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[Range, Phoenix] What am I missing...
by Robert Jones 25 Apr '17

25 Apr '17

Hi Folks Can anyone explain the output of this program... #include <iostream> #include <boost/range/algorithm/copy.hpp> #include <boost/range/counting_range.hpp> #include <boost/range/adaptor/reversed.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/phoenix/bind/bind_function.hpp> #include <boost/phoenix/core/argument.hpp> int f( int i ) { return i * 2; } int main( ) { using boost::adaptors::reversed; using boost::adaptors::transformed; using boost::counting_range; using boost::copy; using boost::phoenix::arg_names::_1; copy( counting_range( 1, 5 ) | reversed | transformed( f ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; copy( counting_range( 1, 5 ) | reversed | transformed( bind( f, _1 ) ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; } Which is... 8 6 4 2 1768406272 1768406272 1768406272 1768406272 I'm using Gcc 4.6.2 & Boost 1.53 Thx All.

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[Serialization] issue with "Assertion `__null != bpos' failed"
by Francois Mauger 24 Apr '17

24 Apr '17

Hi Robert, all, In some of our libs, we use serialization through a base pointer: We have a base (abstract) class "a::base" which is available from a shared library "liba". We have created a new class "b::foo", inherited from "a::base", hosted in another shared lib "libb", "libb" being explicitly linked to "liba". In "libb", class "b::foo" is exported through : BOOST_CLASS_EXPORT_KEY2(b::foo,"b::foo") (in header foo.hpp) BOOST_CLASS_EXPORT_IMPLEMENT(b::foo) (in some libb's foo-serial.cpp source file) which I think is the right way to process to register a class in a compilation unit. In a test program, I (de)serialize 'b::foo' instances through a 'a::base' pointer. This mechanism has worked for years in all of our software chains. And today it works with our current production software system (ubuntu linux 16.04, g++ 5.4.0, GNU ld 2.26.1, Boost 1.60). However, we now face a runtime error on *some* of our boxes. The message is: <pre> ...test_app...: /path/to/boost/install/include/boost/archive/detail/oserializer.hpp:436: static void boost::archive::detail::save_pointer_type<Archive>::polymorphic::save(Archive&, T&) [ with T = a::base; Archive = boost::archive::xml_oarchive]: Assertion `__null != bpos' failed. Abort (core dumped) </pre> This error only occurs with XML or txt archives, but works like a charm with Christian's EOS portable binary ars. What is strange is that the code works on some of our systems but failed on other ones with the same compiler/linker/boost versions. The exception suggests some problem with class registration but I don't understand this (apparently) arbitrary behaviour. If any of you have a hint to help us to find the solution, it would be appreciated. thanks regards -- François

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really dumb question about quickbook
by Robert Ramey 21 Apr '17

21 Apr '17

I'm struggling with quickbook When I use the following [section:userapi User API] [include types/File.qbk] [include types/Hasher.qbk] [include types/Progress.qbk] [endsect] I don't the files included. But when I use [section:userapi User API] [include types/File.qbk] [include types/Hasher.qbk] [include types/Progress.qbk] [endsect] The other files ARE included. I've looked through the quickbook docs and for the life of me I can't find where the significance (if there is any) of spaces in the markup is explained. Could someone point me in the right direction? Robert Ramey

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[Boost-CRC] Warnings in crc_32_type
by tamas.ruszkai＠leica-geosystems.com 21 Apr '17

21 Apr '17

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[release] Boost 1.64.0
by Rene Rivera 20 Apr '17

20 Apr '17

Release 1.64.0 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This release contains one new library and numerous enhancements and bug fixes for existing libraries. For details, including download links, see < http://www.boost.org/users/history/version_1_64_0.html> You can also download directly from: < https://dl.bintray.com/boostorg/release/1.64.0/> To install this release on your system, see < http://www.boost.org/doc/libs/release/more/getting_started/index.html> Thanks to everyone who participated in this release. Thanks, -- The Boost Release Team Vladimir Prus, Rene Rivera, Marshall Clow, Eric Niebler, Daniel James, Beman Dawes

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[hana] create aribtrary tuples of integral_constants
by Steve Lorimer 19 Apr '17

19 Apr '17

Making use of Scott Schurr's str_const ( https://github.com/boostcon/cppnow_presentations_2012/blob/master/wed/schur…) I have a constexpr string. class StrConst { public: template<size_t N> constexpr StrConst(const char (&str)[N]) : str_(str) , len_(N - 1) { static_assert(N > 1, "not a string"); } constexpr operator const char*() const { return str_; } constexpr size_t size() const { return len_; } constexpr char operator[] (size_t i) const { return i < len_ ? str_[i] : throw std::out_of_range("invalid index"); } private: const char* const str_; const size_t len_; }; I have another constexpr function which returns the position of the first caret found in a string, starting from position n: constexpr int caretPos(const StrConst& str, size_t n = 0) { if (n == str.size()) return -1; if (str[n] == '^') return n; return caretPos(str, n+1); } I can use the results of caretPos to create a typedef for a std::tuple of std::integral_constants, where the size of the tuple is the number of carets found in the string, and each tuple element is an integral constant whose value is the position of the caret in the string. Here I manually construct this tuple: int main() { constexpr StrConst s("hello^world^"); constexpr int pos1 = caretPos(s); constexpr int pos2 = caretPos(s, pos1+1); using P1 = std::integral_constant<int, pos1>; using P2 = std::integral_constant<int, pos2>; using PosTuple = std::tuple<P1, P2>; static_assert(std::tuple_element_t<0, PosTuple>::value == 5, ""); static_assert(std::tuple_element_t<1, PosTuple>::value == 11, ""); } Question: I would now like to generalise this for any input string with any number of carets. template<size_t... Ns> using PosTuple = std::tuple<std::integral_constant<int, Ns>...>; How can I generate the sequence of Ns... required here using caretPos or some other means?

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[release] Boost 1.64.0 Release Candidate 1
by Rene Rivera 17 Apr '17

17 Apr '17

The release candidates for the 1.64.0 release are now available at: <https://dl.bintray.com/boostorg/beta/1.64.0.rc.1/> The SHA256 checksums are as follows: 49c6abfeb5b480f6a86119c0d57235966b4690ee6ff9e6401ee868244808d155 boost_1_64_0_rc1.7z 7bcc5caace97baa948931d712ea5f37038dbb1c5d89b43ad4def4ed7cb683332 boost_1_64_0_rc1.tar.bz2 0445c22a5ef3bd69f5dfb48354978421a85ab395254a26b1ffb0aa1bfd63a108 boost_1_64_0_rc1.tar.gz b99973c805f38b549dbeaf88701c0abeff8b0e8eaa4066df47cac10a32097523 boost_1_64_0_rc1.zip As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Boost Release Team -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- rrivera/acm.org (msn) - grafikrobot/aim,yahoo,skype,efnet,gmail

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Serialization support for colony container
by Brian Wood 17 Apr '17

17 Apr '17

Shalom It's looking like Matthew Bentley's colony container -- http://plflib.org -- is going to pass over Boost on it's way to the standard. I've added serialization support for this container to the C++ Middleware Writer and added some code that tests that support to my repo -- https://bitbucket.org/webenezer/onwards . I enjoyed Jon Kalb's CppChat show where he talked to Matthew about this container -- http://www.slashslash.info/cppchat/ https://www.youtube.com/watch?v=SFAJ238rBNw -- Brian Ebenezer Enterprises - In G-d we trust. http://webEbenezer.net

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[CallableTraits] Review results
by Louis Dionne 17 Apr '17

17 Apr '17

Dear Boost, I am pleased to announce that the CallableTraits library is CONDITIONALLY ACCEPTED into Boost. I counted the following formal reviews: - Bruno Dutra: Yes - Emil Dotchevski: Yes - John P. Fletcher: Yes - Klemens Morgenstern: Yes - Peter Dimov: Yes - Zach Laine: Yes The following people also participated to the review by providing informal feedback: - Edward Diener - Gavin Lambert - Niall Douglas - Paul Fultz II - Tim Song I also based my decision on previous experience I've had using the library, and some issues we faced in the Standard Committee where we could have used CallableTraits. I'd like to thank everyone who participated to the review for their feedback, and also Barrett Adair for his submission. The following lists the conditions for acceptance, and also summarizes the general feedback received during the review. GitHub issues are leveraged to make the tracking of these comments easier. Below, whenever I refer to #XYZ, the corresponding ticket can be found at https://github.com/badair/callable_traits/issues/XYZ To see all the issues that were discussed during the review, you can search for tickets labeled with `review` on GitHub (please allow some time for Barrett to update the new issues I just filed): https://github.com/badair/callable_traits/issues?page=1&q=+label%3Areview Conditions for acceptance ------------------------- The following are points that must be addressed for the library to be accepted. Once all of the associated GitHub issues are closed, I ask that the author post to this list with links to the closed issues. Unless major problems (having to do with the closed issues) are raised at that time, the library will be automatically accepted into Boost, no additional review required. - The library needs to clearly document the advantages of CallableTraits over FunctionTypes. Concrete examples must be given (at least one, preferably two). See #117. - The level of C++ conformance required for the whole library needs to be clearly stated in the documentation. Individual components should only document divergences from that base level of conformance. The current state of things is quite confusing for users. See #118. - The "algorithmic" parts of the library must be removed, since they are out of scope. This has already been partly done in issue #114, but the following algorithms must be discussed too (let's follow up in #114): + args_at + clear_args + pop_front_args + push_front_args + expand_args_right + expand_args_left - The lazy metafunctions and predicate traits should be SFINAE-friendly, just like the aliases are. I think this inconsistency is a big deal, enough to be a condition for acceptance. See #134. Summary of the feedback received -------------------------------- The following is a compilation of other points that were made during the review, but which are not requirements for acceptance. I trust, but do not require, that all of those points will be considered by the author: - There is a loss of information with the `args` metafunction. For example, `void(T)` and `void(T, ...)` both give the same result. See #132. - Consider adding a way of obtaining the parameter list of a function without the type of `*this`. See #133. - The documentation uses the terms of art "implementation defined" and "undefined behavior" incorrectly. See #103 and #131. - The non-reference documentation should present at least one real-world use case. See #116. - The library should handle top-level cv-qualifiers. See #106. - Consider supporting different calling conventions (e.g. `__cdecl`). See #102. - Consider adding a pre-C++17 implementation of `is_invocable` and friends. See #119. - The documentation should clearly state that the library can be used without the rest of Boost. See #99. - Consider combining `expand_args` and `args` into a single metafunction with a default "output" parameter of `std::tuple`. See #126. - Consider adding `make_fn` and `make_mem_fn` metafunctions to construct a signature from a return type and a tuple of the arguments. See #113. - Consider renaming some traits, like `is_reference_member`. See #108. - Reword some parts of the documentation that look odd due to the use of passive tense. See #105. - Consider adding a version of `apply_member_pointer` which carries cv-qualifiers. See #138. - Consider adding `remove_member_cv_ref` and `copy_member_cv_ref`. See #139. - Why does `qualified_parent_class_of` always returns a const& for PMDs? See #112. - Why does `qualified_parent_class_of` return a ref-qualified type even for unqualified PMFs? See #112. A few of my own comments: - Consider using alphabetical order in the table of contents of the reference. See #135. - Consider renaming `apply_member_pointer` to something like `make_member`. See #136. - Consider dropping the `parent_` in `parent_class_of`, or adding a note to justify the name. See #137. Again, thanks to everyone who participated in the review, and congratulations to Barrett for his work! Regards, Louis Dionne

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How to setup log directory in an directory that is not fixed?
by Bruce 17 Apr '17

17 Apr '17

Hi, I am using boost.Log. I config the log using a logconfig.ini file. Now the requirement changed, we need to put the log in an directory specific to a login account. The account may change so we have to first create the directory then set the log output file to this directory. I tried to first log the logconfig.ini and then set the logging::add_file_log(...), but the file path set in the .ini files created too. If I don't setup the FileName in the .ini file, it throws a exception. Is there anyway to set the path and the file name separately? Or change the file path after loading the .ini config file? Thanks

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