April 2016 - Boost - lists.preview.boost.org

[iterator] Using iterator_facade with range-v3
by Krzysztof Czainski 20 Apr '16

20 Apr '16

I'm having trouble using iterators implemented in terms of boost::iterator_facade with the range-v3 library. The problem is decltype(it++) which in my case is postfix_increment_proxy<>, desn't model the Readable concept, because it isn't DefaultConstructible and doesn't have a ppublic value_type nested typedef. To me it seems reasonable to require decltype(it++) to model Readable, so I created a ticket (a test case and a patch with the proposed solution included) please see: https://svn.boost.org/trac/boost/ticket/12071 See also the discussion at range-v3: https://github.com/ericniebler/range-v3/issues/304 Kind regards, Kris

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Need to use SHA1 implementation in boost
by Vinnie Falco 19 Apr '16

19 Apr '16

Greetings everyone, I'm new to the boost development mailing list. I'm preparing a library for boost review, and it needs a SHA1 implementation. I have my own header only version I took from the net, based on https://github.com/vog/sha1. I see that there's already a SHA1 implementation already in the boost, its part of UUID: https://github.com/boostorg/uuid/blob/develop/include/boost/uuid/sha1.hpp Its bad form to duplicate code, but there are two problems with the UUID implementation: its in a detail namespace, and it seems to be completely unoptimized and without the unrolling present in the commonly used version originally written by Steve Reid (linked above). What should I do? I'm guessing, some combination of the following: 1. Use UUID SHA1 as-is, even though its in a detail namespace. 2. Submit a pull request to UUID to make the SHA1 class a public interface. The problem here is the bar for public interfaces is quite high. I envision endless bike shedding (is "processs_bytes" the right name?) 3. Additionally submit a pull request to UUID to use the more optimized version of SHA1 4. Use my own version in my library submission, make it a detail class. Thanks

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Fw: new important message
by Birgit Moeller 19 Apr '16

19 Apr '16

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[thread] scoped_thread' move assignment
by Andrzej Krzemienski 18 Apr '16

18 Apr '16

Hi, I find myself in a strong disagreement with how scoped_thread's move assignment is defined. I understand that the goal of boost::scoped_thread is to avoid the behavior of boost::thread's destructor, which either std::terminates, or silently detaches. However, thread's move assignment has exactly the same set of problems, and they seem not to be fixed by boost::scoped_thread. Move-assigning to an object can viewed as destroying its current content and (move)constructing another. I would intuitively expect the same CallableThread()(t_)to be called. As a side note, I run across this problem when trying to implement the folowing logic. I have a running thread. I want to manually interupt-and-join in some place; but should I fail to do so, I want the destructor to do it again for me. I found that impossible to express with boost::scoped_thread. (Did I miss smething?). I expected that the move assignment would do the trick, but, lo, it does not. Regards, &rzej

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thread interruption request
by Gaetano Mendola 17 Apr '16

17 Apr '16

Is there a way for an interruption point to not reset the interruption request flag before throwing? I have a Class accepting functions to be executed asynchronously this is implemented in terms of boost threads: T::operator()() { while (true) { foo(); boost::this_thread::interruption_point(); } } One of those functions performs some operations between a: try { /*code*/ } catch(...) { } this basically makes my Class not interruptible indeed that boost::this_thread::interruption_point() is useless if a boost::thread_interrupted has been catched inside the foo. I have found this: http://lists.boost.org/boost-users/2008/08/39106.php where the guys needs a way to reset it, I need a way to leave the flag on for the entire thread life if an interruption has been requested. Regards Gaetano Mendola --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

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[CMake] what to do now?
by boost＠glenstark.net 16 Apr '16

16 Apr '16

Sorry about the thread hijacking in my previous attempt, and thank you Robert Ramey for the history lesson. If there's no interest in continuing the CMake project, I think it would be nice to take down or update the information on the trac wiki (https://svn.boost.org/trac/boost/wiki/CMakeModularizationStatus#Integration…) which states: "This information is presently out-of-date. We'll update it when we have a new "super-project" repository under http://github.com/boostorg/." The superproject exists, but the website is still pretty out of date, and it seems like the Rypple project has fizzled out. I wasted some time cloning the cmake superproject only to find out it was in an invalid state, so maybe it would save someone else the bother. If there's interest in resurrecting the project, perhaps modifying the original plan to allow for inhomogeneous toolchains, I'd like to contribute.

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[Root Pointer] New Documentation
by Phil Bouchard 15 Apr '16

15 Apr '16

Greetings, - I beefed up the tutorial in the following documentation and now it covers everything I know about it: http://philippeb8.github.io/root_ptr/ - As some of you already know I added a performance comparison chart in the introduction: http://philippeb8.github.io/root_ptr/root_ptr/intro.html - I fixed the deadlinks - I added a cast operation helper in the root_ptr class: https://github.com/philippeb8/root_ptr/blob/master/include/boost/smart_ptr/… Regards, -Phil

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[variant] address of a variant type from the address of its sub-object?
by Andrzej Krzemienski 15 Apr '16

15 Apr '16

Hi, Is there a portable way (guaranteed by the interface) to do the following? I have an object 'ob' of type Ob and know its address. I know it is an active sub-object of a variant type, where Ob is one of the sub-types. Is there a way to compute the address of the containing variant object? The problem I am solving is to how to access the whole variant object from inside a static visitor: ``` using VariantOb = boost::variant<Ob>; struct MyVisitor : boost::static_visitor<> { void operator()(Ob const& ob) const { // --> get the address of the variant object ? boost::addressof(ob) + what_offset; ?? } }; ``` Regards, &rzej

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Invoking a library's build//stage ignores --stagedir?
by Peter Dimov 14 Apr '16

14 Apr '16

Let's suppose that for some random reason I want to stage Boost.System into c:\stage with the current directory being outside the Boost root, which is at c:\projects\boost-git\boost: C:\Users\Peter Dimov>b2 -sBOOST_ROOT=c:\projects\boost-git\boost --stagedir=c:\stage c:/projects/boost-git/boost/libs/system/build//stage This doesn't work. Or rather, it works, but stages into C:\projects\boost-git\boost\libs\system\stage, ignoring the --stagedir. I have no idea why. I tried to debug with -d+7, and BOOST_STAGE_LOCATE is set correctly from --stagedir, but then Boost.System is staged to its local stage directory. Does anyone have an idea what's wrong here?

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[multiprecision] Bug in double to cpp_bin_float conversion?
by Rob Conde 14 Apr '16

14 Apr '16

Consider the following code: #include <boost/multiprecision/cpp_bin_float.hpp> #include <iostream> int main() { typedef boost::multiprecision::cpp_bin_float_quad float128_t; float128_t f1(1e-9); float128_t f2("1e-9"); std::cout << std::setprecision(std::numeric_limits<float128_t>::max_digits10); std::cout << f1 << std::endl; std::cout << f2 << std::endl; return 0; } I'm getting as output: 1.000000000000000062281591457779856419e-09 9.999999999999999999999999999999999325e-10 The conversion of the double literal is not as expected. On wand box: http://melpon.org/wandbox/permlink/uSGNQZAEEytmb3ao Is this a bug? If not, what would be the correct way to get my expected behavior? Thanks, Rob Conde

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