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[coroutine] final version?
by Oliver Kowalke 17 Oct '12

17 Oct '12

a final (?) version of boost.coroutine is available at http://ok73.ok.funpic.de/boost-coroutine.zip In contrast to the original concept coroutine<> is not similar to a function/functor. 1.) the coroutine-fn is started at construction of coroutine<> - helps to solve some problems related to the last 'yield'-operation - similar to the behaviour of boost::thread - arguments which have to be the first arguments of coroutine-fn must be applied to coroutine<>-ctor (arguments()) 2.) coroutine<>::operator() returns a reference to the coroutine instead the return-value 3.) return-values must be accessed via coroutine<>::get() regards, Oliver

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[smart_ptr] [shared_ptr] BOOST_NOEXCEPT patch
by Antony Polukhin 17 Oct '12

17 Oct '12

Hi, There is a trivial patch in ticket #7523 that marks some functions of Boost.SmartPtr library as noexcept. I'll test the patch for some more time and if there will be no objections, I'll commit it to trunk after boost_1_52_0 release. Any suggestions and comments are welcomed. -- Best regards, Antony Polukhin

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[lexical_cast] cast of int8_t
by Jochen Wilhelmy 16 Oct '12

16 Oct '12

Hi! In a previous message I asked if lexical_cast could throw boost::numeric::positive_overflow when the parsing is ok but the value too large for the target type. this turned out to be difficult because it breaks existing code, alternatively there could be another exception derived from bad_lexical_cast that indicates the overflow but this seems to be a lot of work. another question is why does lexical_cast treat int8_t and uint8_t like char? technically I see no reason for this as c++ has three types: char, signed char and unsigned char. in my code I use only char for characters and signed/unsigned char as numbers. I know that the standard stream operator << treats signed/unsigned char as char but I know no explanation for this (I consider it a bug ;-) -Jochen

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[type_erasure] any and shared_ptr
by Christophe Henry 16 Oct '12

16 Oct '12

Hi Steven, I need to use the associated types but don't get them to do what I need. Consider struct Pointee : public boost::enable_shared_from_this<Pointee> { void foo() { std::cout << "Pointee::foo called" << std::endl; //shared_from_this(); std::cout << "Pointee::foo end" << std::endl; } }; Pointee needs to be enable_shared_from_this for some reason, which forces me to use it in a shared_ptr. I reused your pointee / pointer structures: template<class T> struct pointee { typedef typename mpl::eval_if< boost::type_erasure::is_placeholder<T>, mpl::identity<void>, boost::pointee<T> >::type type; }; template<class T = _self> struct pointer : mpl::vector< copy_constructible<T>, dereferenceable<deduced<pointee<T> >&, T> > { typedef deduced<pointee<T> > element_type; }; I (naively) tried to define a pointee concept: typedef mpl::vector< pointer<>, same_type<pointer<>::element_type,_a >, relaxed_match, has_foo<void()> > PointeeConcept; // will not compile, shared_ptr<Pointee> has no foo... boost::shared_ptr<Pointee> p (new Pointee) ; any<PointeeConcept> ap (p); ap.foo(); So in the end I had to resort to a wrapper: struct PointeeWrap { PointeeWrap(boost::shared_ptr<Pointee>p):myPointee(p){} void foo() { std::cout << "PointeeWrap::foo called" << std::endl; myPointee->foo(); } boost::shared_ptr<Pointee> myPointee; }; BOOST_TYPE_ERASURE_MEMBER((has_foo), foo, 0); typedef any< mpl::vector< relaxed_match, copy_constructible<>, has_foo<void()> > > AnyPointee; boost::shared_ptr<Pointee> p (new Pointee); PointeeWrap wrap(p); AnyPointee ap(wrap); ap.foo(); But this will become tedious with an increasing number of members. Is there a better way? Thanks, Christophe

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[mpl] Nested BOOST_MPL_ASSERT fails on VC11
by Steven Watanabe 15 Oct '12

15 Oct '12

AMDG I just ran into the following bug: template<class T> struct test : T { BOOST_MPL_ASSERT((T)); }; BOOST_MPL_ASSERT((test<T>)); I've reworked BOOST_MPL_ASSERT to avoid the problem in the attached patch. Okay to commit? In Christ, Steven Watanabe

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[GIL] default_color_converter from float to integer should clamp
by Fabien Castan 15 Oct '12

15 Oct '12

Hi, The conversion from floating point image to 8 bits or 16 bits image should clamp instead of writing arbitrary values... // a floating point image, with some pixel values < 0.0 and > 1.0 boost::gil::rgba32f_view_t HDR; // use default_color_converter to convert this HDR image to 8 bits boost::gil::png_write_view( "LDR.png", boost::gil::color_converted_view<boost::gil::rgba8_pixel_t>( HDR ) ); The 8 bits LDR image contains arbitrary cast conversion values, that are not very nice. The conversion from floating point to integer values has no other valid solution than clamping. So I suggest this patch, for the file "boost/gil/channel_algorithm.hpp": @@ -272,7 +272,13 @@ template <typename DstChannelV> struct channel_converter_unsigned<bits32f,DstChannelV> : public std::unary_function<bits32f,DstChannelV> { DstChannelV operator()(bits32f x) const { typedef typename detail::unsigned_integral_max_value< DstChannelV >::value_type dst_integer_t; - return DstChannelV( static_cast< dst_integer_t >(x*channel_traits<DstChannelV>::max_value()+0.5f )); + + const bits32f convertedValue = x * channel_traits<DstChannelV>::max_value() + 0.5f; + const bits32f clampedValue = std::min( + (bits32f)channel_traits<DstChannelV>::max_value(), + std::max( (bits32f)channel_traits<DstChannelV>::min_value(), convertedValue ) ); + + return DstChannelV( static_cast< dst_integer_t >(clampedValue) ); } }; Regards, Fabien Castan

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[asio::ssl] TLS support
by ToBeKi＠gmx.de 15 Oct '12

15 Oct '12

Hello all, in asio::ssl context/context_base i couldn't find any TLS 1.1/1.2 method implementations. Is it missing/not supported yet? If so is there a roadmap supporting versions 1.1/1.2? Best, kito

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[config] call to destructor of temporary
by Vicente J. Botet Escriba 15 Oct '12

15 Oct '12

Hi, I have had some trouble debugging some code with clang-2.9 c++0x. The reason was a known bug on the compiler as it doesn't call the destructor of temporaries at the end of the expression. Is there a macro stating this missing feature? Best, Vicente

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maybe a bug in boost.iostreams
by leiming2006 15 Oct '12

15 Oct '12

Hello, I'm using boost 1.5.1 in windows 7 with vc 2010 express. today I'm trying using boost.iostreams with audio samples, whose char_type is not char or wchar_t. thought I failed at the end, but I guess that I found a bug in the library. In the file boost\iostreams\chain.hpp, line 136, I wonder if it's typedef linked_streambuf<Ch, Tr> streambuf_type; not typedef linked_streambuf<Ch> streambuf_type; Regards, LeiMing

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[program options] Support for storage to 'optional' objects
by Chris Glover 15 Oct '12

15 Oct '12

Hi, Recently when using the Boost Program options library, I was surprised to find that I was unable to pass a boost.optional object to store supplied options in. For example; namespace bpo = boost::program_options; boost::optional<std::string> opt_str; bpo::options_description desc("Allowed options"); desc.add_options() ("help", "produce help message") ("opt", bpo::value(&opt_str), "Something optional") // Store value of 'opt' in 'opt_str' ; What I expected to happen would be that 'opt_str' would be valid if 'opt' is supplied by the user, and not valid otherwise. However, the above code causes a compile error deep within lexical_cast because, of course, performing such an operation on a boost.optional doesn't make sense. The attached patch to Program Options rectifies the issue by filtering out optional objects within before calling lexical_cast, but to be honest, I'm not sure if this is the correct approach or if this is even a desirable feature. I like the idea of setting an optional object this way instead of testing the variables_map later on, but perhaps there's something I am missing or a better way to accomplish the same thing. Please have a look and let me know your thoughts. Thanks, -- chris

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