May 2010 - Boost - lists.preview.boost.org

Re: [boost] Namespace for a Boost Hashing Library
by Anders Dalvander 10 May '10

10 May '10

Scott McMurray wrote: > Some possibilities: > > - boost::hashes > - boost::hash_algo or boost::hash_algorithms > - boost::hashing or boost::hashing_algorithms > - boost::digests or boost::message_digest > - boost::fingerprint (or boost::dactylogram) > > Which one(s) do you prefer or dislike? > > Thanks, > ~ Scott McMurray > My votes goes to, in order: 1. boost::hash_algo 2. boost::crypto_hash 3. boost::hashes 4. boost::c11c_hash (not an actual proposal) Regards, Anders Dalvander

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[website] favicon path was incorrect
by Jeremiah Willcock 10 May '10

10 May '10

Look at https://svn.boost.org/favicon.ico or the file I attached; /htdocs/site/favicon.ico is still the old, larger icon. -- Jeremiah Willcock

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New list moderators needed!
by Beman Dawes 10 May '10

10 May '10

It is high time we added additional mailing list moderators. The current moderators have been in place for years, but in the meantime their day job responsibilities have changed, or other distractions are preventing them from giving list moderation the attention it deserves. While the current moderators will make the final decision, it would be helpful to hear nominations from the list for several new moderators. Who are some regular posters with the "right stuff" to keep the list civil, productive, and interesting? Actually moderating postings doesn't take a lot of time, since only postings from new posters need manual moderation. But we need moderators who read all or most postings, and step in when guidelines aren't being observed. --Beman

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[cstdint] Why no cstdint.hpp merge from trunk for 1.43.0?
by Number Cruncher 10 May '10

10 May '10

I've just been looking at the latest 1.43 and noticed the same issue with the redefinition of INT*_C macros as 1.42, yet the fix was committed to the trunk 3 months ago: https://svn.boost.org/trac/boost/changeset/59430/trunk/boost/cstdint.hpp Any ideas why this didn't make the 1.43 release? Thanks, Simon

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[asio] boost include problem
by Elimentz 10 May '10

10 May '10

Hey I'm trying to use a Boost asio Basic_serial_port in my project, so I include the file asio.hpp like this: #include <boost/asio.hpp> This file contains a lot of other includes, but it seems it is impossible for my project to include these, not a single one... how can I fix this? I mean, this should work, right? these files were written by the developers themselves!! -- View this message in context: http://old.nabble.com/-asio--boost-include-problem-tp28502931p28502931.html Sent from the Boost - Dev mailing list archive at Nabble.com.

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[thread] thread_specific_ptr and static initialization order
by Tanguy Fautré 09 May '10

09 May '10

Hi, After upgrading from 1.42 to 1.43 (using VC10 x64), I encounter an access violation related to thread_specific_ptr. The program used to run fine with previous version of Boost on several platforms (Win x32, Win x64 and Linux x64). I've managed to create a small program that reproduces the problem. It seems to be a static initialization order related problem. If the TSS is initialized by a static object, the program fails (nullptr exception). However, if the static object is commented out, and the TSS is solely initialized in the main, the program runs fine. Is thread_specific_ptr supposed to work even when initialized by another static object? Or does it require to be initialized only after entering main? Regards, Tanguy #include <boost/thread/thread.hpp> #include <boost/thread/tss.hpp> #include <iostream> #include <stdexcept> namespace { boost::thread_specific_ptr<int> tss; void verifyTss() { if (tss.get() == nullptr) throw std::runtime_error("verifyTss failed (nullptr)"); } class InitTss { public: InitTss() { tss.reset(new int); } }; InitTss init_tss; } int main(int argc, char argv[]) { try { tss.reset(new int); verifyTss(); boost::thread thread([] () { tss.reset(new int); }); thread.join(); verifyTss(); } catch (const std::exception & error) { std::cerr << "ERROR: " << error.what() << std::endl; } }

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Is release branch open for merges?
by Andrey Semashev 09 May '10

09 May '10

Now that 1.43 is released, is the release branch open for merges?

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[lambda][cast] 1.42 and 1.43 boost/lambda/cast.hpp requires #include before it - bug?
by Krzysztof Czainski 09 May '10

09 May '10

I have noticed, that with includes in this order: #include <boost/lambda/cast.hpp> #include <boost/lambda/lambda.hpp> later using ll_static_cast fails to compile with first message (gcc-4.3): /usr/include/boost/lambda/casts.hpp:93: error: ‘return_type_N’ is not a template However, including lambda.hpp before cast.hpp fixes the error. I have tested this with boost 1.42.0 and 1.43.0. Regards Krzysztof Czainski

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Like boost::enable_if, but takes a "priority number" and changes overload resolution order
by Dennis Ferron 09 May '10

09 May '10

>From the Boost documentation: "The enable_if family of templates is a set of tools to allow a function template or a class template specialization to include or exclude itself from a set of matching functions or specializations based on properties of its template arguments." Sometimes instead of completely excluding a function from overload resolution, I only really want to "tweak" C++'s overload resolution order, or disambiguate an edge case. Instead of relying on C++'s overload priorities, sometimes I'd like to explicitly set the overload priority, like this: template <typename T> void func(boost::overload_priority<1> dummy, ArgType1 arg) {} template <typename T> void func(boost::overload_priority<2> dummy, ArgType2 arg) {} template <typename T> void func(boost::overload_priority<3> dummy, ArgType3 arg) {} Whereas enable_if causes a "hard" error to trigger SFINAE and take a function out of consideration, overload_priority would have some sort of "soft" effect that "tricks" the C++ compiler into thinking it is a less specific match than it is, moving it down in the order of which gets chosen, without actually invalidating it. It isn't obvious that this is even possible, but then, I would never have believed "enable_if" was possible before I heard of it. Whereas enable_if works by wrapping the return type of the function, I believe this would have to wrap a function argument to work. What I have in mind is that the overload_priority class would look like this: template <int N> class overload_priority { public: overload_priority(int x) { ... } }; You would call the overloaded function like this: func(0, the_actual_arg); I'm thinking it would affect the overload priority by some trick like causing an N-deep nested conversion sequence (overload_priority<3> constructed from overload_priority<2>, from overload_priority<1>, from the integer 0) or by the constructor having N extra parameters with default arguments. Any comments or ideas for improving this?

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[parameter] accessing param type within signature
by Lorenzo Caminiti 09 May '10

09 May '10

Hello all, I am new to Boost.Parameter. I am having troubles getting the depth_first_search() example from the documentation section 2.1.5.6.2 to compile. Was the example in section 2.1.5.6.2 even compiled? If so, can someone point to the code that can be compiled? (I did look into Boost sandbox libs/parameter/... but I did not see it there.) 1) I need to access graph_type to write type requirements of following parameters. 2) The documentation section 2.1.5.6.1 says I can use graph_type (or xyz_type in general) from within the signature to refer to the parameter type. However, that seems not to be the case (also looking at the preprocessed code, xyz_type is a template parameter available only in the function body but not in the signature). 3) The documentation section 2.1.5.6.2 seems to use tag::graph::_ instead of graph_type to access the type (also sometimes graphs::graph::_ is used but I think that might be a typo... because the tag namespace should be there as in graphs::tag::graph::_). 4) Finally, even when I try to use tag::graph::_ to refer to graph_type, I get the GCC error below. What am I doing wrong? // File: g00.cpp #include <boost/parameter.hpp> namespace graphs { BOOST_PARAMETER_NAME(graph) BOOST_PARAMETER_NAME(graph2) BOOST_PARAMETER_FUNCTION( (void), depth_first_search, tag, (required (graph, *) (graph2, (tag::graph::_)) // Trying to use graph's type here... but I can't use graph_type and graph::_ does not compile... ) ) { // Here I can use graph_type. } } // namespace int main() { graphs::depth_first_search(1, 2); return 0; } $ g++ -Wall -Werror -I./src -DCONTRACT_CHECK_BLOCK_INVARIANT -DCONTRACT_CHECK_CLASS_INVARIANT -DCONTRACT_CHECK_PRECONDITION -DCONTRACT_CHECK_POSTCONDITION example/Own/parameter/g00.cpp /usr/include/boost/parameter/value_type.hpp: In instantiation of ‘boost::parameter::value_type<mpl_::arg<2>, graphs::tag::graph, boost::parameter::void_>’: example/Own/parameter/g00.cpp:9: instantiated from ‘typename graphs::boost_param_result_17depth_first_search<Args>::type graphs::boost_param_impldepth_first_search(const Args&) [with Args = boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<graphs::tag::graph2, const int>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<graphs::tag::graph, const int>, boost::parameter::aux::empty_arg_list> >]’ example/Own/parameter/g00.cpp:9: instantiated from ‘typename graphs::boost_param_result_17depth_first_search<typename boost::parameter::aux::argument_pack<graphs::boost_param_params_17depth_first_search<int>, const ParameterArgumentType0, const ParameterArgumentType1, boost::parameter::void_, boost::parameter::void_, boost::parameter::void_>::type>::type graphs::depth_first_search(const ParameterArgumentType0&, const ParameterArgumentType1&, typename boost::parameter::aux::match<graphs::boost_param_params_17depth_first_search<int>, ParameterArgumentType0, ParameterArgumentType1, boost::parameter::void_, boost::parameter::void_, boost::parameter::void_>::type) [with ParameterArgumentType0 = int, ParameterArgumentType1 = int]’ example/Own/parameter/g00.cpp:24: instantiated from here /usr/include/boost/parameter/value_type.hpp:60: error: no type named ‘binding’ in ‘struct mpl_::arg<2>’ /usr/include/boost/parameter/value_type.hpp:62: error: no type named ‘binding’ in ‘struct mpl_::arg<2>’ example/Own/parameter/g00.cpp: In function ‘typename graphs::boost_param_result_17depth_first_search<Args>::type graphs::boost_param_impldepth_first_search(const Args&) [with Args = boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<graphs::tag::graph2, const int>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<graphs::tag::graph, const int>, boost::parameter::aux::empty_arg_list> >]’: example/Own/parameter/g00.cpp:9: instantiated from ‘typename graphs::boost_param_result_17depth_first_search<typename boost::parameter::aux::argument_pack<graphs::boost_param_params_17depth_first_search<int>, const ParameterArgumentType0, const ParameterArgumentType1, boost::parameter::void_, boost::parameter::void_, boost::parameter::void_>::type>::type graphs::depth_first_search(const ParameterArgumentType0&, const ParameterArgumentType1&, typename boost::parameter::aux::match<graphs::boost_param_params_17depth_first_search<int>, ParameterArgumentType0, ParameterArgumentType1, boost::parameter::void_, boost::parameter::void_, boost::parameter::void_>::type) [with ParameterArgumentType0 = int, ParameterArgumentType1 = int]’ example/Own/parameter/g00.cpp:24: instantiated from here example/Own/parameter/g00.cpp:9: error: no matching function for call to ‘boost::parameter::aux::cast<void ()(boost::parameter::value_type<mpl_::arg<2>, graphs::tag::graph, boost::parameter::void_>)>::execute(const int&)’ /usr/include/boost/parameter/aux_/cast.hpp:99: note: candidates are: static boost::parameter::aux::use_default_tag boost::parameter::aux::cast<void ()(T)>::execute(boost::parameter::aux::use_default_tag) [with T = boost::parameter::value_type<mpl_::arg<2>, graphs::tag::graph, boost::parameter::void_>] /usr/include/boost/parameter/aux_/cast.hpp:109: note: static T boost::parameter::aux::cast<void ()(T)>::execute(T) [with T = boost::parameter::value_type<mpl_::arg<2>, graphs::tag::graph, boost::parameter::void_>] example/Own/parameter/g00.cpp:9: error: return-statement with a value, in function returning 'void' $ g++ --version g++ (GCC) 4.2.4 (Ubuntu 4.2.4-1ubuntu4) Copyright (C) 2007 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. I have tried this on Boost 1.42.0 and 1.34.1 (same errors). Thank you very much. -- Lorenzo

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