colormap/*, boost::default_color_type c*/) : m_colormap(colormap)/*, m_c(c)*/ { } template <typename Vertex> bool operator()(const Vertex& v) const { return 0 < get(m_colormap, v); //return c < get(m_colormap, v); } ColorMap m_colormap; //boost::default_color_type m_c; }; auto indexmap = boost::get(boost::vertex_index, g); auto colors = boost::make_vector_property_map<boost::default_color_type>(indexmap); // some where here I would call make_pretty(g, colors) typedef property_map<graph_t, boost::vertex_color_t>::type ColorMap_t; vertex_color_filter<ColorMap_t> filter(colors); // boost::filtered_graph<graph_t, boost::keep_all, VertexPredicate> boost::filtered_graph<graph_t, boost::keep_all, vertex_color_filter> fg(g, filter); // Later say if I could get it compile and better if it compiled and worked I could move on and auto color = boost::red_color; typedef property_map<graph_t, boost::vertex_color_t>::type ColorMap_t; vertex_color_filter<ColorMap_t> filter(colors, color); boost::filtered_graph<graph_t, boost::keep_all, vertex_color_filter> fg(g, filter); Maybe if I color them yellow, I can then reach the wizard pull back the curtain and ask how to create a color map... If I only had a color map.

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Boost Unit Test: How to run only the enabled tests of a test suite?
by Maarten Anonymous 28 Dec '17

28 Dec '17

Hey, I'm looking for a way to only run the enabled unit tests of a tests suite. I have the following test suite: #define BOOST_TEST_MODULE decorator_predicate#include <boost/test/included/unit_test.hpp>namespace utf = boost::unit_test; BOOST_AUTO_TEST_SUITE(test_suite_1) BOOST_AUTO_TEST_CASE(bare_test){ BOOST_TEST(true);} BOOST_AUTO_TEST_CASE(enabled_test, * utf::enabled()){ BOOST_TEST(true);} BOOST_AUTO_TEST_CASE(disabled_test, * utf::disabled()){ BOOST_TEST(false);} BOOST_AUTO_TEST_SUITE_END() BOOST_AUTO_TEST_SUITE(test_suite_2) BOOST_AUTO_TEST_CASE(bare_test){ BOOST_TEST(true);} BOOST_AUTO_TEST_CASE(enabled_test, * utf::enabled()){ BOOST_TEST(true);} BOOST_AUTO_TEST_CASE(disabled_test, * utf::disabled()){ BOOST_TEST(false);} BOOST_AUTO_TEST_SUITE_END() Compilation and running: # Compile the test g++ predicate.cpp -o predicate # List all tests./predicate --list_content test_suite_1* bare_test* enabled_test* disabled_test test_suite_2* bare_test* enabled_test* disabled_test # Run the tests that are enabled by default./predicateRunning 4 test cases... *** No errors detected # Here, I would like to only run the enabled tests of test_suite_1.# Instead, all tests are run. Including the disabled../predicate -t test_suite_1Running 3 test cases... predicate.cpp(21): error: in "test_suite_1/disabled_test": check false has failed *** 1 failure is detected in the test module "decorator_predicate" How can I only run the enabled tests of tst_suite1? Only bare_test and enabled_test should be run. Thanks!

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[test] Set fixture for all tests
by Florian Lindner 28 Dec '17

28 Dec '17

Hello, can I set a fixture for the entire test tree, so that it is called before and after each test case? BOOST_FIXTURE_TEST_CASE does that for a test suite, but how can I apply it to all tests e.g. the master test suite? Thanks, Florian

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[iostreams] file_descriptor doesn't retry on EINTR
by David Roberts 30 Nov '17

30 Nov '17

Hi, I have found that the file_descriptor class in Boost.Iostreams does not retry on EINTR. The relevant code is in libs/iostreams/src/file_descriptor.cpp. A bug was raised for this 7 years ago: https://svn.boost.org/trac10/ticket/4913 <https://svn.boost.org/trac10/ticket/4913> There is a patch attached to that bug that makes the file_descriptor_impl::read method retry on EINTR. If something like this were implemented then something similar should also be done to retry in the file_descriptor_impl::write method. I could have a go at submitting a PR to make both the read and write methods retry if interrupted. But before I do this, is there any other history I should be aware of, like a good reason why EINTR is not currently handled? Many thanks, David

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boost::asio::buffer bug with string literal
by Martijn Otto 29 Nov '17

29 Nov '17

When using boost::asio::buffer with a string literal the terminating null character is included in the buffer size, leading to bugs like accidentally sending out a null character. We could fix this by adding something like this to buffer.hpp: /// Create a new non-modifiable buffer that represents the given character array. /** * @returns A const_buffer value equivalent to: * @code const_buffer( * static_cast<const void*>(data), * (N - 1) * sizeof(char)); @endcode */ template <std::size_t N> inline BOOST_ASIO_CONST_BUFFER buffer( const char (&data)[N]) BOOST_ASIO_NOEXCEPT { return BOOST_ASIO_CONST_BUFFER(data, (N - 1) * sizeof(char)); } But this might cause trouble when using a const char array that is not null-terminated, since we then basically drop the last character. Would this be the best approach?

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[Spirit.Qi] failing to parse IP address octets
by Michael Powell 27 Nov '17

27 Nov '17

Hello, I've got the following parsers which are failing to find the correct attributes. I tried to parse in terms of uint_parser<uint8_t, 10, 1, 3>() at first, but this was not working properly. So I tried the following: _octet_rule = lexeme[ char_('0') | (char_('1') >> -(digit >> -digit)) | (char_('2') >> -((char_('0', '4') >> -(digit)) | (char_('5') >> -(char_('0', '5'))) | char_('6', '9') ) ) | (char_('3', '9') >> -digit) ]; Which is presently failing to find all three digits in the "20\d"-"24\d" use case. Octet itself parses correctly when I use this rule: _octet_rule >> !(char_); My octet test cases verify the entire range of 0-255 successfully, as well as the following invalid cases: VerifyOctet(-1, invalid_); VerifyOctet(1990, invalid_); VerifyOctet(2550, invalid_); VerifyOctet("255.", invalid_); VerifyOctet(256, invalid_); VerifyOctet(999, invalid_); VerifyOctet("abc", invalid_); VerifyOctet(123.456, invalid_); Converted to corresponding string, i.e. "1990" or "123.456". But when I combine that into the IP address rule, the test results occur: _octet_rule >> repeat(3)[char_('.') >> _octet_rule]; And the test results: CHECK_THAT( y, Equals(x) ) with expansion: "145.23.183.47" equals: "145.231.183.47" with message: Verifying address >>> 145.231.183.47 <<< FAILED: CHECK_THAT( y, Equals(x) ) with expansion: "189.21.29.11" equals: "189.211.29.11" with message: Verifying address >>> 189.211.29.11 <<< FAILED: CHECK_THAT( y, Equals(x) ) with expansion: "90.60.32.24" equals: "90.60.32.246" with message: Verifying address >>> 90.60.32.246 <<< FAILED: CHECK_THAT( y, Equals(x) ) with expansion: "22.59.144.140" equals: "223.59.144.140" with message: Verifying address >>> 223.59.144.140 <<< IP address test data is randomly generated, or combinatorially if I wanted to wait for all 4.3B or so test cases. However, I figure that as long as the Octet rule is working, it is reasonable to expect the Address rule may also work. Not sure why those last digits are being dropped, however. Or how the 1's can succeed where the 2's are failing. Any suggestions, Spirit folks? Thanks! Cheers, Michael Powell

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[serialization] property_tree::ptree bpta back-end, json, forward (upward) compatibility
by Sergey Spiridonov 27 Nov '17

27 Nov '17

Hi Current binary, text and xml archive back-ends allow to implement backward compatibility. This means that it is possible to read old serialization files with the new version of the serialization code, with the help of the version of the class which is stored in archive itself. Unfortunately forward compatibility is not possible to implement with the existing archive backends. Suppose we have class A with one field. struct A { template<class Archive> inline void serialize(Archive & ar, const unsigned int version ) { ar & BOOST_SERIALIZATION_NVP(field); } int field; }; Later we want to add a new field2. To be able to load the previously created file we need can use versioning. struct A { template<class Archive> inline void serialize(Archive & ar, const unsigned int version ) { ar & BOOST_SERIALIZATION_NVP(field); if(version > 0) { ar & BOOST_SERIALIZATION_NVP(field2); } } int field; int field2; }; BOOST_CLASS_VERSION(A, 1) But if we want the opposite, to load the old class from the file which was created from the new class (for example, if we use serialization to communicate between new and old version of application on the network), existing backends will fail. Why? The reason is that they expect certain field in certain order and do not allow unexpected unknown fields. Although with text and binary backend it is difficult to do, because field names are not stored, but xml backend has names for every field, so it can simply skip unknown fields. Unfortunately this is not implemented. I created [1] simple experimental archive which allows forward(upward) compatibility. It stores data in boost::property_tree::ptree (instead of std::stream), which, in turn, can be saved to json, if necessary. If the file which is loaded, has additional unknown fields (from future version), they will be ignored. [1] https://github.com/sena73/ptree_archive Intermediate storage of data in ptree has its advantages and disadvantages. Of course, this slows down things and requires more memory. On other hand, it allows to get upward compatibility automatically easily and even to process data before (or without) loading it into the target class. Also we get json and info storage for free. With little modification xml backend from property_tree can be used. Sure, it must be possible to create a version of boost::archive::xml which will be also capable to keep upward compatibility without necessity to load things into the property_tree first. Binary and text archives must be extended with field names to allow field skipping. -- Best regards, Sergey Spiridonov

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[release] Boost 1.66.0 Beta 1
by Daniel James 24 Nov '17

24 Nov '17

Boost release 1.66.0 beta 1 is now available at: <https://dl.bintray.com/boostorg/beta/1.66.0.beta.1/source/> The SHA256 checksums are as follows: e7b23e638e8c3a9da1512439385b04850829cea7bd56d8398677c096857d830b boost_1_66_0_b1.7z 5d0405eb73bd609ebcd54bbc96d4f1e2d97c51b96c4703706695ddd94f942d6b boost_1_66_0_b1.tar.bz2 f0f455e39bc47b2b670a17cb221687506e9a22dc478956d3d8aabb9cb835a7dc boost_1_66_0_b1.tar.gz 694c8b9e902b7981670bce166f675f3875c19326936db51aabd98d2ddfea9b45 boost_1_66_0_b1.zip For details of what's in the release, see <http://www.boost.org/users/history/version_1_66_0.html>. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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how to build boost binary libraries for GCC in windows 10
by Renfan Luo 23 Nov '17

23 Nov '17

Hi All As VS supports OpenMP2.0 only, I have to use GCC instead for my project with parallelisation in coding. I have downloaded Cygwin and installed the GCC 6.4.0 then updated it to the latest version 5.5.0 on my windows 10. All those binary libraries I built up in VS 2017, I guess, cannot be usable for GCC, so it may be necessary to rebuild them for boost 1.65.1 for GCC. Could you guys show me how to build them? Cheers Renfan

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