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[regression] results pages not updating
by Joaquin M López Muñoz 04 Jan '18

04 Jan '18

Hi, Just a heads up, regression tests result pages: http://www.boost.org/development/tests/master/developer/summary.html http://www.boost.org/development/tests/develop/developer/summary.html aren't updating since Jan 1. Thank you, Joaquín M López Muñoz

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Interest for a Fixed Point Arithmetics library
by Julien Vernay 03 Jan '18

03 Jan '18

Hello everybody. I am working on a project that needs and can use fixed point numbers, so I started searching for a library implementing fixed point numbers, but I didn't find anything. So I was wondering if people would need fixed point arithmetics, and here I am. The aim of this FixedPointNumber is to fix the point at compile-time using template, and having another template argument for the underlying type. So we have : template<typename T, size_t N> class FixedPointNumber { T value; public: //interface }; The N last bits of value is the decimal part : so to convert a FixedPointNumber to an int, we need only to use a bitshift operator (and same for construction from int). sizeof(FixedPointNumber<T,N>) == sizeof(T) , so there is no overhead in this implementation. Arithmetic and relational operators will be implemented. Multiplication needs one int multiplication and one bit shift. Division needs one int division and one bit shift. There is only one value for zero. Sign can be extracted with Most Significant Bit. I have already a basic implementation but if it interests more people I will do a proper implementation. Thank you for reading !

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[multiprecision] Help needed with strange constexpr slowdown
by John Maddock 03 Jan '18

03 Jan '18

Folks I have a very strange issue that I need help with understanding, it comes from https://github.com/boostorg/multiprecision/issues/32 but in summary: Given: #include <iostream> #include <boost/multiprecision/cpp_int.hpp> using namespace std; using namespace boost::multiprecision; int main() { __int128_t i =0; __int128_t j =0; int256_t sum =0; for (; i <1e9; i +=19, j +=13) { int256_t diff = j; sum += i * diff; } std::cout <<"Result: " << sum << std::endl; return 0; } There is a 20-30% slowdown when compiled in C++11 or later compared to C++03 with gcc 5.x or 6.x. I've tracked this down to the constexpr default constructor for int256_t (which is called inside operator* to create a temporary for the result), if I make the default constructor non-constexpr by removing BOOST_CONSTEXPR from any of: number.hpp:44 (number()) cpp_int.hpp:1077 (cpp_int_backend()) cpp_int.hpp:501 (cpp_int_base()) cpp_int.hpp: 435 (cpp_int_base::data_type()) Then the slowdown disappears. All the line numbers refer to current develop BTW. gcc-7 is better, but I notice it still generates different code if the constructor is constexpr - that greatly surprises me to be frank - is there something I'm missing about constexpr-ness that could cause this? Confused yours, John. --- This email has been checked for viruses by AVG. http://www.avg.com

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Need help with bootstrap.bat
by Andrzej Krzemienski 03 Jan '18

03 Jan '18

Hi Everyone, Maybe someone can help me with configuring bootstrap.bat. I am trying to set up the environment for developing boost libraries, and it is my understanding that the first step (after cloning a git repository) is to build b2 itself using the script bootstrap.bat. I got this from instructions at https://github.com/boostorg/boost/wiki/Getting-Started (n.b. It was very difficult to find this page as there is no direct link from www.boost.org) I am using MinGW on Windows, no Visual Studio installed. Nonetheless bootstrap.bat concludes that it should compile with cl.exe, and it does not work. I know that MinGWis not supported, but I have to take my chances. Maybe somebody knows how to instruct bootstrap.bat to select a GCC compiler and tools? Regards, &rzej;

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help for contribution
by ashwin.pathak 03 Jan '18

03 Jan '18

Hi Developers, I am very interested in computer programming and I find boost c++ libraries really exciting. I would like to contribute to the organization, I am new to this organization. Can someone please help me to get started in contributing to the organization. Thank you, Best Regards, Ashwin Pathak

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Re: [boost] Boost.HTTPKit, a new library from the makers of Beast!
by Vinnie Falco 01 Jan '18

01 Jan '18

On Sun, Oct 8, 2017 at 5:38 PM, Vinícius dos Santos Oliveira <vini.ipsmaker(a)gmail.com> wrote: > Now, moving on... given that you have __not__ answered how your parser's > design[1] compares to the parser I've developed I'll try to provide more clarity. `beast::basic_parser` is designed with standardization in mind, as I intent to eventually propose Beast for the standard library. Therefore, I have made the interface as simple as possible, exposing only the minimum required necessary to achieve these goals which the majority of users want: * Read the header first, if desired * Feed Asio style buffer sequences into the parser * Set independent limits on the number of header and body octets * Optional fine-grained receipt of chunked body data and metadata The design of basic_parser (the use of CRTP in particular) is meant to support the case where a user implements their own Fields container, or if they want a bit more custom handling of the fields (for example, to avoid storing them). Like all design choices, tradeoffs are made. The details of parsing are exposed only to the derived class. Complexities are hidden from the public-facing interface of `basic_parser`. Implementing a stream algorithm that operates on the parser is a straightforward process: template< class SyncReadStream, class DynamicBuffer, bool isRequest, class Derived> std::size_t read(SyncReadStream& stream, DynamicBuffer& buffer, basic_parser<isRequest, Derived>& parser, error_code& ec) { parser.eager(true); if(parser.is_done()) { ec.assign(0, ec.category()); return 0; } std::size_t bytes_transferred = 0; do { bytes_transferred += read_some( stream, buffer, parser, ec); if(ec) return bytes_transferred; } while(! parser.is_done()); return bytes_transferred; } > [1] at most it hides behind a “multiple people/stakeholders agree with me” > __shield__ There's no hiding going on here. One can only measure the relative success of designs based on the feedback from users. They opened issues, and I addressed their use-cases, sometimes with a considerable amount of iteration and back-and-forth as you have seen in the GitHub issues quoted in the previous message. Now, I don't know if the sampling of users that have participated in Beast's design are representative of the entire C++ community. However, I do know one thing - if GitHub stars are any measure of the sample size of the participants, then Beast is off to a good start. Here's a graph showing the number stars over time received by boostorg/beast, tufao, and Boost.Http (the last 2 libraries having you as the author I believe): <http://www.timqian.com/star-history/#boostorg/beast&BoostGSoC14/boost.http&…> (Note that the HTTP+WebSocket version of Beast was released in May 2016). We need to be careful interpreting results like this of course so perhaps we should look at different metrics. Here are the links to the number of closed issues for Beast, tufao, and Boost.Http: 502 Closed issues in Beast: <https://github.com/boostorg/beast/issues?q=is%3Aissue+is%3Aclosed> 38 Closed issues in tufao <https://github.com/vinipsmaker/tufao/issues?q=is%3Aissue+is%3Aclosed> 13 Closed issues in Boost.HTTP, from 6 unique users not including the author <https://github.com/BoostGSoC14/boost.http/issues?q=is%3Aissue+is%3Aclosed> Again we have to be careful interpreting results like this. But it sure looks like there is a lot of user participation in Beast. If approval from a large number of stakeholders is not a compelling design motivator then what is? > This tutorial is full of “design implications” blocks where I take the time > to dissect what it means to go with each choice. Thus far, no one has asked for more fine grained access to incoming HTTP tokens in the manner of `code::method` and `code::request_target`. If this becomes something that users consistently ask for, it can be done by changing the requirements for the derived class for `basic_parser`. This way, details about HTTP parsing which most people don't care about will not leak into the beast::http:: namespace. Such a change would not affect existing stream algorithms on parsers. Thanks

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Re: [boost] What hash functions should be included in a hypothetical Boost hash-v2 library?
by Bjorn Reese 31 Dec '17

31 Dec '17

On 12/31/17 01:28, Peter Dimov via Boost wrote: > What (non-cryptographic) hash functions should a hypothetical future > Boost hash library contain? Have clear winners emerged by now? Which > ones do people prefer? I vote for FNV hashes: https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function

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What hash functions should be included in a hypothetical Boost hash-v2 library?
by Peter Dimov 31 Dec '17

31 Dec '17

What (non-cryptographic) hash functions should a hypothetical future Boost hash library contain? Have clear winners emerged by now? Which ones do people prefer? SipHash is basically a given, but it's not optimized for speed.

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Removing hash from Boost.Functional broke modules
by James E. King, III 28 Dec '17

28 Dec '17

See: https://github.com/boostorg/type_index/issues/18 There is no forwarding header to keep things compatible. - Jim

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Maintenance of Boost.DateTime
by James E. King, III 28 Dec '17

28 Dec '17

The backlog for Boost.DateTime in trac has over 130 issues; the project is holding on to very old backwards compatibility code (pre-boost-1.33.0 i/o facets), and the CI builds do not currently have appveyor, codecov.io, or coverity scan integration. It needs a proper maintainer in order to resolve these issues, so I would like to ask for that privilege. Thanks, Jim

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