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[Boost.Range] An issue with the documentation of 'remove_erase_if' algorithm
by Adam Romanek 12 Feb '13

12 Feb '13

Hi, I think there's an issue with the documentation of 'remove_erase_if' algorithm from Boost.Range library. It says: "remove_erase_if removes the elements x that satisfy pred(x) from the container. This is in contrast to the erase algorithm which merely rearranges elements." I believe it's not in contrast to the "erase" algorithm but rather the "remove" algorithm. WBR, Adam Romanek

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Future of Boost Windows Installers
by Dave Abrahams 11 Feb '13

11 Feb '13

Hi, As many of you already know, I'm going to work at Apple in late February, and BoostPro is closing its doors. For many years, the Boost Getting Started Guide has suggested that Windows users pop over to BoostPro's website and use the latest installer to get Windows binaries. We'd like to donate to the community the technology used to build those installers. If anyone would like to pick up the job of creating them, we'd be happy to offer guidance. Right now I'm on a plane where an uplink to GitHub is creeping along at 4KB/s, so I've been pushing the stuff up in bits and pieces and the latest stuff isn't up there, but it's going to http://github.com/boostpro/installer and will be complete within 24 hours. Whatever happens with this installer code, someone is going to need to update the Getting Started Guide, either to point at the installer's new home, or to remove references to it. -- Dave Abrahams BoostPro Computing Software Development Training http://www.boostpro.com Clang/LLVM/EDG Compilers C++ Boost

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Release branch now open for merging
by Marshall Clow 11 Feb '13

11 Feb '13

The release branch (https://svn.boost.org/svn/boost/branches/release) is open for merging all stable changes from trunk, including bug fixes and major upgrades to existing libraries. Breaking changes should be coordinated via the mailing list with the developers of the other libraries affected. New libraries may be added, but require permission of a release manager. In other words, merging *does not* require permission from a release manager, except for new libraries. Boost Calendar with the release schedule: http://www.boost.org/development/index.html Release schedule explanation: http://svn.boost.org/trac/boost/wiki/ReleaseSchedule Release practices for developers: http://svn.boost.org/trac/boost/wiki/ImprovingPractices -- The Release Managers, Beman Dawes Daniel James Eric Niebler Marshall Clow Rene Rivera Vladimir Prus

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[iostreams] mapped_file_source fails for zero sized file
by Michael Marcin 11 Feb '13

11 Feb '13

While testing out iostreams memory mapped file source I ran into an issue where it throws when opening a zero sized file (testing on windows 7 vc11 x64). for example something like: namespace io = boost::iostreams; namespace fs = boost::filesystem; fs::path path("C:\\boost\\boost_1_53_0\\libs\\context\\src\\dummy.cpp"); io::stream<io::mapped_file_source> file( path ); Will throw: failed create mapping: The volume for a file has been externally altered so that the opened file is no longer valid. From: http://tinyurl.com/cx2b9ru "When you do not want the size of the file to change (for example, when mapping read-only files), call CreateFileMapping and specify zero for both dwMaximumSizeHigh and dwMaximumSizeLow. Doing this creates a file mapping object that is exactly the same size as the file. Otherwise, you must calculate or estimate the size of the finished file because file mapping objects are static in size; once created, their size cannot be increased or decreased. An attempt to map a file with a length of zero in this manner fails with an error code of ERROR_FILE_INVALID. Programs should test for files with a length of zero and reject such files." I don't see anything in the docs that would lead me to believe this should throw. Rather I would expect: std::istream_iterator<char>(file) == std::istream_iterator<char>()

1 0

Picking overload with the most specific concept
by Louis Dionne 11 Feb '13

11 Feb '13

Hi, I was playing around today and I achieved to do something I find quite cool. I would like to know whether the technique/general principle is of any interest. Basically, it allows to overload functions based on the modeling of a concept by a type without having to write complicated enable_ifs. It does come with some problems and it is not very general for the moment, but it's a first shot. Here we go: #include <duck.hpp> // the library where I implemented that #include <forward_list> #include <utility> #include <vector> // Generates some boilerplate required to enable concept overloading for // a function named `my_distance`. Ignore this for now. DUCK_ENABLE_CONCEPT_OVERLOADING( my_distance, my_distance(std::declval<Iterator>(), std::declval<Iterator>(), State()), typename Iterator ) struct random_access_version_picked { }; struct forward_version_picked { }; // The State template parameter will be used to carry information during // the resolution. tag::my_distance was defined by the above macro. template <typename Iterator, typename State = tag::my_distance> // This can be seen like an enable_if with some more functionality. typename duck::requires< // This overload is picked iff Iterator models RandomAccessIterator // and no other overload for a more specific concept exist. // Concepts are MPL metafunction classes, so there's no magic here. duck::model_of<duck::RandomAccessIterator, Iterator> // Could add more duck::model_of clauses here , duck::overload_resolution_state<State> // required for the mechanics , duck::template_parameters<Iterator> // ditto , random_access_version_picked>::type // return type my_distance(Iterator, Iterator, State = State()) { return random_access_version_picked(); } // Same thing for the ForwardIterator implementation. template <typename Iterator, typename State = tag::my_distance> typename duck::requires< duck::model_of<duck::ForwardIterator, Iterator> , duck::overload_resolution_state<State> , duck::template_parameters<Iterator> , forward_version_picked>::type my_distance(Iterator, Iterator, State = State()) { return forward_version_picked(); } int main() { std::forward_list<int> list; std::vector<int> vec; forward_version_picked forward = my_distance(begin(list), end(list)); random_access_version_picked random = my_distance(begin(vec),end(vec)); } This example works with Clang 3.3 and GCC 4.8. For those interested in seeing more, the full library is available at: http://github.com/ldionne/duck Look for the `next` branch. The file involved with the above mechanics is include/duck/requires.hpp. Also see the test in test/requires.cpp. Regards, Louis Dionne

1 0

[Git] Status update
by Dave Abrahams 10 Feb '13

10 Feb '13

Please see https://github.com/ryppl/boost-svn2git/wiki if you're interested in the status of modularized history conversion. -- Dave Abrahams

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[smart_ptr] !defined(BOOST_NO_CXX11_SMART_PTR) does not imply !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
by Michel Morin 10 Feb '13

10 Feb '13

`!defined(BOOST_NO_CXX11_SMART_PTR)` does not necessarily mean that the compiler support of rvalue references is available. For example, when I use shared_ptr (on trunk) with clang + libc++ in a C++03 mode, I get warnings something like boost/smart_ptr/shared_ptr.hpp:556:51: warning: rvalue references are a C++11 extension [-Wc++11-extensions] shared_ptr & operator=( std::unique_ptr<Y, D> && r ) Regards, Michel

3 4

[preprocessor] enabling variadics support
by Gennadiy Rozental 09 Feb '13

09 Feb '13

Hi, It appears PP variadics support is disabled on wide range of compilers where it is in fact working (at least It seems to be). This includes Clang and PGI. Can we enable it now? Gennadiy

3 2

[variant] Please vote for behavior (Was: Basic rvalue and C++11 features seupport)
by Antony Polukhin 08 Feb '13

08 Feb '13

Current implementation of recursive_wrapper move constructor is not optimal: recursive_wrapper<T>::recursive_wrapper(recursive_wrapper&& operand) : p_(new T(std::move(operand.get()) )) { } During descussion were made following proposals: I: Leave it as is - bad performance - can not provide noexcept guarantee II: Set operand.p_ to NULL, add BOOST_ASSERT in get operations + good performance + provides noexcept guarantee for move constructor + optimization will be used even if varinat has no type with trivial default constructor + easy to implement - triggers an assert when user tries to reuse moved object - adds an empty state to the recursive_wrapper III: Make recursive_wrapper and variant cooperate, enable move for varinat in the presence of recursive_wrappers only when there is at least one type that is nothrow-default-constructible, regardless of whether it's current. It is easyer to understand by example: typedef variant<int, recursive_wrapper<foo>> V; V v1( std::move(v2) ); This move-constructs v1 from v2 and leaves int() into v2. + good performance + provides noexcept guarantee for rcursive_wrapper + does not adds an empty state - optimization won't trigger if varinat has no type with trivial default constructor - hard to implement - user may be obscured by the fact, that v2 from the example now contains int IV: After move away, delay construction of type held by recursive_wrapper till it will be be required. +/- good performance? but more checks + provides noexcept guarantee for rcursive_wrapper + does not adds an explicit empty state + optimization will be used even if varinat has no type with trivial default constructor +/- not hard to implement --- additional requirement for type T of recursive_wrapper: it must be default constructible - less obvious behavior for user (for example get() function would construct values, allocate memory and can possibly throw) Please, vote for solution or propose a better one. P.S.: As I know Joel de Guzman votes for solution II (and totally agains solution I, because it is too slow). I wanted to leave as is (solution I) or use solution IV, but Joel talked me to solution II. P.P.S.: More info can be obtained from ticket #7718 https://svn.boost.org/trac/boost/ticket/7718 and previous series of letters. -- Best regards, Antony Polukhin

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[asio] socks and http connect proxy support
by ecyrbe 08 Feb '13

08 Feb '13

Hi, I made a boost asio client stream to handle tcp proxy support (both socks v4/v5 and http connect). I think boost asio lack this type of support, so i'm asking if there is any interest to integrate such a feature in boost.Asio? I'm mainly asking this question to boost.Asio maintainers. if you want i can come with a patch for a proxyfied_stream<Stream> template class. Regards, ecyrbe.

1 0

[Git] Tracking conversion milestones and issues
by Beman Dawes 08 Feb '13

08 Feb '13

To track the Git and modular Boost conversion milestones and issues, see github.com/ryppl/boost-svn2git/issues/milestones github.com/ryppl/boost-svn2git/issues --Beman

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[log] v2 Initialisation, default sink behaviour and filtering documentation
by Mats Taraldsvik 08 Feb '13

08 Feb '13

Hi, I'm in the process of adopting a logging library, so the timing of the Boost.Log v2 "status report" - for me - could not have been better. :) This library is awesome, thank you for making it! -- I am in the process of moving beyond the default sink now, and had some issues. I tried to add the sinks after my logger object had been default initialized, and this caused some problems (partial streams/corruption, mostly). Currently I'm calling core->remove_all_sinks() to remove the default sink. Are there any "best practices" here? Perhaps it would be a good idea to add these "requirements" to the documentation, if they are not there already and I missed them? :) -- I also noticed that the severity filter examples are : logging::core::get()->set_filter ( logging::trivial::severity >= logging::trivial::info ); >From "Setting up sinks", and sink->set_filter(expr::attr< int >("Severity") >= 2); (i.e. comparing the Severity with an int) when moving to the more advanced section in "Sink frontends". Could you adjust one of the examples in "Sink frontends" to use the severity_level type (that the documentation introduces in the tutorial "Adding more information to log: Attributes") directly? For example: sink->set_filter(expr::attr< severity_level >("Severity") >= warning); Or explaining this in "Log record formatting". I had trouble understanding this at first, but I might be the only one :). Thought I'd mention it anyway. -- Regards, Mats Taraldsvik Norkart AS norkart.no

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[bind] Request: use result_of instead of result_type for functors
by Jason 07 Feb '13

07 Feb '13

One of the drawbacks of using functors with Boost.Bind is that the result type of the functor must be specified either as a typedef inside the functor's definition or as a template argument when building the binding. As the documentation states it: "In the general case, the return type of the generated function object's operator() has to be specified explicitly (without a typeof operator the return type cannot be inferred)" It seems that result_of() would be a good implementation of the "typeof" operator referenced in the above, instead of relying upon a single result_type typedef inside the functor struct/class. This would allow the use of functors whose result type depends upon the arguments passed to the functor. It looks like there was a proof-of-concept patch submitted for this a couple years ago: https://svn.boost.org/trac/boost/ticket/4542 It doesn't appear to have received any attention, however. Is this something that might happen? -- View this message in context: http://boost.2283326.n4.nabble.com/bind-Request-use-result-of-instead-of-re… Sent from the Boost - Dev mailing list archive at Nabble.com.

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[log] missing file in trunk?
by Michael Caisse 07 Feb '13

07 Feb '13

boost/log/filters.hpp seems to be missing from https://boost-log.svn.sourceforge.net/svnroot/boost-log/trunk/boost-log revision 827. Ideas? michael -- Michael Caisse ciere consulting ciere.com

2 3

[bbv2] pdf doc missing?
by Michael Marcin 07 Feb '13

07 Feb '13

http://www.boost.org/doc/libs/1_53_0/tools/build/v2/index.html links to http://www.boost.org/doc/libs/1_53_0/tools/build/v2/doc/userman.pdf Which appears to be broken 404 Not Found File "/home/grafik/www.boost.org/archives/live/boost_1_53_0/tools/build/v2/doc/userman.pdf" not found. In fact the last working one seems to be http://www.boost.org/doc/libs/1_37_0/tools/build/v2/doc/userman.pdf

1 0

[Function] : Memory allocation upon bind()
by Harry van Haaren 06 Feb '13

06 Feb '13

Hi All, Summary: Boost::bind() allocates memory on the heap. In my situaion it is necessary to use manual memory pool instead of heap allocation, to conform with real-time timing requirements. (no malloc() calls allowed in real-time code) A solution might be writing a custom allocator for the boost::bind()'s data, and use a pre-allocated memory pool with the "placement" new( void* ) to write directly into it. I've found that there was a discussion on std::allocator support for std::bind and std::function here: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2308.html I'm not very familiar with the internals of bind() and Function in general, hence advice is appreciated. What is the status of boost::bind() and custom allocators? Is there a chance this could work? Am I missing some "easy" workaround or solution? Thanks for reading, -Harry

2 2

[log][phoenix] Bound arguments not protoified?
by Andrey Semashev 06 Feb '13

06 Feb '13

Hi, I have a problem with Boost.Phoenix v3 bind implementation when used with attribute keywords from Boost.Log. For some reason phoenix::bind does not apply proto::detail::protoify to the bound arguments which breaks compilation of some formatting expressions in Boost.Log. Here's an example: namespace logging = boost::log; namespace expr = boost::log::expressions; namespace phoenix = boost::phoenix; // Custom severity level formatting function std::string severity_level_as_urgency( logging::value_ref< logging::trivial::severity_level, logging::trivial::tag::severity > const& level); // The function initializes the logging library void init_logging() { // ... sink->set_formatter ( expr::stream << phoenix::bind(&severity_level_as_urgency, logging::trivial::severity) ); } The intended behavior of this code is to invoke severity_level_as_urgency function with severity level value extracted from a log record and put the result of this function into a stream, thus forming a formatted representation of the record. trivial::severity is a keyword of type expr::attribute_keyword< ... >. Keywords themselves should never actually be embedded into phoenix expressions, instead I have attribute_actor that implements all the necessary work to extract attribute values. I have specialized proto::detail::protoify template for attribute_keyword (including references and reference_wrappers thereof) so that it is automatically converted to attribute_actor whenever it participates in expressions. But it doesn't work with the above code, Boost.Phoenix embeds attribute_keyword as is into the expression. This results in the error I posted in the end of the post. I realize that proto::detail::protoify is not for public use and may not be intended for my use case but I did not find any other way to implement what I described. Anyway, I think bind should treat bound arguments as child subexpressions and protoify them. Is that right? In case if you want to see the complete code of the example and/or Boost.Log, you can check it out from SVN: svn co https://boost-log.svn.sourceforge.net/svnroot/boost- log/branches/bleeding-edge boost-log The example resides in libs/log/example/doc/extension_app_launcher.cpp. I have modified it to call or_none() on trivial::severity so that the example compiles; in order to reproduce the problem you have to remove this call (it sould be performed by my protoify specialization instead). Compilation error: In file included from ./boost/phoenix/core/preprocessed/expression.hpp:12:0, from ./boost/phoenix/core/expression.hpp:21, from ./boost/phoenix/core/argument.hpp:14, from ./boost/phoenix/core.hpp:17, from ./boost/phoenix/phoenix.hpp:11, from ./boost/phoenix.hpp:11, from libs/log/example/doc/extension_app_launcher.cpp:13: ./boost/phoenix/core/preprocessed/expression_10.hpp: In instantiation of ‘static boost::phoenix::expr_ext<Actor, Tag, A0, A1>::type boost::phoenix::expr_ext<Actor, Tag, A0, A1>::make(typename boost::call_traits<A0>::param_type, typename boost::call_traits<A1>::param_type) [with Actor = boost::phoenix::actor; Tag = boost::phoenix::detail::tag::function_eval; A0 = boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)>; A1 = boost::log::v2s_mt_posix::expressions::attribute_keyword<boost::log::v2s_mt_posix::trivial::tag::severity>; boost::phoenix::expr_ext<Actor, Tag, A0, A1>::type = boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list2<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)> >, 0l>, boost::log::v2s_mt_posix::expressions::attribute_actor<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::fallback_to_none, boost::log::v2s_mt_posix::trivial::tag::severity, boost::phoenix::actor> >, 2l> >; typename boost::call_traits<A0>::param_type = const boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)>&; typename boost::call_traits<A1>::param_type = const boost::log::v2s_mt_posix::expressions::attribute_keyword<boost::log::v2s_mt_posix::trivial::tag::severity>&]’: ./boost/phoenix/bind/bind_function.hpp:45:83: required from ‘const typename boost::phoenix::detail::expression::function_eval<boost::phoenix::detail::function_ptr<1, RT, RT (*)(T0)>, A0>::type boost::phoenix::bind(RT (*)(T0), const A0&) [with RT = std::basic_string<char>; T0 = const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&; A0 = boost::log::v2s_mt_posix::expressions::attribute_keyword<boost::log::v2s_mt_posix::trivial::tag::severity>; typename boost::phoenix::detail::expression::function_eval<boost::phoenix::detail::function_ptr<1, RT, RT (*)(T0)>, A0>::type = boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list2<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)> >, 0l>, boost::log::v2s_mt_posix::expressions::attribute_actor<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::fallback_to_none, boost::log::v2s_mt_posix::trivial::tag::severity, boost::phoenix::actor> >, 2l> >]’ libs/log/example/doc/extension_app_launcher.cpp:92:91: required from here ./boost/phoenix/core/preprocessed/expression_10.hpp:98:17: warning: missing braces around initializer for ‘boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list2<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)> >, 0l>, boost::log::v2s_mt_posix::expressions::attribute_actor<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::fallback_to_none, boost::log::v2s_mt_posix::trivial::tag::severity, boost::phoenix::actor> >, 2l> >::expr_type {aka boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list2<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)> >, 0l>, boost::log::v2s_mt_posix::expressions::attribute_actor<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::fallback_to_none, boost::log::v2s_mt_posix::trivial::tag::severity, boost::phoenix::actor> >, 2l>}’ [-Wmissing-braces] ./boost/phoenix/core/preprocessed/expression_10.hpp:98:17: warning: missing braces around initializer for ‘boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list2<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)> >, 0l>, boost::log::v2s_mt_posix::expressions::attribute_actor<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::fallback_to_none, boost::log::v2s_mt_posix::trivial::tag::severity, boost::phoenix::actor> >, 2l>::proto_child0 {aka boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)> >, 0l>}’ [-Wmissing- braces] ./boost/phoenix/core/preprocessed/expression_10.hpp:98:17: error: could not convert ‘boost::proto::make_expr<boost::phoenix::detail::tag::function_eval, boost::proto::domainns_::basic_default_domain, boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)>, boost::log::v2s_mt_posix::expressions::attribute_keyword<boost::log::v2s_mt_posix::trivial::tag::severity> >((* & a0), (* & a1))’ from ‘const type {aka const boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list2<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)> >, 0l>, boost::log::v2s_mt_posix::expressions::attribute_keyword<boost::log::v2s_mt_posix::trivial::tag::severity> >, 2l>}’ to ‘boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)> >, 0l>::proto_child0 {aka boost::phoenix::detail::function_ptr<1, std::basic_string<char>, std::basic_string<char> (*)(const boost::log::v2s_mt_posix::value_ref<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::trivial::tag::severity>&)>}’ ./boost/phoenix/core/preprocessed/expression_10.hpp:98:17: error: no matching function for call to ‘boost::log::v2s_mt_posix::expressions::attribute_actor<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::fallback_to_none, boost::log::v2s_mt_posix::trivial::tag::severity, boost::phoenix::actor>::attribute_actor(<brace-enclosed initializer list>)’ ./boost/phoenix/core/preprocessed/expression_10.hpp:98:17: note: candidates are: In file included from ./boost/log/expressions.hpp:20:0, from libs/log/example/doc/extension_app_launcher.cpp:16: ./boost/log/expressions/attr.hpp:174:14: note: boost::log::v2s_mt_posix::expressions::attribute_actor<T, FallbackPolicyT, TagT, ActorT>::attribute_actor(const base_type&) [with T = boost::log::v2s_mt_posix::trivial::severity_level; FallbackPolicyT = boost::log::v2s_mt_posix::fallback_to_none; TagT = boost::log::v2s_mt_posix::trivial::tag::severity; ActorT = boost::phoenix::actor; boost::log::v2s_mt_posix::expressions::attribute_actor<T, FallbackPolicyT, TagT, ActorT>::base_type = boost::phoenix::actor<boost::log::v2s_mt_posix::expressions::attribute_terminal<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::fallback_to_none, boost::log::v2s_mt_posix::trivial::tag::severity> >] ./boost/log/expressions/attr.hpp:174:14: note: candidate expects 1 argument, 0 provided ./boost/log/expressions/attr.hpp:156:7: note: boost::log::v2s_mt_posix::expressions::attribute_actor<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::fallback_to_none, boost::log::v2s_mt_posix::trivial::tag::severity, boost::phoenix::actor>::attribute_actor(const boost::log::v2s_mt_posix::expressions::attribute_actor<boost::log::v2s_mt_posix::trivial::severity_level, boost::log::v2s_mt_posix::fallback_to_none, boost::log::v2s_mt_posix::trivial::tag::severity, boost::phoenix::actor>&) ./boost/log/expressions/attr.hpp:156:7: note: candidate expects 1 argument, 0 provided

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-commits list broken?
by Marshall Clow 06 Feb '13

06 Feb '13

I just noticed that I haven't received any mail from boost-commits since 1/29. The archives on the web site stop at 1/14. Any ideas for giving the server a thwack? -- Marshall Marshall Clow Idio Software <mailto:mclow.lists@gmail.com> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait). -- Yu Suzuki

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[range] missing includes in any_range.hpp
by svarneticist 05 Feb '13

05 Feb '13

Hello, I get errors when I try to use boost/range/any_range.hpp It appears that boost/range/detail/any_iterator.hpp needs #include <boost/utility/enable_if.hpp> and boost/range/detail/any_iterator_wrapper.hpp needs #include <boost/range/concepts.hpp> Thank you -- View this message in context: http://boost.2283326.n4.nabble.com/range-missing-includes-in-any-range-hpp-… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Re: [boost] Is there any interest in static constructors?
by Alexander Stoyan 05 Feb '13

05 Feb '13

Okay, I believe I need to provide a really good example that can show the need of static construction with no preliminary calls to initialization functions. The example if part of my work project: - I have two layers: presentation and model. - Each layer work in its own thread because presentation must remain responsive whatever happens in model. - Model itself is an abstract layer, the actual logic implementation is implemented in specific agents, so the model is not aware of the agents. - Agents are asynchronous tasks. - I have DatabaseFacade utility class, internal data of which require some preliminary initialization, like setting initial values, creating locks, filling hash maps, but not actual connection because it's a proxy to real database object. - All agents use the DatabaseFacade asynchronously. These are the possible scenarios of initialization of DatabaseFacade internal data: 1. Make a call to DatabaseFacade::initialize() from main (or other wiring code), thus making main aware about DatabaseFacade, i.e. introduce an unnecessary dependency. 2. Call DatabaseFacade::initialize() from model construction, again introducing an unnecessary dependency, because the abstract model doesn't care about some specific needs of some agents. 3. Call DatabaseFacade::initialize() during specific agent construction. But another agent can be inside a call to DatabaseFacade::initialize(). So, I'd need to wrap it in critical section. But the critical section itself has to be initialized before agents start. Should I introduce dependency on this specific critical section to the abstract model? Nop. Should I wrap DatabaseFacade::initialize() inside in a static critical section thus making assumptions about clients of the function? Nop again. And by introducing public method DatabaseFacade::initialize() I will open a possibility for double initialization. Of course I can insert checks, but the checks can reveal problems at run-time only. So it's more correct to allow a class to initialize its internal data itself on its own discretion, thus writing robust API that cannot be misused: "Anything that can go wrong will go wrong" - Murphy's Law ;) Thank you. ______________________________ With best regards, Alexander Stoyan

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Re: [boost] Is there any interest in static constructors?
by Alexander Stoyan 05 Feb '13

05 Feb '13

Hello everybody, Sorry for late response. To Mateusz. Thank you for a good point, I have updated my initial blogpost with with clear statement of the goal. And I also corrected naming and put some extra comments. To Mathias. >> What's the functional difference between putting it as a type list and >> putting it as code? Not sure that I understood your question correctly, but if you meant differences between dependencies in the static_dependencies list and dependencies caused by calling initialization from main, then the difference is clear: if we put dependencies B and C to static_dependencies list when declaring class A, then only class A declaration becomes dependent on B and C. But if we require a call to A::initialize, B::initialize and C::initialize from main, then main becomes dependent on A, B and C. This way your startup code will be dependent on everything like that, that's not right. >> If you want it to be initialized before main, then use global variables or static members. Ok, try to answer your question yourself: struct A { static A& instance() { ... } } struct B { static A& instance() { ... } } struct C { static A& instance() { ... } } ... static A& forceAConstr = A::instance(); static B& forceBConstr = A::instance(); static C& forceCConstr = A::instance(); ... int main() { ... } Can you guarantee the order of construction for A, B and C in this case when standard explicitly states that the order of initialization is not determined? >> But then you have to make sure no threads exist prior to entering main. >> Unlike for static variables in functions, global constructors are not thread-safe. Starting threads before main execution is a bad idea itself, so don't do it. >> I have no idea what you're talking about. The compiler cannot remove >> things if it changes observable behaviour, outside of a few situations >> where copy constructors can be elided. In my code you can find a declaration and initialization of bool static_constructible<T, Dependencies>::constructed. So, if this variable is not referenced in the code it never get initialized. At least this is how VS11 compiler works. So in order to refer this variable all data access functions have to make a call to static_constructible<T, Dependencies>::ensure_static_constructed. This way if you call a data access function from main, which calls ensure_static_constructed, then static_constructible::constructed becomes referenced! >> There is an "isinside" boolean. That's only made for cases if a derived class from singleton does not provide his own static constructor. If you remove B::static_construct() the code will work fine anyway. >> A given order can still be forced. Unless it's through compile configuration, provide an example please. Otherwise, having long lists of initialization orders for all supported compilers is error prone. The code itself has to describe itself as much as possible. I appreciate your attention. Thank you. ______________________________ With best regards, Alexander Stoyan

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[gil] compiler error with clang in c++11 mode
by Christian Henning 05 Feb '13

05 Feb '13

Hi there, Can someone shed some light on the following compiler errors: c:\boost\boost\gil/channel_algorithm.hpp:54:85: error: non-type template argument evaluates to -1, which cannot be narrowed to type 'unsigned long long' [-Wc++11-narrowing] struct unsigned_integral_max_value : public mpl::integral_c<UnsignedIntegralChannel,-1> {}; ^ c:\boost\boost\gil/channel_algorithm.hpp:204:19: note: in instantiation of template class 'boost::gil::detail::unsigned_integral_max_value<unsigned long long>' requested here if (src > unsigned_integral_max_value<uintmax_t>::value - div2) I only get those in c++11 mode. The code to trigger them is: #include <boost\gil\gil_all.hpp> int main() { return 0; } I'm using clang 3.2 on Windows with CodeBlocks. Thanks, Christian

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[type_traits] Request: is_iterable
by Nevin Liber 05 Feb '13

05 Feb '13

I'd like to make a request for an is_iterable<T> type trait, which detects if a type can be used in C++11 range-based for. I have a prototype which currently meets my needs (I can make it available; it detects if both std::begin(c) and std::end(c) can be called), but I'm wondering: a) What should the name be? (I'm not married to is_iterable) b) Should there be a second template parameter indicating the type returned by derefencing the iterator, defaulting to don't care. c) What should the C++03 behavior be? d) Is there someone with more expertise than I willing to implement a robust version of it? Does this sound like a good idea? -- Nevin ":-)" Liber <mailto:nevin@eviloverlord.com> (847) 691-1404

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Boost 1.53.0 released!
by Marshall Clow 04 Feb '13

04 Feb '13

Release 1.53.0 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 five new libraries and numerous enhancements and bug fixes for existing libraries. New Libraries: * Atomic: C++11-style atomic<>, from Helge Bahmann, maintained by Tim Blechmann. * Coroutine: Coroutine library, from Oliver Kowalke. * Lockfree: Lockfree data structures, from Tim Blechmann. * Multiprecision: Extended precision arithmetic types for floating point, integer and rational arithmetic from John Maddock and Christopher Kormanyos. * Odeint: Solving ordinary differential equations, from Karsten Ahnert and Mario Mulansky. For details, including download links, see http://www.boost.org/users/news/version_1.53.0 You can also download directly from SourceForge: http://sourceforge.net/projects/boost/files/boost/1.53.0/ To install this release on your system, see http://www.boost.org/doc/libs/release/more/getting_started/index.html Thanks, --The Boost release team Beman Dawes Daniel James Eric Niebler Marshall Clow Rene Rivera Vladimir Prus

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[1.53] Too late for doc fixes?
by John Maddock 04 Feb '13

04 Feb '13

Am I correct in assuming that it's too late to fix typos in docs: https://svn.boost.org/trac/boost/ticket/7958 ? Thanks, John.

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