November 2012 - Boost - lists.preview.boost.org

Boost.Process 0.5: Another update/potential candidate for an official library
by Boris Schaeling 17 Nov '12

17 Nov '12

I've uploaded a new version of Boost.Process 0.5 to <http://www.highscore.de/boost/process0.5/>: - Made child movable and non-copyable on Windows (destructor closes handles) - Added cross-platform helpers in a new header file boost/process/mitigate.hpp - Updated and improved documentation (eg. FAQ is new) - Added the POSIX initializer notify_io_service (Boost.Asio helper) - Minor bug fixes and improvements (eg. in search_path() on Windows) At this point there is nothing left on my todo list. I got quite a lot of feedback so far and would appreciate if people can look at this new version again. If there are no major shortcomings found, I'll ask for a formal review. Boris

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[container] container_detail::pair piecewise constructor
by László Szécsi 17 Nov '12

17 Nov '12

Hi everyone, boost::container::container_detail::pair's piecewise constructor is missing, as acknowledged in a comment. This makes container::flat_map::emplace less useful (perhaps useless) as the following will not work: boost::container::flat_multimap<TestKey, TestValue> testMap; testMap.emplace(boost::container::container_detail::piecewise_construct, boost::make_tuple(30), boost::make_tuple(50)); where both TestKey and TestValue are non-copyable, moveable classes with a constructor taking an int. The compilation error message will correctly say that boost::container::container_detail::pair does not have a constructor with three arguments. I tried to implement the missing piecewise constructor based on std::pair's in the g++ standard libraries. I failed at it, so I would like to request some assistance and education. This is where I got: // from the standard lib template<std::size_t _Num> struct _Build_index_tuple { typedef typename _Build_index_tuple<_Num-1>::__type::__next __type; }; // from the standard lib template<> struct _Build_index_tuple<0> { typedef _Index_tuple<> __type; }; template <class... Args1, class... Args2> pair(piecewise_construct_t, ::boost::tuple<Args1...> first_args, ::boost::tuple<Args2...> second_args) : pair(::boost::move(first_args), ::boost::move(second_args), typename _Build_index_tuple<sizeof...(Args1)>::__type(), typename _Build_index_tuple<sizeof...(Args2)>::__type()) {} template<typename... Args1, std::size_t... Indices1, typename... Args2, std::size_t... Indices2> explicit pair(tuple<Args1...> tuple1, tuple<Args2...> tuple2, _Index_tuple<Indices1...>, _Index_tuple<Indices2...>) : first(::boost::forward<Args1>(std::get<Indices1>(tuple1))...), second(::boost::forward<Args2>(std::get<Indices2>(tuple2))...) { } This gets me a recursive error message far too long to quote, starting with: error C2664: 'boost::container::container_detail::pair<Key,T>::pair(std::pair<Key,T> &&)' : cannot convert parameter 3 from 'boost::tuples::tuple<int,boost::tuples::null_type // lot of null_types omitted to 'boost::tuples::tuple<boost::tuples::null_type, // lot of null_types omitted I used the VS2012 Nov CTP compiler. I understand that variadic templates have not been very portable and boost::unordered, which has a piecewise constructor implementation, does it completely differently and much more painfully. But is there a reason for the approach I tried not to work with boost at all? Could you please help me fix this code? Thank you very much, Laszlo Szecsi

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Updated serialization performance tests
by Brian Wood 16 Nov '12

16 Nov '12

Shalom I've updated this page -- http://webEbenezer.net/comparison.html with results from Boost 1.52. A few notes about the testing: I decided to use -O2 on the Linux/g++ tests. In previous tests I used -O3. I hadn't updated the Windows test results since the Boost 1.48 time-frame. Around Boost 1.51 I had to start building the serialization library in Boost with runtime-link=static in order to get the Windows tests to build. I haven't understood why that became necessary, but the results for the serialization library in Boost seem to have been adversely affected by this. On Windows, I now report that tests built with the serialization library in Boost are over 1.8 times slower than parallel Ebenezer tests. Previously I reported the tests built with the serialization library in Boost were between 1.7 and 1.8 times slower than the Ebenezer tests. -- Brian Ebenezer Enterprises -- making programming fun again. http://webEbenezer.net

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Boost.Test and Xcode 4.5 in C++11 Mode
by Dean Michael Berris 16 Nov '12

16 Nov '12

Hi Everyone, I'm trying to build Boost.Test in trunk in C++11 mode with Apple's released Clang compiler with Xcode 4.5. Is this supported by Boost.Test? I keep getting this error somewhere deep in some preprocessor parts which is far outside my understanding. Here's my user-config.jam: using clang : : : <cxxflags>-Wall <cxxflags>-Wself-assign <cxxflags>-std=c++11 <cxxflags>-stdlib=libc++ <linkflags>-stdlib=libc++ ; I ask because I'm using Boost.Test as my current unit testing framework for cpp-netlib. I'm going to need to make a decision on whether I can continue using Boost.Test in C++11 mode as cpp-netlib is moving to C++11-only in its next version. Thanks in advance. -- Dean Michael Berris www.deanberris.com

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[test] A new ERROR in trunk including C++11 features on C++98 mode
by Vicente J. Botet Escriba 16 Nov '12

16 Nov '12

Hi, there is yet an error including C++11 features. Please could you take care of it? Thanks, Vicente darwin.compile.c++ ../../../bin.v2/libs/test/build/darwin-4.2.1/debug/link-static/threading-multi/framework.o In file included from ../../../boost/test/tools/assertion.hpp:19, from ../../../boost/test/tools/impl.hpp:25, from ../../../boost/test/test_tools.hpp:373, from ../../../boost/test/impl/framework.ipp:27, from ../../../libs/test/src/framework.cpp:16: ../../../boost/test/utils/is_forward_iterable.hpp:58: error: ‘>>’ should be ‘> >’ within a nested template argument list ../../../boost/test/utils/is_forward_iterable.hpp:61: error: ‘>>’ should be ‘> >’ within a nested template argument list "g++" -ftemplate-depth-128 -O0 -fno-inline -Wall -pedantic -g -gdwarf-2 -fexceptions -DBOOST_ALL_NO_LIB=1 -I"../../.." -c -o "../../../bin.v2/libs/test/build/darwin-4.2.1/debug/link-static/threading-multi/framework.o" "../../../libs/test/src/framework.cpp" ...failed darwin.compile.c++ ../../../bin.v2/libs/test/build/darwin-4.2.1/debug/link-static/threading-multi/framework.o...

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BOOST_FUSION_ADAPT_STRUCT - Printing Array Elements
by forums_mp 16 Nov '12

16 Nov '12

Given the snippet below. How do I print the contents within the array ? I'd expect to see a counting pattern when the array is encountered but that's not the case. Thanks in advance. [code] #include <boost/mpl/eval_if.hpp> #include <boost/mpl/identity.hpp> #include <boost/mpl/next_prior.hpp> #include <boost/fusion/mpl.hpp> #include <boost/fusion/adapted.hpp> // BOOST_FUSION_ADAPT_STRUCT // boost::fusion::result_of::value_at #include <boost/fusion/sequence/intrinsic/value_at.hpp> #include <boost/fusion/include/value_at.hpp> // boost::fusion::result_of::size #include <boost/fusion/sequence/intrinsic/size.hpp> #include <boost/fusion/include/size.hpp> // boost::fusion::at #include <boost/fusion/sequence/intrinsic/at.hpp> #include <boost/fusion/include/at.hpp> # include <iostream> # include <vector> typedef std::vector < int > INT_VEC ; // Your existing struct struct my_struct { int i; bool j; int arr1 [ 100 ]; // INT_VEC vv ; // my_struct() // : vv ( 100 ) // {} }; // Generate an adapter allowing to view "Foo" as a Boost.Fusion sequence BOOST_FUSION_ADAPT_STRUCT( my_struct, (int, i) (bool, j) (int, arr1[ 100 ] ) // (int, vv[100]) ) template <typename T2> struct parse_foo { static void parse(T2 & f); }; struct display { template <typename T> void operator()(T& t) const { std::printf(" --%s--%s-- \n", typeid(t).name(), boost::lexical_cast<std::string>(t).c_str()); if (typeid(t).name()[0] == 'c') std::printf(" --%s--%s-- \n", typeid(t).name(), t); parse_foo<T>::parse(t); } }; template <> void parse_foo<int >::parse(int & f) { std::cout << f << std::endl; } template <> void parse_foo<char>::parse(char & f) {}; template <> void parse_foo<bool>::parse(bool & f) { std::cout << f << std::endl; }; #include <boost/fusion/include/sequence.hpp> #include <boost/fusion/include/algorithm.hpp> #include <boost/fusion/include/vector.hpp> #include <boost/fusion/include/adapt_struct.hpp> #include <boost/lexical_cast.hpp> int main() { my_struct f; f.i = 33 ; f.j = false ;; for ( int odx ( 0 ); odx < 100; ++odx ) { f.arr1 [ odx ] = odx ; } boost::fusion::for_each(f, display()); } [/code] -- View this message in context: http://boost.2283326.n4.nabble.com/BOOST-FUSION-ADAPT-STRUCT-Printing-Array… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Re: [boost] [Boost-commit] svn:boost r81360 - in trunk: boost/algorithm libs/algorithm/test
by Steven Watanabe 15 Nov '12

15 Nov '12

AMDG On 11/15/2012 11:45 AM, marshall(a)idio.com wrote: > <snip> > + // construct/copy > + BOOST_CONSTEXPR basic_string_ref () > +#ifdef BOOST_NO_CXX11_NULLPTR > + : ptr_(NULL), len_(0) {} > +#else > + : ptr_(nullptr), len_(0) {} > +#endif Really? The two branches have exactly the same effect. The only reason to prefer nullptr is aesthetic and this is more than offset by the #ifdef. > + > + basic_string_ref(const charT* str) > + : ptr_(str), len_(std::strlen(str)) {} > + strlen only works for char. You need to use traits::length > +#ifndef BOOST_NO_CXX11_HDR_INITIALIZER_LIST > +// !! How do I do this? Look how initializer_lists work! > + basic_string_ref(std::initializer_list<charT> il); // TODO > +#endif > + Although this can be implemented, it's incredibly dangerous, because the string_ref will be left dangling when the initializer_list goes out of scope. > + > + // iterators > + BOOST_CONSTEXPR const_iterator begin() const { return ptr_; } > + BOOST_CONSTEXPR const_iterator cbegin() const { return ptr_; } > + BOOST_CONSTEXPR const_iterator end() const { return ptr_ + len_; } > + BOOST_CONSTEXPR const_iterator cend() const { return ptr_ + len_; } > + const_reverse_iterator rbegin() const { return const_reverse_iterator (end()); } > + const_reverse_iterator crbegin() const { return const_reverse_iterator (end()); } > + const_reverse_iterator rend() const { return const_reverse_iterator (begin()); } > + const_reverse_iterator crend() const { return const_reverse_iterator (begin()); } > + Check for tabs? > + // capacity > + BOOST_CONSTEXPR size_type max_size() const { return len_; } I'm not convinced that this definition is correct. Returns: the size of the largest possible string. Note that this does not say that it returns the maximum size that this particular string_ref object can hold without reassignment. > + > + int compare(basic_string_ref x) const { > + int cmp = std::memcmp ( ptr_, x.ptr_, std::min(len_, x.len_)); > + return cmp != 0 ? cmp : ( len_ == x.len_ ? 0 : len_ < x.len_ ? -1 : 1 ); > + } > + > + bool starts_with(charT c) const { return !empty() && front() == c; } > + bool starts_with(basic_string_ref x) const { > + return len_ >= x.len_ && std::memcmp ( ptr_, x.ptr_, x.len_ ) == 0; > + } > + > + bool ends_with(charT c) const { return !empty() && back() == c; } > + bool ends_with(basic_string_ref x) const { > + return len_ >= x.len_ && std::memcmp ( ptr_ + len_ - x.len_, x.ptr_, x.len_ ) == 0; > + } > + You can only use memcmp for char. You have to use traits::compare here. > + > +// Have to use traits here > + size_type find(basic_string_ref s) const { > + const_iterator iter = std::find_if ( this->cbegin (), this->cend (), > + s.cbegin (), s.cend (), traits::eq ); > + return iter = this->cend () ? npos : std::distance ( this->cbegin (), iter ); > + } > + I think you mean std::search, not std::find_if. > + size_type find(charT c) const { > +#ifdef BOOST_NO_CXX11_LAMBDAS > + const_iterator iter = std::find_if ( this->cbegin (), this->cend (), > + detail::string_ref_traits_eq<charT, traits> ( c )); > +#else > + const_iterator iter = std::find_if ( this->cbegin (), this->cend (), > + [c] ( charT val ) { return traits::eq ( c, val ); } ); > +#endif > + return iter == this->cend () ? npos : std::distance ( this->cbegin (), iter ); > + } > + As with NULL/nulptr, I don't see the point of using C++11 lambdas if you have to #ifdef it with a C++03 implementation. In Christ, Steven Watanabe

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[multiprecision] OK to merge to Trunk?
by John Maddock 15 Nov '12

15 Nov '12

Folks, Unless there are any objections, I'd like to merge the multiprecision library to SVN Trunk pretty soon. Here are the main changes since the review, which have mostly concentrated on the interface changes: * Non-expression template operators further optimized with rvalue reference support. * Many functions made `constexp`. * Differentiate between explicit and implicit conversions in the number constructor. * Removed "mp_" prefix from types. * Allowed mixed precision arithmetic. * Changed ExpressionTemplates parameter to class `number` to use enumerated values rather than true/false. * Changed ExpressionTemplate parameter default value to use a traits class so that the default value depends on the backend used. * Added support for fused-multiply-add/subtract with GMP support. * Tweaked expression template unpacking to use fewer temporaries when the LHS also appears in the RHS. * Refactored `cpp_int_backend` based on review comments with new template parameter structure. * Added additional template parameter to `mpfr_float_backend` to allow stack-based allocation. * Added section on mixed precision arithmetic, and added support for operations yielding a higher precision result than either of the arguments. * Added overloads of integer-specific functions for built in integer types. Things requested in review, but not yet done: * We can reuse temporaries in multiple subtrees (temporary caching). Low priority for now. * cpp_dec_float should round to nearest. Chris currently has no time for this, and it's really hard to do *right*. * A 2's complement fixed precision int that uses exactly N bits and no more. Refactoring of cpp_int should make this easier to add as an option in future. There are also documentation updates pending (mostly relating to the new improved performance results), and more tests I want to add/run, bit basically I need to get things widely tested to move forward now. Release schedule wise, I think it'll be hard to get things ready for the next release, but the release after that really should be on the cards. So basically now is the last chance for folks to complain before the interface gets ossified ;-) As ever current code is in the sandbox under /big_number/ and docs can be viewed online here: http://svn.boost.org/svn/boost/sandbox/big_number/libs/multiprecision/doc/h… Regards, John.

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boost filesystem path as utf-8 revisited
by Rush Manbert 15 Nov '12

15 Nov '12

In the original thread, I found this reply by Beman: ----------------- > > > How exactly do I imbue UTF-8 codecvt in a path? I Googled around and > couldn't find anything. There are two approaches: * If you always want all class path arguments and returned values with a value type of char to be treated as being UTF-8 encoded, and aren't worried about changing a potentially dangerous global, then do this: #include <boost/filesystem/detail/utf8_codecvt_facet.hpp> ... std::locale global_loc = std::locale(); std::locale loc(global_loc, new boost::filesystem::detail::utf8_codecvt_facet); boost::filesystem::path::imbue(loc); ----------------- I do want what is described and would like to use this approach, but we use boost::filesystem all over the place and in our code we never do any sort of "global initialization", so I'm trying to figure out how to get the code snippet executed. I can see two ways to approach this: 1) Add this code snippet to the boost::filesystem::path constructor. But is it too late then? 2) Define a class whose only purpose is to execute this code when it is constructed and arrange to have a static singleton instance of the class defined. In one of our libraries we need to be very careful about static class construction order, so this may be difficult. I haven't dealt with this sort of issue in quite a while and I may be a little rusty. Any suggestions? Are there new goodies in C++ that might help me? Thanks, Rush

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program_options::store() interface extension
by ST 15 Nov '12

15 Nov '12

Hi, I need to supply to my app a config file with following entries: item1 = 123 item2 = 435 item3 = 345 ... itemN = 562 where N is not known in advance, so there is no way to register such options. The only way to deal with them is to pass them as unregistered options and then use collect_unrecognized(). But then dealing with a vector<string> is not quit convenient. My suggestion is to add an a storeUnregistered flag to the store() function which will be false by default, but if set to true, will store all unregistered options with their values as strings. It will be possible then to check whether an item was provided like this: vm.count("item1") and cast its value like this: vm["item1"].as<int>() . Or is there already a good way to do what I need? Thank you in advance, ST

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